Halley's Comet: Wikis

  
  
  
  

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1P/Halley (Halley's Comet)
A color image of Comet Halley, shown flying to the left aligned flat against the sky
Discovery
Discovered by prehistoric (observation);
Edmond Halley (recognition of periodicity)
Epoch 2449400.5
(17 February 1994)
Aphelion 35.1 AU
(9 December 2023)[2]
Perihelion 0.586 AU
last perihelion: 9 February 1986
next perihelion: 28 July 2061[2]
Semi-major axis 17.8 AU
Eccentricity 0.967
Orbital period 75.3 a[1]
Inclination 162.3°
Physical characteristics
Dimensions 15×8 km,[3] 11 km (mean)[1]
Mass 2.2 × 1014 kg[4]
Mean density 0.6[5] (estimates range from 0.2 to 1.5 g/cm3[6])
Sidereal rotation
period
2.2 d (52.8 h) (?)[7]
Albedo 0.04[8]
Apparent magnitude 28.2 (in 2003)[9]
.Halley's Comet or Comet Halley (officially designated 1P/Halley)[1] is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years.^ Halley's Comet or Comet Halley (officially designated 1P/Halley) is the most famous of the periodic comets, and is visible every 75 to 76 years.
  • Comet K-12 Experiments and Background Information 10 February 2010 13:37 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]

^ Comet d’Arrest is in a short-period orbit with a period of 6.5 years.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ Halley’s Comet , also known as Comet Halley, is the most well known periodic comet.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[1][10] .Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime.^ Halley's Comet appeared in the late Fall.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ This was a naked-eye comet for the Southern Hemisphere.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[11] .Other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years.^ So, it appear that the hangar may have been only grazed.
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ This was a naked-eye comet for the Southern Hemisphere.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Besides its visibility and relatively short orbital period, Halley's comet has been observed by -- and has influenced -- human societies for more than 2,000 years.
  • Nothing but the facts about Halley's Comet 10 February 2010 13:37 UTC www.brighthub.com [Source type: General]

.Halley's returns to the inner Solar System have been observed by astronomers since at least 240 BC, and recorded by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object.^ List of solar system objects .
  • Comet - Discussion and Encyclopedia Article. Who is Comet? What is Comet? Where is Comet? Definition of Comet. Meaning of Comet. 10 February 2010 13:37 UTC www.knowledgerush.com [Source type: FILTERED WITH BAYES]

^ An extended tour of the inner Solar System.

^ The oldest written source that can be granted to the apparition of Halley's Comet is from 240 BC and was recorded by Chinese astronomers.
  • Newgrange may be a metaphor for Halley's Comet 10 February 2010 13:37 UTC www.newgrange.com [Source type: FILTERED WITH BAYES]

.The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named.^ P/Halley is named for Edmund Halley, the first person to recognise the periodicity of this comet.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ This comet is now known as Halley's Comet.

^ AD :- Halley Comet return for the first time a predicted by Edmond Halley.

Halley's Comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061.[12]
.During its 1986 apparition, Halley's Comet became the first to be observed in detail by spacecraft, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail formation.^ Is Newgrange related to apparitions of Halley's Comet?
  • Newgrange may be a metaphor for Halley's Comet 10 February 2010 13:37 UTC www.newgrange.com [Source type: FILTERED WITH BAYES]

^ What scientific observations were employed during Comet Halley's last return?
  • Halleys comet Facts, information, pictures | Encyclopedia.com articles about Halleys comet 10 February 2010 13:37 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

[13][14] .These observations supported a number of longstanding hypotheses about comet construction, particularly Fred Whipple's "dirty snowball" model, which correctly surmised that Halley would be composed of a mixture of volatile ices—such as water, carbon dioxide and ammonia—and dust.^ They are composed of rock, dust, ice and frozen gases such as carbon monoxide, carbon dioxide, methane, and ammonia.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ They are composed of rock, dust, ice, and frozen gases such as carbon monoxide, carbon dioxide, methane, and ammonia.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comets are composed of significant fractions of water ice, dust, and carbon-based compounds.
  • Comet Facts - Explore the Cosmos | The Planetary Society 10 February 2010 13:37 UTC planetary.org [Source type: FILTERED WITH BAYES]

.However, the missions also provided data which substantially reformed and reconfigured these ideas; for instance it is now understood that Halley's surface is largely composed of dusty, non-volatile materials, and that only a small portion of it is icy.^ He created a theory about the brightness of the comets coming from the evaporation from a solid object and that the non-gravitational forces of comet Encke were caused by the jet forces created as the material evaporated from the surface of the object.
  • Comet - Discussion and Encyclopedia Article. Who is Comet? What is Comet? Where is Comet? Definition of Comet. Meaning of Comet. 10 February 2010 13:37 UTC www.knowledgerush.com [Source type: FILTERED WITH BAYES]

^ A 'comet ' is a relatively small object similar to an asteroid but composed largely of ice.
  • Comet - Discussion and Encyclopedia Article. Who is Comet? What is Comet? Where is Comet? Definition of Comet. Meaning of Comet. 10 February 2010 13:37 UTC www.knowledgerush.com [Source type: FILTERED WITH BAYES]

^ This gives substantial hope that it will now be possible to understand better the structure and composition of cometary nuclei, before the first cometary space missions perform in-situ measurements.
  • Chapter 18: Halley's and Other Comets 10 February 2010 13:37 UTC www.williams.edu [Source type: FILTERED WITH BAYES]

Pronunciation

Halley is generally pronounced /ˈhæli/, rhyming with valley, or /ˈheɪli/ rhyming with daily,[15] but Edmond Halley himself probably pronounced his name /ˈhɔːli/ Hawley, as in the word "hall".[16]

Computation of orbit

.Halley's Comet was the first to be recognized as periodic.^ P/Halley is named for Edmund Halley, the first person to recognise the periodicity of this comet.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ The first documented periodic comet, Halley, is properly named 1P/Halley.
  • Comet Facts - Explore the Cosmos | The Planetary Society 10 February 2010 13:37 UTC planetary.org [Source type: FILTERED WITH BAYES]

.Until the Renaissance, the philosophical consensus on the nature of comets, promoted by Aristotle, was that they were disturbances in the Earth's atmosphere.^ The greek philosopher Aristotle believed that comets existed in the Earth's atmosphere.
  • Leicester University Physics Department 10 February 2010 13:37 UTC www.star.le.ac.uk [Source type: FILTERED WITH BAYES]

^ C/1577 V1 "Great Comet of 1577" , observed by the great astronomer Tycho Brahe (and so determining that comets travel above the atmosphere of the Earth), comes third at -1.8 and C/1746 P1 is fourth.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ Comets were objects of much speculation among the early Greek astronomers, some of whom considered them to be planetary in nature, and others, such as Aristotle, considered them to be more of an atmospheric phenomena, such as meteors.
  • Solar System Exploration: Science & Technology: Science Features: View Feature 10 February 2010 13:37 UTC solarsystem.nasa.gov [Source type: FILTERED WITH BAYES]

.This idea was disproved in 1577 by Tycho Brahe, who used parallax measurements to show that comets must lie above the Moon.^ C/1577 V1 "Great Comet of 1577" , observed by the great astronomer Tycho Brahe (and so determining that comets travel above the atmosphere of the Earth), comes third at -1.8 and C/1746 P1 is fourth.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ The first real scientific facts known about comets were due to the observations of the great observer Tycho Brahe (1546-1601).
  • Solar System Exploration: Science & Technology: Science Features: View Feature 10 February 2010 13:37 UTC solarsystem.nasa.gov [Source type: FILTERED WITH BAYES]

^ He compared the lack of diurnal parallax of the comet of 1577 with the well-known parallax of the Moon (the diurnal parallax is the apparent change of position in the sky relative to the distant stars due to the rotation of the Earth).
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.However, many were still unconvinced that comets actually orbited the Sun, and assumed they must instead follow straight paths through the Solar System.^ Many comets cross Earth’s orbit as they approach the Sun.
  • Comet Facts - Explore the Cosmos | The Planetary Society 10 February 2010 13:37 UTC planetary.org [Source type: FILTERED WITH BAYES]

^ A comet is a small solar system body that orbits the Sun .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comets are small solar system bodies that orbit the Sun .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[17]
.In 1687, Sir Isaac Newton published his Principia, in which he outlined his laws of gravity and motion.^ Sir Isaac Newton used this comet's motion around the Sun to test Kepler's laws of planetary motion.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ The understanding of what comets were and how they worked received a boost when astronomer Edmund Halley used Isaac Newton's recently formulated theories on the motion of bodies and gravity to predict the course of a comet he observed in 1682.
  • The UnMuseum - Comet Halley 10 February 2010 13:37 UTC www.unmuseum.org [Source type: FILTERED WITH BAYES]

^ Orbit computation became possible with the publication in 1687 of Sir Isaac Newton's Principia , in which he produced the classical laws of physical motion for objects in the solar system.
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

However, his work on comets was decidedly incomplete. .Although he had suspected that two comets that had appeared in succession in 1680 and 1681 were in fact the same comet before and after passing behind the Sun (he was later found to be correct; see Newton's Comet),[18] he was unable to completely reconcile comets into his model.^ Sadly, Halley died before he could see if his prediction was correct but in late 1758, an amateur astronomer named Paltizsch recovered the comet which now bears Halley's name.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ Newton also complained to Halley about the fact that Halley doubted the scientific correctness of the biblical story of the creation.

^ Sir Isaac Newton used this comet's motion around the Sun to test Kepler's laws of planetary motion.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

.Ultimately, it was Newton's friend, editor and publisher, Edmond Halley who, in his 1705 Synopsis of the Astronomy of Comets, used Newton's new laws to calculate the gravitational effects of Jupiter and Saturn on cometary orbits.^ Named after: British scientist Edmond Halley, who first recognized it as a periodic comet and calculated its orbit .
  • Nothing but the facts about Halley's Comet 10 February 2010 13:37 UTC www.brighthub.com [Source type: General]

^ Halley's masterpiece on comets, A Synopsis of the astronomy of comets (Astronomiae cometicae) published in 1705 laid the foundation of modern cometary study.

