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The Milky Way near Cygnus showing the dark lane of the Great Rift

In astronomy, the Great Rift, sometimes called the Dark Rift, is a series of overlapping non-luminous molecular dust clouds located between the solar system and the Sagittarius Arm of the Milky Way Galaxy at a distance of about 100 parsecs or about 300 light years (2×10¹⁵ miles or 3×10