^ In 1705 he published a pamphlet titled " A Synopsis of the Astronomy ".
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[19] .This calculation enabled him, after examining historical records, to determine that the orbital elements of a second comet which had appeared in 1682, were nearly the same as those of two comets which had appeared in 1531 (observed by Petrus Apianus) and 1607 (observed by Johannes Kepler).^ Those numbers above are just some of the orbital elements of comet Halley.
  • Comets Halley and Hale-Bopp 10 February 2010 13:37 UTC documents.wolfram.com [Source type: FILTERED WITH BAYES]

^ In 1682, he observed a bright comet.
  • Gravity, Part 2: Newton, Hooke, Halley and the Three Body Problem. 10 February 2010 13:37 UTC www.umich.edu [Source type: FILTERED WITH BAYES]

^ In 1682, another comet appeared to the world.
  • Geomagnetism and Edmond Halley (1656-1742) - GHN 10 February 2010 13:37 UTC www.ieeeghn.org [Source type: FILTERED WITH BAYES]

[19] .Halley thus concluded that all three comets were in fact the same object returning every 76 years, a period that has since been amended to every 75–76 years.^ This year brought on three bright comets.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Halleys comet Facts, information, pictures .
  • Halleys comet Facts, information, pictures | Encyclopedia.com articles about Halleys comet 10 February 2010 13:37 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]

^ Comet Halley (1P/Halley) is a periodic comet; it revisits our area of space approximately every 76 years.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

After a rough estimate of the perturbations the comet would sustain from the gravitational attraction of the planets, he predicted its return for 1758.[20]
.Halley's prediction of the comet's return proved to be correct, although it was not seen until 25 December 1758, by Johann Georg Palitzsch, a German farmer and amateur astronomer.^ He went on to predict that the comet would return in 1758.
  • The UnMuseum - Comet Halley 10 February 2010 13:37 UTC www.unmuseum.org [Source type: FILTERED WITH BAYES]

^ This comet was seen from early August to early December.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ As a consequence, it would return in 1758, he predicted.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.It did not pass through its perihelion until 13 March 1759, the attraction of Jupiter and Saturn having caused a retardation of 618 days.^ The perihelion of this apparition was on March 13, 1759.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Bright comets are generally a once-in-a-decade event and with two bright comets having passed, you would think comet hysteria would be an impossibility until after the millennium.
  • Comet Hysteria and the Millennium 10 February 2010 13:37 UTC cometography.com [Source type: FILTERED WITH BAYES]

^ View Hurricane Katrina from orbit, discover the cause of our aurora, then travel to our Moon, Mars, Jupiter, Saturn and Halley’s Comet.

[21] .This effect was computed (with a one-month error to 13 April)[22] by a team of three French mathematicians, Alexis Clairault, Joseph Lalande, and Nicole-Reine Lepaute,[23] previous to its return.^ Halley's predicted return date was later refined by a team of three French mathematicians: Alexis Clairaut , Joseph Lalande , and Nicole-Reine Lepaute , who predicted the date of the comet's 1759 perihelion to within one month's accuracy.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Edmond Halley - as well as a team of French mathematicians - predicted the return of this comet, not just from knowing the dates of its past visits, but by calculating the gravitational effects of planets like Saturn and Jupiter.
  • Comet Caesar - Dark Comet in 2012? 10 February 2010 13:37 UTC survive2012.com [Source type: FILTERED WITH BAYES]

^ The perihelion date of 1759 had been predicted with an accuracy of one month by Alexis-Claude Clairaut , a French astronomer and physicist.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.Halley did not live to see the comet again as he died in 1742.[24] The confirmation of the comet's return was the first time anything other than planets had been shown to orbit the Sun.^ AD :- Halley Comet return for the first time a predicted by Edmond Halley.

^ And see Halley's comet explode.

^ Its trajectory and the orbit of comet Halley are shown in Fig.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

It was also one of the earliest successful tests of Newtonian physics, and a clear demonstration of its explanatory power.[25]
.The possibility has been raised that 1st-century Jewish astronomers had already recognized Halley's Comet as periodic.^ A single line in the Talmud suggests that 1st century Jewish astronomers were also aware of the periodicy of Halley's Comet: .
  • Comet Caesar - Dark Comet in 2012? 10 February 2010 13:37 UTC survive2012.com [Source type: FILTERED WITH BAYES]

^ P/Halley is named for Edmund Halley, the first person to recognise the periodicity of this comet.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

This theory notes a passage in the Talmud [26] which refers to a "a star which appears once in seventy years that makes the captains of the ships err".[27]

Orbit and origin

The orbital paths of Halley, outlined in blue, against the orbits of Jupiter, Saturn, Uranus and Neptune, outlined in red
The orbit of Halley's Comet (blue) set against the orbits of the outer planets (red)
.Halley's orbital period over the last three centuries has been between 75 and 76 years, though it has varied between 74 and 79 years since 240 BC.[25][28] Its orbit around the Sun is highly elliptical, with an eccentricity of 0.967 (with 0 being a perfect circle and 1 being a parabolic trajectory).^ Orbital period: 75.32 years .
  • Nothing but the facts about Halley's Comet 10 February 2010 13:37 UTC www.brighthub.com [Source type: General]

^ Comet Halley’s period has irregularly varied between 74.4 years (from 1835 to 1910) and 79.6 years (from ad 451 to 530).
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Its orbital period is 2.74 days.

.The perihelion, the point in the comet's orbit when it is nearest the Sun, is just 0.6 AU[a] (between the orbits of Mercury and Venus), while its aphelion, or farthest distance from the Sun, is 35 AU (roughly the distance of Pluto).^ The point where (and when) an object orbiting the sun is closest to the sun.
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

^ That's roughly a 3% deviation between 2 orbits.
  • Comet Caesar - Dark Comet in 2012? 10 February 2010 13:37 UTC survive2012.com [Source type: FILTERED WITH BAYES]
  • Comet Ceasar and 2012 Doomsday 10 February 2010 13:37 UTC www.viewzone.com [Source type: FILTERED WITH BAYES]

^ The aphelion , furthest point from the Sun, is 35 AU, which is about how far Pluto is from the Sun.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

.Unusually for an object in the Solar System, Halley's orbit is retrograde; it orbits the Sun in the opposite direction to the planets, or clockwise from above the Sun's north pole.^ HELIOCENTRIC SYSTEM In the heliocentric model of the solar system , all the planets orbit around the Sun .

^ Orbit: Retrograde (opposite the direction of planetary orbits) .
  • Nothing but the facts about Halley's Comet 10 February 2010 13:37 UTC www.brighthub.com [Source type: General]

^ A comet is a small solar system body that orbits the Sun .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

.The orbit is inclined by 18° to the ecliptic, with much of it lying south of the ecliptic.^ Comet Halley's orbit is retrograde and inclined by 162_ with respect to the ecliptic plane.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

[29] .Due to Halley's highly eccentric orbit, it has one of the highest velocities, relative to the Earth, of any object in the Solar System.^ Using his theory of cometary orbits he calculated that the comet of 1682 (now called Halley's comet) was periodic and was the same object as the comet of 1531, and 1607.

^ Orbit computation became possible with the publication in 1687 of Sir Isaac Newton's Principia , in which he produced the classical laws of physical motion for objects in the solar system.
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

^ The comet's orbit dictated that it would never return to the inner solar system.
  • Stardust Memories: Frank E. Seagrave and Halley's Comet 10 February 2010 13:37 UTC www.theskyscrapers.org [Source type: Original source]

The 1910 passage was at a relative velocity of 70.56 km/s.[30] .Because its orbit comes close to Earth's in two places, Halley's Comet is the parent body of two meteor showers: the Eta Aquariids in early May, and the Orionids in late October.^ This is the parent comet to the Perseid meteor shower, which occurs in August.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Comet Wells was in the sky from late May to early July.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Halley's comet is the source of the Orionid shower in October.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

[31]
.Halley is classified as a periodic or short-period comet; one with an orbit lasting 200 years or less.^ Comet 6P/d’Arrest was one of the first short-period comets to be observed.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ Comet d’Arrest is in a short-period orbit with a period of 6.5 years.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

[32] .This contrasts it with long-period comets, whose orbits last for thousands of years.^ Comet d’Arrest is in a short-period orbit with a period of 6.5 years.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ Comets are heated for periods of years.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Hyakutake is a long period comet.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

.However, periodic comets have an average inclination to the ecliptic of only ten degrees, and an orbital period of just 6.5 years, so Halley's orbit is somewhat atypical.^ It's not just a comet he decided to name Halley.
  • second chances lyrics - Topic Powered By Madness! 1 February 2010 2:16 UTC boards.atlanticrecords.com [Source type: FILTERED WITH BAYES]

^ Comet d’Arrest is in a short-period orbit with a period of 6.5 years.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ Comets are heated for periods of years.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[25] .Most short-period comets (those with orbital periods shorter than 20 years and inclinations of 20–30 degrees or less) are called Jupiter family comets.^ Halley’s Comet is something of an irregularity for a short-period comet because they have an average orbit of 6.5 years and most of them have orbital periods shorter than 20 years.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comet d’Arrest is in a short-period orbit with a period of 6.5 years.
  • halley « The Transient Sky – Comets, Asteroids, Meteors 10 February 2010 13:37 UTC transientsky.wordpress.com [Source type: General]

^ Short-period comets are further divided into the Jupiter family (periods less than 20 years) and Halley family (periods between 20 and 200 years).
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

.Those like Halley, with orbital periods of between 20 and 200 years and inclinations extending from zero to more than 90 degrees, are called Halley-type comets.^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ Short-period comets are further divided into the Jupiter family (periods less than 20 years) and Halley family (periods between 20 and 200 years).
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ This comet had a tail that was a little more than 3 degrees long.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[32][33] .To date, only 54 Halley-type comets have been observed, compared with nearly 400 identified Jupiter family comets.^ Not only were thousands of observations of many types made from ground-based observatories, but for the first time in history, 2 comets - Halley's Comet and Comet Giacobini-Zinner - were met by a flotilla of spacecraft taking in situ measurements and transmitting them back to Earth.

^ His relatively realistic representation of a comet as the "Star of Bethlehem" in a frescoe dated 1304 was probably inspired by the appearance of comet Halley in 1301.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

^ Subsequent investigations have shown that Comet Halley has been observed at every passage since 240 BC. It was last seen in 1985-86.

[34]
.The orbits of the Halley-type comets suggest that they were originally long-period comets whose orbits were perturbed by the gravity of the giant planets and directed into the inner Solar System.^ The comet's orbit dictated that it would never return to the inner solar system.
  • Stardust Memories: Frank E. Seagrave and Halley's Comet 10 February 2010 13:37 UTC www.theskyscrapers.org [Source type: Original source]

^ See Makemake, our Solar System’s new dwarf planet and comet Halley.

^ Scientists believe that Halley-type comets used to be long-period comets until the gravity of the gas giants threw them into the inner Solar System .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[32] .If Halley was once a long-period comet, it is likely to have originated in the Oort Cloud,[33] a sphere of cometary bodies that has an inner edge of 20,000–50,000 AU.^ Hyakutake is a long period comet.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ P/Halley was the first comet shown to be periodic.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ Origin and evolution of comets - Formation of the Oort cloud .
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.Conversely the Jupiter family comets are believed to originate in the Kuiper belt,[33] a flat disc of icy debris between 30 AU (Neptune's orbit) and 50 AU from the Sun (in the scattered disc).^ Short-period comets are thought to originate in the Kuiper Belt , or associated scattered disc , which lie beyond the orbit of Neptune .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Their origin is the Kuiper belt of bodies beyond the orbit of planet Neptune.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

^ Short-period comets are thought to originate in the Kuiper Belt or the associated scattered disc, both of which lie beyond the orbit of Neptune .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

.However, another point of origin for the Halley-type comets has been proposed.^ However, that can't be the case because the events of the show take place during the last few years of the 1990's, and the latest appearance of Halley's comet was in 1986.
  • In awe of a star - Identifying the artwork in the opening Comet Sequence - Millennium Episode Related Article - Episode and Credits Guide 1 February 2010 2:16 UTC millennium-thisiswhoweare.net [Source type: General]

^ Here on Universe Today we have a great article about comets holding the secrets to the origins of life and another that lets you know the differences between asteroids and comets.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Type of Work: Dramatic work and accompanying music Registration Number / Date: PAu000369245 / 1981-12-03 Date of Creation: 1981 Title: Halley's comet : a play.
  • Halley's comet. By William F. Broidy Productions, Inc, Birds of prey, Volcanoes - song, music - Copyright Info 10 February 2010 13:37 UTC www.faqs.org [Source type: Reference]

.In 2008 a new trans-Neptunian object with a retrograde orbit similar to Halley's was discovered.^ View Hurricane Katrina from orbit, discover the cause of our aurora, then travel to our Moon, Mars, Jupiter, Saturn and Halley’s Comet.

^ C1 was being studied by Halley and was thought to be the same comet as 1532 because their orbit is so similar.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ This observation is a byproduct of a dedicated search [1] for small Trans-Neptunian Objects, a population of icy bodies of which more than 600 have been found during the past decade.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

.Nicknamed Drac, its orbit takes it from just outside that of Uranus to twice the distance of Pluto.^ The Great Comet of 1811 had an even greater perihelion distance (just outside the earth's orbit), but still displayed a tail at least 25 degrees long (or about a quarter of the way from the horizon to the zenith in the night sky).
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

^ Giacobini-Zinner is one of Jupiter's family of comets with its furthest point from the Sun being just outside Jupiter's orbit.

^ Uranus-Pluto conjunctions and oppositions might bring sudden and radical changes, like a cathartic diarrhoea, yet their full integration takes ages."
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

.It may be a member of a new population of small Solar System bodies that serves as the source of Halley-type comets.^ See Makemake, our Solar System’s new dwarf planet and comet Halley.

^ A comet is a small solar system body that orbits the Sun .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comets are small solar system bodies that orbit the Sun .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[35]
A meteor strikes the bottom left, while the Milky Way arcs overhead and a dawn-like light lines the lower horizon. The image was taken through a curved lens.
.
Orionid meteor striking the sky below the Milky Way and to the right of Venus.
^ Aristotle held this mechanism responsible for not only comets, but also meteors , the aurora borealis , and even the Milky Way .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

Zodiacal light is also seen at the image.
.Halley's Comet has probably been in its current orbit for 16,000 to 200,000 years, although it is not possible to numerically integrate its orbit for more than a few tens of apparitions, and close approaches before 837 can only be verified from recorded observations.^ More than 200 comets whose periods are between 3 and 200 years are known, however.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Number of recorded fatalities: 200,000."
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ A.D. Halley's Comet This was a close approach of Comet Halley and it was very bright at this time.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[36] .The non-gravitational effects can be crucial;[36] as Halley approaches the Sun, it expels jets of sublimating gas from its surface, which knock it very slightly off its orbital path.^ As the comet approaches the Sun, the crust absorbs heat and some of the ice begins to turn to gas.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ The perihelion is just 0.6 AU — that means after swinging by the Sun the comet makes it through Mercury's orbital path and almost to Venus (0.7 AU) before coming around again.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ When far from the sun in the outer reaches of the solar system, there is very little activity coming off such a nucleus.
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

.These orbital changes can cause deviations in its perihelion of up to four days.^ It was four days from full Moon but the bright gibbous moon was still causing significant interference and a slight haze did not help matters.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ These arcs also cause the (surprising) dark color of every comet we've seen up close.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ And then once one of these nightmares has some common details with a real catastrophe (which may be next day or four weeks later).
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

[37]
.In 1989, Boris Chirikov and Vitaly Vecheslavov performed an analysis of 46 apparitions of Halley's Comet taken from historical records and computer simulations.^ Some of the historical apparitions of Halley's Comet were as follows: .
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ The high public profile of Halley's Comet meant that many astronomical events were organised throughout the UK to coincide with its apparition.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

These studies showed that its dynamics were chaotic and unpredictable on long timescales.[38] .Halley's projected lifetime could be as long as 10 million years.^ Interestingly, some theologians have suggested that the star of Bethlehem in the Bible could be explained by the appearance of Halley's comet in the year 12 BC. .
  • In awe of a star - Identifying the artwork in the opening Comet Sequence - Millennium Episode Related Article - Episode and Credits Guide 1 February 2010 2:16 UTC millennium-thisiswhoweare.net [Source type: General]

^ The tail of C/1995 O1 was tens of millions of miles long in space, corresponding to 10 or more degrees long to the naked eye in very-dark-sky conditions.
  • Press Information Sheet for Comet C/1995 O1 10 February 2010 13:37 UTC sao-www.harvard.edu [Source type: FILTERED WITH BAYES]

^ Long-period comets have highly eccentric (elongated) orbits and periods ranging from 200 years to thousands or even millions of years.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

.More recent work suggests that Halley will evaporate, or split in two, within the next few tens of thousands of years, or will be ejected from the Solar System within a few hundred thousand years.^ However, that can't be the case because the events of the show take place during the last few years of the 1990's, and the latest appearance of Halley's comet was in 1986.
  • In awe of a star - Identifying the artwork in the opening Comet Sequence - Millennium Episode Related Article - Episode and Credits Guide 1 February 2010 2:16 UTC millennium-thisiswhoweare.net [Source type: General]

^ Interestingly, some theologians have suggested that the star of Bethlehem in the Bible could be explained by the appearance of Halley's comet in the year 12 BC. .
  • In awe of a star - Identifying the artwork in the opening Comet Sequence - Millennium Episode Related Article - Episode and Credits Guide 1 February 2010 2:16 UTC millennium-thisiswhoweare.net [Source type: General]

^ See Makemake, our Solar System’s new dwarf planet and comet Halley.

[33] .Observations by Hughes suggest that Halley's nucleus has been reduced in mass by 80–90% over the last 2000–3000 revolutions.^ For Whipple, a prograde rotation of the nucleus of P/Encke and a retrograde rotation of that of P/Halley could explain these observations.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

[14]

Structure and composition

A large, black, rock-like structure is visible amid an onrushing cloud of dust. A stream of brilliant white arcs up from the left.
The nucleus of Halley's Comet, imaged by the Giotto probe in 1986. The dark coloration of the nucleus can be observed, as well as the jets of dust and gas erupting from its surface.
.The Giotto and Vega missions gave planetary scientists their first view of Halley's surface and structure.^ The Giotto probe found that Comet Halley's nucleus reflects approximately 4% of the light that falls on it, and Deep Space 1 discovered that Comet Borrelly's surface reflects only 2.4% to 3% of the light that falls on it; by comparison, asphalt reflects 7% of the light that falls on it.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Scheduled for July 2005, Deep Impact's spacecraft will arrive at comet Tempel 1 and become the first mission to impact the surface of a comet.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Europe's first deep space mission was named Giotto after the artist who painted the comet as the Star of Bethlehem, after its appearance in 1301.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

.Like all comets, as Halley nears the Sun, its volatile compounds (those with low boiling points, such as water, carbon monoxide, carbon dioxide and other ices) begin to sublime from the surface of its nucleus.^ "The comet is like a point source.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The ice consists mainly of frozen water but may include other frozen substances, such as ammonia, carbon dioxide, carbon monoxide, and methane.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ This is the first time that water ice has been observed on the surface of a comet.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[39] .This causes the comet to develop a coma, or atmosphere, up to 100,000 km across.^ A comet coma is like a comet's atmosphere.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ While the solid nucleus of comets is generally less than 50 km across, the coma may be larger than the Sun, and ion tails have been observed to extend 1 astronomical unit (150 million km) or more.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Perihelion was on 09 February 1986, by which time the comet's velocity had increased to circa 150,000 km/hr.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

[3] .Evaporation of this dirty ice releases dust particles, which travel with the gas away from the nucleus.^ The nucleus of a comet is a ball of ice and rocky dust particles that resembles a dirty ice ball.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ "We believe that we see fragmentation of large dust lumps into swarms of small particles after they are coming out from the nucleus," Economou said.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The nucleus of a comet is made up of dust, ice, and small rocky particles.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

.Gas molecules in the coma absorb solar light and then re-radiate it at different wavelengths, a phenomenon known as fluorescence, whereas dust particles scatter the solar light.^ Coma and tails are ionized gas and charged dust particles that are interacting with the solar wind.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ This gas and dust forms the comet's coma.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Radiation from the sun pushes dust particles away from the coma.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

Both processes are responsible for making the coma visible.[11] .As a fraction of the gas molecules in the coma are ionized by the solar ultraviolet radiation,[11] pressure from the solar wind, a stream of charged particles emitted by the Sun, pulls the coma's ions out into a long tail, which may extend more than 100 million kilometers into space.^ Coma and tails are ionized gas and charged dust particles that are interacting with the solar wind.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ That is charges from the quasi-neutral plasma stream (solar wind) are separated!
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The ion tail is formed as a result of solar ultra-violet radiation acting on particles in the coma.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[39][40] .Changes in the flow of the solar wind can cause disconnection events, in which the tail completely breaks off from the nucleus.^ This leads to a "tail disconnection event".
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ This interaction of the solar wind with cometary ions is responsible for the often tens of millions of kilometre long blue ion tails of comets.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

^ The comet and its induced magnetic field form an obstacle to outward flowing solar wind particles.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

[13]
.Despite the vast size of its coma, Halley's nucleus is relatively small; barely 15 kilometers long, 8 kilometers wide and perhaps 8 kilometers thick.^ Small electric pulses of duration 10-15 ms of cometary origin were detected but are presently unexplained.Unexplaned by the plasma physics of comet coma and tails.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ A long tail of up to 100 degrees was reported, and small fragments have been observed to break off the main nucleus.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ The spacecraft found a roughly potato-shaped nucleus measuring about15 kilometers long.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[b] Its shape vaguely resembles that of an unshelled peanut.[3] .Its mass is relatively low; roughly 2.2 × 1014 kg,[4] and its average density is about 0.6 g/cm3, indicating that it is made of large number of small pieces, held together very loosely, forming a structure known as a rubble pile.^ Its average density is about 0.6 g/cm, indicating that it is very loosely constructed.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Himalia has a mass of 9.5 x 10 18 kg.

^ Its mass is extremely low; roughly 2.21014 kg.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[5] .Ground-based observations of coma brightness suggested that Halley's rotation period was about 7.4 days.^ A.D. Halley's Comet This was a bright appearance with a magnitude of about -7.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Among the comets with short enough periods to have been observed several times in the historical record, Comet Halley is unique in consistently being bright enough to be visible to the naked eye.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ The rotation pole position is 15.6 (3.7) degrees in right ascension and 16.4 (1.8) degrees in declination, which is consistent with ground-based and NEAR imaging team observations.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.However, images taken by the various spacecraft, along with observations of the jets and shell, suggested a period of 52 hours.^ "The images are even better than the impressive images of Comet Halley taken by Europe's Giotto spacecraft in 1986."
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[14] .Given the irregular shape of the nucleus, Halley's rotation is likely to be complex.^ Abstract: The nucleus of Comet 81P/Wild 2 is modeled by assuming various smooth triaxial ellipsoidal or irregular body shapes, having different rotational periods, spin axis orientations, and thermophysical properties.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[39] .Although only 25% of Halley's surface was imaged in detail during the flyby missions, they revealed an extremely varied topography, with hills, mountains, ridges, depressions, and at least one crater.^ The elongated nucleus shows pronounced topography with a mountain, ridges, flat planes, chains of hills (Fig.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

^ Ice/water was not detected during the Deep Impact mission, the images were of a cratered, rocky surface, like an asteroid.
  • Half Comet-Half Asteroid a Fluke? Nope | Universe Today 1 February 2010 2:16 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ They are often popularly described as "dirty snowballs", but recent observations have revealed dry dusty or rocky surfaces, suggesting that the ices are hidden beneath a crust .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[14]
.Halley is the most active of all the periodic comets, with others, such as Comet Encke and Comet Holmes, displaying activity one or two orders of magnitude weaker.^ Halley’s Comet , also known as Comet Halley, is the most well known periodic comet.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Chapter 18: Halley's and Other Comets Chapter 18: .
  • Chapter 18: Halley's and Other Comets 10 February 2010 13:37 UTC www.williams.edu [Source type: FILTERED WITH BAYES]

^ Comet Encke, a periodic comet with a short period.
  • Chapter 18: Halley's and Other Comets 10 February 2010 13:37 UTC www.williams.edu [Source type: FILTERED WITH BAYES]

[14] .Its day side (the side facing the Sun) is far more active than the night side.^ In a previous Picture of the Day article we noted that NASA scientists have determined that both of the Pioneer spacecraft are off course by more than a hundred thousand kilometers.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ So far the American team has the nose in front, because more than half that approximately 100 extra-solar planets was discovered of them.
  • The Contact Reports of "Billy" Eduard Albert Meier: a topical listing 1 February 2010 2:16 UTC www.theyfly.com [Source type: FILTERED WITH BAYES]

^ This comet was available to telescopes during the day rather than at night.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

.Spacecraft observations showed that the gases ejected from the nucleus were 80 percent water vapor, 17 percent carbon monoxide and 3 to 4 percent carbon dioxide,[41] with traces of hydrocarbons[42] although more recent sources give a value of 10 percent for carbon monoxide and also include traces of methane and ammonia.^ Much of the remainder is frozen carbon dioxide, methane, and ammonia.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Typical comet material includes water, methane and carbon dioxide.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The ice consists mainly of frozen water but may include other frozen substances, such as ammonia, carbon dioxide, carbon monoxide, and methane.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[43] .The dust particles were found to be primarily a mixture of carbon-hydrogen-oxygen-nitrogen (CHON) compounds common in the outer Solar System, and silicates, such as are found in terrestrial rocks.^ An extended tour of the outer Solar System.

^ Comet nuclei are known to range from about 100 meters to 40+ kilometers across and are composed of rock, dust, water ice, and frozen gases such as carbon monoxide , carbon dioxide , methane and ammonia .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Asteroids are also believed to have a different origin from comets, having formed in the inner Solar System rather than the outer Solar System.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

[39] .The dust particles decreased in size down to the limits of detection (~0.001 µm).^ Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[13] .The ratio of deuterium to hydrogen in the water released by Halley was initially thought to be similar to that found in Earth's ocean water, suggesting that Halley-type comets may have delivered water to Earth in the distant past.^ The ratio of deuterium (a heavy isotope of hydrogen) and hydrogen (D/H) in cometary water was found to be much higher than the typical value of material in the solar system and in particularly in the oceans of the earth.
  • Tumbling Stone 20 - The Giotto mission to Comet Halley 10 February 2010 13:37 UTC spaceguard.rm.iasf.cnr.it [Source type: FILTERED WITH BAYES]

^ The astronomers speculate that past impacts on Earth from such inner comets may have been an important source of the water now found in Earth's oceans (IFA press release and web site on main-belt comets; and Jewitt et al, 2006).
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ It is suspected that comet impacts have, over long timescales, also delivered significant quantities of water to the Earth's Moon , some of which may have survived as lunar ice .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

.However, subsequent observations showed Halley's deuterium ratio to be far higher than that in found in the Earth's oceans, making such comets unlikely sources for Earth's water.^ PIONEER-VENUS ORBITER - SIGNALS SENT TO SPACECRAFT TO POINT AT HALLEY'S COMET , with Moffett Field CA hand cancel, with SPACE VOYAGE two color printed cachet for event shows the spacecraft and Halley's Comet with text "Ultraviolet (UV) Spectrometer makes Halley's comet image.....to study comet's gas composition, water vaporization rate and gas to dust ratio" .
  • Price List - Halleys Comet Covers - JoeFrasketi's Space Covers /Joe Frasketi's Philatelic Space Covers 10 February 2010 13:37 UTC spacecovers.com [Source type: FILTERED WITH BAYES]

^ As predicted by Mark Twain in 1909 he would die with the next showing of Halley's comet and he did indeed pass away this year with the comet Halley in the sky.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Color printed cachet shows Halley's Comet passing over an observatory, with text (in spanish) saying " Return of Halley Comet 1985.
  • Price List - Halleys Comet Covers - JoeFrasketi's Space Covers /Joe Frasketi's Philatelic Space Covers 10 February 2010 13:37 UTC spacecovers.com [Source type: FILTERED WITH BAYES]

[39]
.Giotto provided the first evidence in support of Fred Whipple's "dirty snowball" hypothesis for comet construction; Whipple postulated that comets are icy objects warmed by the Sun as they approach the inner Solar System, causing ices on their surfaces to sublimate (change directly from a solid to a gas), and jets of volatile material to burst outward, creating the coma.^ Comets that travel in the inner solar system are believed to have been altered by heat from the sun.
  • Chapter 18: Halley's and Other Comets 10 February 2010 13:37 UTC www.williams.edu [Source type: FILTERED WITH BAYES]

^ This is the first time that water ice has been observed on the surface of a comet.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Any thoughts on the detection of ice on the surface of the comet?
  • Half Comet-Half Asteroid a Fluke? Nope | Universe Today 1 February 2010 2:16 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

Giotto showed that this model was broadly correct,[39] though with modifications. .Halley's albedo, for instance, is about 4 percent, meaning that it reflects only 4 percent of the sunlight hitting it; about what one would expect for coal.^ Its albedo (http://forums.randi.org/wiki/Albedo) is about 4 percent, meaning that only 4 percent of the sunlight hitting it is reflected; about what one would expect for coal.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The Templars were too attractive a target for even the Pope to ignore; else he considered that defending the Templars would bring about a head-on conflict that would only damage the Church.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ I have been writing about the Halley effect since 1989, but have only treated it as a theoretical possibility with a high degrees of anticipation.

[44] .Thus, despite appearing brilliant white to observers on Earth, Halley's Comet is in fact pitch black.^ Halley's Comet appeared in the late Fall.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Thus, despite appearing brilliant white to observers on Earth, Halley's comet is in fact pitch black.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Although Halley died 16 years before his prediction could be tested, the comet appeared on Christmas night 1758, right on schedule.
  • Comet | This Day In Tech | Wired.com 10 February 2010 13:37 UTC www.wired.com [Source type: General]

.The surface temperature of evaporating "dirty ice" ranges from 170 K (−103 °C) at higher albedo to 220 K (−53 °C) at low albedo; however Vega 1 found Halley's surface temperature to be in the realm of 300–400 K (30 to 130 °C).^ This scenario is compatible with the surface temperature of around 320 K and a temperature near 215 K for the sublimating ices.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ We said that the impact/electrical discharge will not reveal primordial dirty ice, but the same composition as the surface.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Deep Impact found ice on the surface of Tempel 1.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.This suggested only ten percent of Halley's surface was active, and that large portions of it were coated in a layer of dark dust, which retained heat.^ The nucleus is covered with a layer of dust, which retains heat.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The observation that the jets in comet Halley are active only on the sunward side implies a thin dust crust in the active areas.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Conveniently left out the little detail about the actual extent of the ice, which only covers ~ .0023% of the surface, in a thin layer, the remaining 99.9977% is dust.
  • Half Comet-Half Asteroid a Fluke? Nope | Universe Today 1 February 2010 2:16 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[13] Together, these observations suggested that Halley was in fact predominantly composed of non-volatile materials, and thus more closely resembled a "snowy dirtball" than a "dirty snowball".[14][45]

Apparitions

.Halley's calculations enabled the comet's earlier appearances to be found in the historical record.^ Halley's Comet This was a bright appearance.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ OASI opened the doors of Orwell Park Observatory on three occasions to enable the public to view Halley's Comet: .
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

.The comet may have been recorded in China as early as 467 BC, but this is uncertain.^ Comet Wells was in the sky from late May to early July.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ BC :- This is the first historic record ever of Halley comet's visit as reported by early Chinese historians.

^ Halley’s Comet has been observed since 240 B.C., although it may have been seen as early as 467 B.C. by astronomers in China.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[46] .The first certain observation dates from 240 BC, and subsequent appearances were recorded by Chinese, Babylonian, Persian, and other Mesopotamian texts.^ The most successful were Donald Yeomans at JPL in California, and Tao Kiang working in Ireland; in the early 1980s they managed to trace the comet back to 240 BC comparing historical records kept by ancient civilisations like the Babylonians and the Chinese.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Records of its observation go back to 690BC. Chinese astronomers recorded Halley's Comet on every apparition for over 2000 years from 240 BC to 1835 AD. (Until 1984, there was a missing observation from the Chinese record: the apparition of 164 BC. However, in 1984 astronomical historians deciphered a Babylonian tablet in the British Museum and found a description of a comet in 164 BC and also one of its next apparition in 87 BC: this had to be Halley's Comet!
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ BC :- This is the first historic record ever of Halley comet's visit as reported by early Chinese historians.

.The following table sets out the astronomical designations for every apparition of Halley's Comet from the earliest on record in 240 BC.[1] For example, "(1P/1982 U1, 1986 III, 1982i" indicates that for the perihelion in 1986, Halley's Comet was the first period comet known (designated 1P) and this apparition was the first seen in "half-month" U (the first half of November) in 1982 (giving 1P/1982 U1); it was the third comet past perihelion in 1986 (1986 III); and it was the ninth comet spotted in 1982 (provisional designation 1982i).^ Some of the historical apparitions of Halley's Comet were as follows: .
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ Halley’s Comet , also known as Comet Halley, is the most well known periodic comet.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ This comet is now known as Halley's Comet.

The perihelion dates of each apparition are shown.[47] .The perihelion dates farther from the present are approximate, mainly because of uncertainties in the modeling of non-gravitational effects.^ Non-gravitational force modeling of Comet 81P/Wild 2.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ By requiring that the model nuclei simultaneously reproduce certain properties of the empirical water production curve and non-gravitational changes of the orbit (focusing on changes of the orbital period and in the longitude of perihelion), constraints are placed on several properties of the nucleus.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.Perihelion dates 1607 and later are in the Gregorian calendar, while perihelion dates of 1531 and earlier are in the Julian calendar.^ Gregorian Calendar / England - "Replacing the Julian [Old Style] calendar, the Gregorian [New Style] calendar was adopted in England [1752], when it was necessary to drop 11 days.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

[48]
  • 1P/−239 K1, −239 (25 May 240 BC)
  • 1P/−163 U1, −163 (12 November 164 BC)
  • 1P/−86 Q1, −86 (6 August 87 BC)
  • 1P/−11 Q1, −11 (10 October 12 BC)
  • 1P/66 B1, 66 (25 January 66 AD)
  • 1P/141 F1, 141 (22 March 141)
  • 1P/218 H1, 218 (17 May 218)
  • 1P/295 J1, 295 (20 April 295)
  • 1P/374 E1, 374 (16 February 374)
  • 1P/451 L1, 451 (28 June 451)
  • 1P/530 Q1, 530 (27 September 530)
  • 1P/607 H1, 607 (15 March 607)
  • 1P/684 R1, 684 (2 October 684)
  • 1P/760 K1, 760 (20 May 760)
  • 1P/837 F1, 837 (28 February 837)
  • 1P/912 J1, 912 (18 July 912)
  • 1P/989 N1, 989 (5 September 989)
  • 1P/1066 G1, 1066 (20 March 1066)
  • 1P/1145 G1, 1145 (18 April 1145)
  • 1P/1222 R1, 1222 (28 September 1222)
  • 1P/1301 R1, 1301 (25 October 1301)
  • 1P/1378 S1, 1378 (10 November 1378)
  • 1P/1456 K1, 1456 (9 June 1456)
  • 1P/1531 P1, 1531 (26 August 1531)
  • 1P/1607 S1, 1607 (27 October 1607)
  • 1P/1682 Q1, 1682 (15 September 1682)
  • 1P/1758 Y1, 1759 I, 1758 (13 March 1759)
  • 1P/1835 P1, 1835 III, 1835c (16 November 1835)
  • 1P/1909 R1, 1910 II, 1909c (20 April 1910)
  • 1P/1982 U1, 1986 III, 1982i (9 February 1986)
  • Next perihelion predicted 28 July 2061

Prior to 66 AD

.
Observation of Haley's Comet, recorded in Cuneiform on a clay tablet between 22-28 September 164 BCE, Babylon, Iraq.
^ Interestingly, a couple of sites apparently copied from the other sites and just blatantly said the comet would strike sometime between July and September.
  • Comet Hysteria and the Millennium 10 February 2010 13:37 UTC cometography.com [Source type: FILTERED WITH BAYES]

^ However, the comet was brightening rapidly (forecast to reach magnitude 12.0 by mid-September) so the observers were enthusiastic about the prospects of securing an observation before too long.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ Great September Comet appeared between September 1882 and Mid-February of 1883.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

British Museum.
.The first certain appearance of Halley's Comet in the historical record is a description from 240 BC, in the Chinese chronicle Records of the Grand Historian or Shiji, which describes a comet that appeared in the east and moved north.^ Halley's Comet appeared in the late Fall.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ BC :- This is the first historic record ever of Halley comet's visit as reported by early Chinese historians.

^ This record of the comet was made by the Chinese and is the earliest comet record.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[49] .The only surviving record of the 164 BC apparition is found on two fragmentary Babylonian tablets, now owned by the British Museum.^ Babylonian skywatchers engraved a record of the next appearance of the comet in 164 BC on a cuneiform script tablet, which now resides in the British Museum .
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Records of its observation go back to 690BC. Chinese astronomers recorded Halley's Comet on every apparition for over 2000 years from 240 BC to 1835 AD. (Until 1984, there was a missing observation from the Chinese record: the apparition of 164 BC. However, in 1984 astronomical historians deciphered a Babylonian tablet in the British Museum and found a description of a comet in 164 BC and also one of its next apparition in 87 BC: this had to be Halley's Comet!
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ Catherine only served as Czarina from 1725-1727, but in these two short years the Academy was founded and became the greatest of Russian colleges."
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

[49]
.The apparition of 87 BC was recorded in Babylonian tablets which state that the comet was seen "day beyond day" for a month.^ The comet has been recorded by ancient Chinese astronomers as well as in Babylonian tablets around 87 B.C. The orbit of the comet is a rough ellipse with the perihelion , its closest point to the Sun , at 0.6 astronomical units (AU).
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Records of its observation go back to 690BC. Chinese astronomers recorded Halley's Comet on every apparition for over 2000 years from 240 BC to 1835 AD. (Until 1984, there was a missing observation from the Chinese record: the apparition of 164 BC. However, in 1984 astronomical historians deciphered a Babylonian tablet in the British Museum and found a description of a comet in 164 BC and also one of its next apparition in 87 BC: this had to be Halley's Comet!
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ When first detected, the comet was beyond the orbit of Jupiter and was too faint to be directly seen in visible light.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

[50] .This appearance may be recalled in the representation of Tigranes the Great, an Armenian king who is depicted on coins with a crown that features, according to V.G. Gurzadyan and R. Vardanyan, "a star with a curved tail [that] may represent the passage of Halley's Comet in 87 BC." Gurzadyan and Vardanyan argue that "Tigranes could have seen Halley's Comet when it passed closest to the Sun on Aug.^ That vapor is what is seen as the comets tail.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ This was also the first time an actual depiction of the comet was created; a coin featuring the comet on the crown of the Armenian king Tigranes II the Great (95 - 55 BC).
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Halley's Comet This was a bright appearance.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

.6 in 87 BC" as the comet would have been a "most recordable event"; for ancient Armenians it could have heralded the New Era of the brilliant King of Kings.^ The comet has been recorded by ancient Chinese astronomers as well as in Babylonian tablets around 87 B.C. The orbit of the comet is a rough ellipse with the perihelion , its closest point to the Sun , at 0.6 astronomical units (AU).
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ The most successful were Donald Yeomans at JPL in California, and Tao Kiang working in Ireland; in the early 1980s they managed to trace the comet back to 240 BC comparing historical records kept by ancient civilisations like the Babylonians and the Chinese.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Chaco Native Americans in New Mexico recorded this 1066 comet in their petroglyphs.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

[51]
.The apparition of 12 BC was recorded in the Book of Han by Chinese astronomers of the Han Dynasty who tracked it from August through October.^ BC :- This is the first historic record ever of Halley comet's visit as reported by early Chinese historians.

^ HALL, ASAPH Asaph Hall (1829-1907) was an American astronomer who discovered Mars ' two moons, Phobos and Deimos , on August 12, 1877, at the U. S. Naval Observatory's 26-inch refracting telescope .

^ Tang Dynasty / China - "The Tang dynasty [618-907] is regarded by historians as a high point in Chinese civilization - equal or even superior, to the Han period."
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

[10] .It passed within 0.16 AU of the Earth.^ By contrast, the comet passed at only 0.14 AU from the Earth in 1910.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

[52] .Halley's appearance in 12 BC, only a few years distant from the conventionally assigned date of the birth of Jesus Christ, has led some theologians and astronomers to suggest that it might explain the biblical story of the Star of Bethlehem.^ Astronomers have been looking at stars for a few years now.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The central expression, then, of the story of Demeter and Persephone is the Homeric hymn, to which Grote has assigned a date at least as early as six hundred years before Christ.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ Baktun 12 dates back to 1618 AD. This is the time period of Galeleo, Kepler, and Descartes, and indeed the birth of scientific materialism.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

.However, there are other explanations for the phenomenon, such as planetary conjunctions, and there are also records of other comets that appeared closer to the date of Jesus' birth.^ There are different kinds of comets; some are regular (periodic) and others fly by never to be seen again.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ You mean to say that comet's nuclei have no water, however, why are there jets observed coming from the nucleus?
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ It appeared the brain of such an experienced national leader, Saddam, was strongly and fatally affected by the comet energy...

[53]

66–989 AD

.If, as has been suggested, the reference in the Talmud to "a star which appears once in seventy years that makes the captains of the ships err"[54] (see above) refers to Halley's Comet, it may be a reference to the 66 AD appearance, because this passage is attributed to the Rabbi Yehoshua ben Hananiah.^ Halley's Comet appeared in the late Fall.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Sometime during the year of 1910 Comet Halley made an appearance.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ And see Halley's comet explode.

.This apparition was the only one to occur during ben Hananiah's lifetime.^ The independence of America occurred during one of the Halley's visits.

^ Among the comets that can easily be seen with the unaided eye, Comet Halley is the only one that returns in a single lifetime.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

[55]
The 141 AD apparition was recorded in Chinese chronicles.[56] .The 374 AD and 607 approaches each came within 0.09 AU of the Earth.^ The closest known passage to the Earth, 0.033 AU, occurred on April 9, ad 837.
  • comet (astronomy) :: Historical survey of comet observations and studies -- Britannica Online Encyclopedia 10 February 2010 13:37 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ AD: the comet's apparition was spectacular as it swept past the Earth on its closest ever approach, at a minimum distance only ten times that of the Moon.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

[52] .The 684 AD apparition was recorded in Europe in one of the sources used by the compiler of the 1493 Nuremberg Chronicles.^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

Chinese records also report it as the "broom star".[57]
.In 837, Halley's Comet may have passed as close as 0.03 AU (3.2 million miles; 5.1 million kilometers) from Earth, by far its closest approach.^ A.D. Halley's Comet This was a close approach of Comet Halley and it was very bright at this time.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ After its close approach to the Earth, the comet faded to about 2nd magnitude.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ As subsequent observations of the new comet were obtained, the IAU Central Bureau was able to compute the comet's orbital elements, and these computations indicated that the comet passed as close as 0.10 AU from the Earth on March 25, 1996!
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[52] .Its tail may have stretched 60 degrees across the sky.^ Its tail may have stretched 90 degrees across the sky.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ The comet traveled in the skies with a tail of about 40 degrees and had a magnitude of about -5.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Donati's comet C/1858 appeared Mid-August to November and had two brilliant tails about 60 degrees long.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

It was recorded by astronomers in China, Japan, Germany and the Islamic world.[10] .In 912, Halley's Comet is recorded in the Annals of Ulster, which state "A dark and rainy year.^ As predicted by Mark Twain in 1909 he would die with the next showing of Halley's comet and he did indeed pass away this year with the comet Halley in the sky.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Yes, Wild 2 has jets on the dark side wich you do concede after stating The observation that the jets in comet Halley are active only on the sunward side implies a thin dust crust in the active areas!
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

A comet appeared."[58]

1066

White embroidery showing several people on the left pointing to Halley, top right, over a tower
The comet's appearance in 1066 was recorded on the Bayeux Tapestry.
.In 1066, the comet was seen in England and thought to be an omen: later that year Harold II of England died at the Battle of Hastings; it was a bad omen for Harold, but a good omen for the man who defeated him, William the Conqueror.^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ In 811, Krum fought the Byzantines and defeated them in a great battle in which the Byzantine Emperor, Nicephorus I [who had become emperor in 802], lost his life.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ Pytor became Peter II in 1727 at age 14, but died one year later from smallpox."
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

.The comet is represented on the Bayeux Tapestry as a fiery star, and the surviving accounts describe it as appearing to be four times the size of Venus and shining with a light equal to a quarter of that of the Moon.^ It is shown on the Bayeux Tapestry, and the accounts which have been preserved represent it as having then appeared to be four times the size of Venus, and to have shone with a light equal to a quarter of that of the Moon.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ One very famous old recording of a comet is the appearance of Halley's Comet on the Bayeux Tapestry , which records the Norman conquest of England in AD 1066.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ It appeared that China had timely ridden the wave of Halley comet's stimulation and started an surge of constructive energies never known in human history.

.Halley came within 0.10 AU of the Earth at that time.^ All these young talents were born within the time period after Halley comet's arrival...

^ Interestingly, when Comet Halley reaches its largest distance from the Sun in December 2023, about 35 AU, it will only be 2.5 times fainter than it is now.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ This is because at the large distance of Comet Halley, the infalling sunlight is 800 times fainter than here on Earth.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

[52]
.This appearance of the comet is also noted in the Anglo-Saxon Chronicle.^ This appearance of the comet is also noted in the Anglo-Saxon Chronicle.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ The Anglo-Saxon Chronicle is begun."
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

.Eilmer of Malmesbury may have seen Halley previously in 989, as he wrote of it in 1066: "You've come, have you? ...^ What films had you seen in the days previously?
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ Having first seen it as a young boy in 989, Eilmer of Malmesbury declared prophetically in 1066: 'You've come, have you?…You've c—ome, you source of tears to many mothers, you evil.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ As far as I can determine there are no discharges seen in the images before the impact (you may be able to correct me).
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.You've come, you source of tears to many mothers, you evil.^ Having first seen it as a young boy in 989, Eilmer of Malmesbury declared prophetically in 1066: 'You've come, have you?…You've c—ome, you source of tears to many mothers, you evil.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ Someone asked how many times you've had a premonition and had it not come true.
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

I hate you! .It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country.^ It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ March 2007, 11:21 AM Now tell me what is more likely - that there is a static future, which a human brain is occasionally able to see with accuracy that creates magic feelings in you?
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ Had they been outgassing since then, they would have exhausted their ice supplies long ago and could not possibly be active now.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

I hate you!"[59]
The Irish Annals of the Four Masters recorded the comet as "A star [that] appeared on the seventh of the Calends of May, on Tuesday after Little Easter, than whose light the brilliance or light of the moon was not greater; and it was visible to all in this manner till the end of four nights afterwards."[58] Chaco Native Americans in New Mexico may have recorded the 1066 apparition in their petroglyphs.[60]

1145–1456

The 1145 apparition was recorded by the monk Eadwine. The 1986 apparition exhibited a fan tail similar to Eadwine's drawing.[57] .Some claim that Genghis Khan was inspired to turn his conquests toward Europe by the 1222 apparition.^ Later Europe was spared because Kublai Khan and his sons turned their interests towards China, where they finally settled down...

^ On the other hand, there was one leader, Genghis Khan, who was wise enough to drop all his conquest in Europe and settled down in China as emperor of Yuen dynasty.

[61] .The 1301 apparition may have been seen by the artist Giotto di Bondone, who represented the Star of Bethlehem as a fire-colored comet in the Nativity section of his Arena Chapel cycle, completed in 1305.[57] No record survives of the 1376 apparition.^ AD: the Florentine artist Giotto de Bandone immortalised the comet when he depicted it as the Star of Bethlehem in his painting of the Adoration of the Magi in the Arena Chapel, Padua.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ Chaco Native Americans in New Mexico recorded this 1066 comet in their petroglyphs.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ As far as I can determine there are no discharges seen in the images before the impact (you may be able to correct me).
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.In 1456, the Ottoman Empire invaded the Balkans, culminating in the Siege of Belgrade in July of that year and in a Papal Bull, Pope Calixtus III ordered special prayers be said.^ According to one story, first appearing in a posthumous biography in 1475 and later embellished and popularized by Pierre-Simon Laplace, Pope Callixtus III excommunicated the 1456 apparition of the comet, believing it to be an ill omen for the Christian defenders of Belgrade, who were at that time being besieged by the armies of the Ottoman Empire.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ Witches Condemned - "Pope Innocent VIII issued a papal bull condemning witches, which plunged Christian Europe into an orgy of bloody persecution which lasted nearly 250 years."
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ That year saw the passing of St John Capistran (Giovanni da Capistrano), also known as 'the soldier Saint', but Pope Calixtus III lived for another two years.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

In 1470 the humanist scholar Bartolomeo Platina wrote in his Lives of the Popes that,[62]
.A hairy and fiery star having then made its appearance for several days, the mathematicians declared that there would follow grievous pestilence, dearth and some great calamity.^ Why would you say this, given that there ARE billions of people who DO have several dreams each, every night?
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ Given that there are ~6 billion people having visions of the future all day and night Im sure that there are a lot of them who end up in a future they had a vision of in a (day)dream.
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ What difference in composition would there be between say a main belt comet and a short period comet and would there be a great difference between long period comets and the rest?
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.Calixtus, to avert the wrath of God, ordered supplications that if evils were impending for the human race He would turn all upon the Turks, the enemies of the Christian name.^ This order was issued by the Czar in 1772 because of the Jews' sharp business practices which had brought much misery upon the Christian population.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ So in order to judge the fit, we need to estimate all the different ways the event could have happened that would also have been accepted as a "hit".
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

.He likewise ordered, to move God by continual entreaty, that notice should be given by the bells to call the faithful at midday to aid by their prayers those engaged in battle with the Turk.^ If my theory is working, then it would be further confirmed if and when global temperatures should continue to drop noticeably in the next Winter seasons of 2008 and 2009...

Platina's account is not mentioned in official records.
.In the 18th century, a Frenchman further embellished the story, in anger at the Church, by claiming that the Pope had "excommunicated" Halley's Comet, though this story was most likely his own invention.^ Halley's Comet, like so many others, has been thought of in historical times as a bringer of doom and destruction.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ At 4,200 million km from the Sun, Comet Halley has now completed four-fifths of its travel towards the most distant point of this orbit.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ Halley’s Comet is something of an irregularity for a short-period comet because they have an average orbit of 6.5 years and most of them have orbital periods shorter than 20 years.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[63]

1531–1910

Black and white photograph of the comet, its nucleus brilliant white, and its tail very prominent, moving up and to the right
A photograph of Halley's Comet taken during its 1910 approach
.Halley's periodic returns have been subject to scientific investigation since the 16th century.^ Since the confirmation of Comet Halley's periodicity, many other periodic comets have been discovered through the telescope .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ Independent investigator, Anthony Peratt, has published many papers on the subject within IEEE -- the world's largest scientific institution.
  • Coma Halley APOP: Comet Halleys Nucleus: An Orbiting Ic 10 February 2010 13:37 UTC digg.com [Source type: FILTERED WITH BAYES]

.The three apparitions from 1531 to 1682 were noted by Edmond Halley, enabling him to predict its 1759 return.^ OASI opened the doors of Orwell Park Observatory on three occasions to enable the public to view Halley's Comet: .
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

^ Halley himself saw the comet in 1682, inspiring him to research the history of it.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Even now, Halley's Comet is the only bright comet whose apparitions can be predicted accurately.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

.Streams of vapour observed during the comet's 1835 apparition prompted astronomer Friedrich Wilhelm Bessel to propose that the jet forces of evaporating material could be great enough to significantly alter a comet's orbit.^ The non-gravitational forces are enough to alter comet orbits from one apparition to the next.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ A method for comets: Jets issued by comets alter their orbits.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Isn't this the first time we can observe any comet during its entire orbit?
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

[64]
.The 1910 approach, which came into view around 20 April, was notable for several reasons: it was the first approach of which photographs exist, and the first for which spectroscopic data were obtained.^ In early 1985, the UK 3.5m infrared telescope in Hawaii was first to detect Halley's Comet on its late 20 th Century passage around the Sun.
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

[13] .Furthermore, the comet made a relatively close approach of 0.15AU,[52] making it a spectacular sight.^ It is made up of the heated gases and dust that makes up the comet's nucleus.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ A.D. Halley's Comet This was a close approach of Comet Halley and it was very bright at this time.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ At the time of its discovery, the comet was in orbit around Jupiter, having been captured by the planet during a very close approach in 1992.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

.Indeed, on 18 May, the Earth actually passed through the tail of the comet.^ As predicted by Mark Twain in 1909 he would die with the next showing of Halley's comet and he did indeed pass away this year with the comet Halley in the sky.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ It is suspected that comet impacts have, over long timescales, also delivered significant quantities of water to the Earth's Moon , some of which may have survived as lunar ice .
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ It reached perihelion on May 1, 1996, brightening again and exhibiting a dust tail in addition to the gas tail seen as it passed the Earth.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

One of the substances discovered in the tail by spectroscopic analysis was the toxic gas cyanogen,[65] which led astronomer Camille Flammarion to claim that, when Earth passed through the tail, the gas "would impregnate the atmosphere and possibly snuff out all life on the planet."[66] His pronouncement led to panicked buying of gas masks and quack "anti-comet pills" and "anti-comet umbrellas" by the public.[67] .In reality, as other astronomers were quick to point out, the gas is so diffuse that the world suffered no ill effects from the passage through the tail.^ I'm merely pointing that out so that others might not get confused.
  • Coma Halley APOP: Comet Halleys Nucleus: An Orbiting Ic 10 February 2010 13:37 UTC digg.com [Source type: FILTERED WITH BAYES]

^ I'm merely pointing that out so that others might not get confused ...
  • Coma Halley APOP: Comet Halleys Nucleus: An Orbiting Ic 10 February 2010 13:37 UTC digg.com [Source type: FILTERED WITH BAYES]

^ It positioned itself between the dust tail, which followed the comet's trajectory, and the gas tail, which pointed away from the Sun.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[66]
.American satirist and writer Mark Twain was born on 30 November 1835, exactly two weeks after the comet's perihelion.^ Halley's Comet Mark Twain born on November 30th.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ As predicted by Mark Twain in 1909 he would die with the next showing of Halley's comet and he did indeed pass away this year with the comet Halley in the sky.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Mark Twain: A Biography by Albert Bigelow Pain (1912) Comet Halley was visible in 1835 and 1910 — uncannily coinciding exactly with the birth and death of Mark Twain (the pseudonym of Samuel Clemens).
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

In his autobiography, published in 1909, he said,
.I came in with Halley's Comet in 1835. It is coming again next year, and I expect to go out with it.^ It is coming again next year, and I expect to go out with it.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ I came in with Halley's Comet in 1835.
  • http://www.bbc.co.uk/dna/h2g2/A58436490 10 February 2010 13:37 UTC www.bbc.co.uk [Source type: FILTERED WITH BAYES]

^ Records of its observation go back to 690BC. Chinese astronomers recorded Halley's Comet on every apparition for over 2000 years from 240 BC to 1835 AD. (Until 1984, there was a missing observation from the Chinese record: the apparition of 164 BC. However, in 1984 astronomical historians deciphered a Babylonian tablet in the British Museum and found a description of a comet in 164 BC and also one of its next apparition in 87 BC: this had to be Halley's Comet!
  • OASI - Halley's Comet 10 February 2010 13:37 UTC www.ast.cam.ac.uk [Source type: FILTERED WITH BAYES]

.It will be the greatest disappointment of my life if I don't go out with Halley's Comet.^ A young Halley's comet with thousands of years of life ahead of it."

^ Take up station behind comet Halley in 1986 as its gaseous tail streams out near Earth.

^ "Computers don't go out to lunch," Stich agreed.

.The Almighty has said, no doubt: 'Now here are these two unaccountable freaks; they came in together, they must go out together.'^ "We believe that we see fragmentation of large dust lumps into swarms of small particles after they are coming out from the nucleus," Economou said.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ While there, they carried out what would now be called archaeological investigations, digging in and around the Temple.
  • 7th - 14th Century 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ They said that at greatest distance from the Sun (in what, over fifteen years from now?
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

[68]
Twain died on 21 April 1910, the day following the comet's subsequent perihelion.[69] The 1985 fantasy film The Adventures of Mark Twain was inspired by the quotation.
.Halley's 1910 apparition is distinct from the Great Daylight Comet of 1910, which surpassed Halley in brilliance and was actually visible in broad daylight for a short period, approximately four months before Halley made its appearance.^ Halley's Comet This was a bright appearance.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Halley comet's previous visit was in 1910.

^ Sometime during the year of 1910 Comet Halley made an appearance.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[70][71]

1986

Halley's Comet, tail barely visible, against a background of stars. The Milky Way is seen in the background.
Halley's Comet in 1986
Halley's 1986 apparition was the least favorable on record. .The comet and the Earth were on opposite sides of the Sun in February 1986, creating the worst viewing circumstances for Earth observers for the last 2,000 years.^ The Stardust spacecraft, launched in February 1999, collected particles from the coma of Comet Wild 2 in January 2004, and returned the samples to Earth in a capsule in January 2006.
  • Comet encyclopedia topics | Reference.com 10 February 2010 13:37 UTC www.reference.com [Source type: FILTERED WITH BAYES]

^ However, as the comet orbit becomes close to the sun, our earth would feel the increase of energy strongly, depending on the position of the ecliptic (what month) the earth is in at the time.

^ Take up station behind comet Halley in 1986 as its gaseous tail streams out near Earth.

[72] .Additionally, with increased light pollution from urbanization, many people never saw the comet at all.^ Comet Hale-Bopp was bright at -1 magnitude and even gave people in light polluted areas a lovely view, although not as grand as from dark skies.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Funny - you specifically remember that you have NEVER slowed down at a green light in all those years.
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

^ MondoAtheist 6th March 2007, 09:14 AM Funny - you specifically remember that you have NEVER slowed down at a green light in all those years.
  • Premonition? [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: Original source]

[73] .Further, the comet appeared brightest when it was almost invisible from the northern hemisphere in March and April.^ Great Comet lasted from mid-March to Mid April and had a tail 5 degrees long.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ The comet became a bright unaided-eye object and remained so in March, April and May in 1996.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comet Flaugergues appeared between April 1811 and January 1812.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[74] .Halley's approach was first detected by astronomers David Jewitt and G. Edward Danielson on 16 October 1982 using the 5.1 m Hale telescope at Mount Palomar and a CCD camera.^ Outlook After its passage in 1910, Comet Halley was again seen in 1982, when David Jewitt first observed its faint image with the 5-m Palomar telescope at a time when it was 11 AU from the Sun, a little further than planet Saturn.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ Contrary to popular belief, he didn't discover sunspots, but he was one of the first to observe them using a telescope.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ Peer deep into the cosmos through the focus of the Hale Telescope on Palomar Mountain.

[75] .The first person to visually observe the comet on its 1986 return was amateur astronomer Stephen James O'Meara on 24 January 1985. O'Meara used a home-built 24-inch telescope on top of Mauna Kea to detect the magnitude 19.6 comet.^ The Great Comet of 1831 was observed in January.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Contrary to popular belief, he didn't discover sunspots, but he was one of the first to observe them using a telescope.
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ In a survey of 300 asteroids lurking in the asteroid belt, the astronomers detected three objects that look a lot like comets ejecting little comet tails at times from their surfaces.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[76] .Stephen Edberg (then serving as the Coordinator for Amateur Observations at NASA's Jet Propulsion Laboratory) and Charles Morris were the first to observe Halley's Comet with the naked eye in its 1986 apparition.^ This was a naked-eye comet for the Southern Hemisphere.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

^ Outlook After its passage in 1910, Comet Halley was again seen in 1982, when David Jewitt first observed its faint image with the 5-m Palomar telescope at a time when it was 11 AU from the Sun, a little further than planet Saturn.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ Comet Bennett C/1969 Y1 was a naked eye object from February until Mid-May.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[77]
.The development of space travel allowed scientists the opportunity to study the comet at close quarters, and several probes were launched to do so.^ Isaac Newton thought that comets could travel in an orbit of some sort, but he never developed a solid model.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Scientists learned much about comets by studying Comet Halley as it passed near Earth in 1986.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ An especially important note about the 2001 apparition is that this comet became only the second comet to be photographed up close by a space probe, when Deep Space 1 flew about 1350 miles from the nucleus on September 22.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.The Soviet Vega 1 started returning images of Halley on 4 March 1986, and the first ever of its nucleus,[14] and made its flyby on 6 March, followed by Vega 2 making its flyby on 9 March.^ In fact, just look at the images of Halley's Comet nucleus (http://neo.jpl.nasa.gov/images/halley.html) from the Giotto spacecraft.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ It is made up of the heated gases and dust that makes up the comet's nucleus.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ "The images are even better than the impressive images of Comet Halley taken by Europe's Giotto spacecraft in 1986."
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

.On 14 March, the Giotto space probe, launched by the European Space Agency, made the closest pass of the comet's nucleus.^ Remember it's moving at 10,281 meters per second http://www.thunderbolts.info/tpod/2008/image08/081022filaments.jpgInfrared image of Holmes 17P. Credit: NASA/JPL-Caltech http://apod.nasa.gov/apod/image/0610/swan_rheman.jpgCredit & Copyright: Michael Jger & Gerald Rhemann The European Space Agency's Giotto probe met Halley's Comet on March 16, 1996.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The nucleus of a comet is made up of dust, ice, and small rocky particles.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ The probe found that a comet's nucleus can have mountains , valleys, and smooth plains.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[14] There were also two Japanese probes, Suisei and Sakigake. The probes were unofficially known as the Halley Armada.[78]
.Based on data retrieved by Astron, the largest ultraviolet space telescope of the time, during its Halley's Comet observations in December 1985, a group of Soviet scientists developed a model of the comet's coma.^ December 31st, 2009 Halley's Comet .
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Outlook After its passage in 1910, Comet Halley was again seen in 1982, when David Jewitt first observed its faint image with the 5-m Palomar telescope at a time when it was 11 AU from the Sun, a little further than planet Saturn.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ The electrical model suggests the likelihood of an electrical discharge between the comet nucleus and the copper projectile, particularly if the comet is actively flaring at the time.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[79] The comet was also observed from space by the International Cometary Explorer. .Originally International Sun-Earth Explorer 3, the probe was renamed and freed from its L1 Lagrangian point location in Earth's orbit to intercept comets 21P/Giacobini-Zinner and Halley.^ The comet has been recorded by ancient Chinese astronomers as well as in Babylonian tablets around 87 B.C. The orbit of the comet is a rough ellipse with the perihelion , its closest point to the Sun , at 0.6 astronomical units (AU).
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ At 4,200 million km from the Sun, Comet Halley has now completed four-fifths of its travel towards the most distant point of this orbit.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ However, as the comet orbit becomes close to the sun, our earth would feel the increase of energy strongly, depending on the position of the ecliptic (what month) the earth is in at the time.

[80]
.Two Space Shuttle missions—the ill-fated STS-51-L (ended by the Challenger disaster)[81] and STS-61-E—were scheduled to observe Halley's Comet from low Earth orbit.^ Halley comet's last arrival was at end of 1985.

^ Solar activity may cut tails in two but there have been no observations of comets tuunring off during low solar activity.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ At 4,200 million km from the Sun, Comet Halley has now completed four-fifths of its travel towards the most distant point of this orbit.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

.STS 61-E was a Challenger mission scheduled for March 1986, carrying the ASTRO-1 platform to study the comet.^ Scheduled for July 2005, Deep Impact's spacecraft will arrive at comet Tempel 1 and become the first mission to impact the surface of a comet.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Scientists learned much about comets by studying Comet Halley as it passed near Earth in 1986.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Comet 1982 was at perihelion until March 1986.
  • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

[82] The mission was canceled, and ASTRO-1 would not fly until late 1990 on STS-35.[83]

After 1986

Grainy, white-on-black image showing Halley as a barely distinguishable black dot
Halley's Comet at 28 AU Heliocentric Distance
.On 12 February 1991, at a distance of 14.4 AU from the Sun, Halley underwent an outburst that lasted for several months, releasing a cloud of dust 300,000 km across.^ As you know, plenty of comets exhibit 'cometary' behaviour well beyond 60 million km from the Sun (the approx radius of Mercury's orbit); in particular, they are active at about 1 au, and even at Mars' distance.
  • Half Comet-Half Asteroid a Fluke? Nope | Universe Today 1 February 2010 2:16 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ Chinese Naval Expeditions - "In 1405, Cheng Ho set forth with 300 ships and 12,000 men and visited Southeast Asia, Indonesia, and Ceylon."
  • 1394-1890 1 February 2010 2:16 UTC mirrorh.com [Source type: FILTERED WITH BAYES]

^ There is nothing wrong with our mainstream model :eusa_snooty: Energy from the Sun -- insolation - was stored in the dust cover and the nucleus within the months before the outburst.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

[39] .Halley was most recently observed in 2003 by three of the Very Large Telescopes at Paranal, Chile, when Halley's magnitude was 28.2. The telescopes observed Halley, at the faintest and furthest any comet has ever been imaged, in order to verify a method for finding very faint trans-Neptunian objects.^ Outlook After its passage in 1910, Comet Halley was again seen in 1982, when David Jewitt first observed its faint image with the 5-m Palomar telescope at a time when it was 11 AU from the Sun, a little further than planet Saturn.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ Similar TNO-surveys have been performed before, but this is the first time that several very large telescopes are used simultaneously in order to observe extremely faint, hitherto inaccessible objects.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ At 4,200 million km from the Sun, Comet Halley has now completed four-fifths of its travel towards the most distant point of this orbit.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

[9] .Astronomers are now able to observe the comet at any point in its orbit.^ The comet has been recorded by ancient Chinese astronomers as well as in Babylonian tablets around 87 B.C. The orbit of the comet is a rough ellipse with the perihelion , its closest point to the Sun , at 0.6 astronomical units (AU).
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

^ It is now well established that gas from comets is ionized by several processes and joins the solar wind2, forming an ion (plasma) tail that points away from the Sun.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ This means that with the VLT, for the first time in the long history of this comet, the astronomers now possess the means to observe it at any point in its 76-year orbit!
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

[9]
.The next predicted perihelion of Halley's Comet is 28 July 2061,[2] when it is expected to be better positioned for observation than during the 1985–1986 apparition, as it will be on the same side of the Sun as Earth.^ Outlook After its passage in 1910, Comet Halley was again seen in 1982, when David Jewitt first observed its faint image with the 5-m Palomar telescope at a time when it was 11 AU from the Sun, a little further than planet Saturn.
  • Comet Halley spotted at 4200 million km - Bad Astronomy and Universe Today Forum 10 February 2010 13:37 UTC www.bautforum.com [Source type: General]

^ The observation that the jets in comet Halley are active only on the sunward side implies a thin dust crust in the active areas.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Halley comet's last arrival was at end of 1985.

[28] It is expected to have an apparent magnitude of −0.3, compared with only +2.1 for the 1986 apparition.[84] .On 9 September 2060, Halley will pass within 0.98 AU of Jupiter, and then on 20 August 2061, pass within 0.0543 AU (8.1 million kilometers) of Venus.^ All these happened within 20 years after the Halley visit.

[85] .In 2134, Halley is expected to pass within 0.09 AU (13.6 million kilometers) of the Earth.^ "Forbidden lines" are spectral signatures that are not expected in space because here on Earth they are found only within strong electric fields.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ The Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 3830 kilometers of asteroid 433 Eros on 23 December 1998.
  • The Electric Comet theory [Archive] - JREF Forum 1 February 2010 2:16 UTC forums.randi.org [Source type: FILTERED WITH BAYES]

^ Scientists learned much about comets by studying Comet Halley as it passed near Earth in 1986.
  • Comet | Universe Today 10 February 2010 13:37 UTC www.universetoday.com [Source type: FILTERED WITH BAYES]

[85] Its apparent magnitude is expected to be −2.0.[84]

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  85. ^ a b "JPL Close-Approach Data: 1P/Halley". Jet Propulsion Laboratory. 1994-01-11 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1P;orb=0;cov=0;log=0;cad=1#cad. Retrieved 2009-05-05. 

Bibliography

  • P. Lancaster-Brown (1985). Halley & His Comet. Blandford Press. ISBN 0713714476. 
  • C. Sagan and A. Druyan (1985). Comet. Random House. ISBN 0-394-54908-2. 

External links

Periodic Comets (by number)
Previous
(periodic comet navigator)
1P/Halley Next
2P/Encke
List of periodic comets

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

English

Etymology

.(Circa 1758) Named for Edmond Halley, the English astronomer who first computed its orbit and established its periodicity (observations of individual passages date back at least to 240 B.C.).^ P/Halley is named for Edmund Halley, the first person to recognise the periodicity of this comet.
  • SkyEye - Comets 10 February 2010 13:37 UTC www.obliquity.com [Source type: FILTERED WITH BAYES]

^ Edmond Halley was the first person to recognise that this comet was periodic.

^ Halley's comet is named for Edmond Halley, an English astronomer.
  • Results: Halley's Comet 10 February 2010 13:37 UTC search.nasa.gov [Source type: FILTERED WITH BAYES]

.Halley predicted the return of the comet (then last seen in 1682) in 1705; when it did return in late 1758, it quickly acquired this name.^ It did, and now bears his name: Halley's Comet.
  • Comets 10 February 2010 13:37 UTC burro.astr.cwru.edu [Source type: FILTERED WITH BAYES]
  • Comets 10 February 2010 13:37 UTC filer.case.edu [Source type: FILTERED WITH BAYES]

^ Halley's Comet returned, as he predicted, in 1758, 15 years after his death.
  • Who Was Edmund Halley? (Cosmology: Ideas) 10 February 2010 13:37 UTC www.aip.org [Source type: FILTERED WITH BAYES]

^ Although he did not live to see it, his prediction was correct, and the comet was named Halley's comet.
  • Comet - body, water, Earth, life, gas, system, carbon, surface, part, Age-old fascination, Halleys comet, Comet Hale-Bopp 10 February 2010 13:37 UTC www.scienceclarified.com [Source type: FILTERED WITH BAYES]

Pronunciation

  • IPA: /ˌhæli:z ˈkɒmɪt/, /ˌheɪli:z ˈkɒmɪt/

Proper noun

Singular
Halley's Comet
Plural
-
.
  1. A very bright comet which can be seen every 75-76 years.^ This year brought on three bright comets.
    • Comet list Compiled by Christie POnder 10 February 2010 13:37 UTC www.weatherfriend.com [Source type: FILTERED WITH BAYES]

    ^ Comet Halley has a period of 76 years.
    • Build You Own Comet 10 February 2010 13:37 UTC www.noao.edu [Source type: FILTERED WITH BAYES]

    ^ Halley’s Comet appears every 75 to 76 years.
    • Science Facts » Marvel in the Sky: Halley’s Comet 10 February 2010 13:37 UTC www.science-facts.com [Source type: FILTERED WITH BAYES]
    • Science Facts » 2007 » June 10 February 2010 13:37 UTC www.science-facts.com [Source type: FILTERED WITH BAYES]

    .
    • In the London papers of May 3 we have the following accounts […] It had a short broad tail in a direction opposite the sun ; as Dr Halley's comet ought to have ; being much foreshortened […] — The Scots Magazine, Vol.^ The nucleus of Comet Halley , far from being ...
      • Article: Halley's Comet is coming. - Saturday Evening Post | HighBeam Research - FREE trial 10 February 2010 13:37 UTC www.highbeam.com [Source type: Academic]

      ^ The tail of a comet will always be anti-sunward (away from the sun), not opposite the direction of comet motion.
      • Build You Own Comet 10 February 2010 13:37 UTC www.noao.edu [Source type: FILTERED WITH BAYES]

      ^ The tail always points away from the Sun -- not away from the comet’s direction of motion.
      • Comet Facts - Explore the Cosmos | The Planetary Society 10 February 2010 13:37 UTC planetary.org [Source type: FILTERED WITH BAYES]

      XXI (April 1759), p. 208

Synonyms

Translations

  • French: comète de Halley f.

Simple English

[[File:|thumb|Comet Halley]]

Halley's Comet (Comet Halley) is a comet which comes round every 75 or 76 years. When it is near, it can be seen with the naked eye. It will return in 2061.

The comet is named after Edmond Halley (1656–1742), an English astronomer, who predicted the comet's return. Halley's Comet was the first comet to be recognized as periodic.

When the comet came close to the Earth in 1986, it was visited by several space-probes. The probe Giotto from the European Space Agency managed the closest approach to the comet.

Other pages


Citable sentences

Up to date as of December 30, 2010

Here are sentences from other pages on Halley's Comet, which are similar to those in the above article.








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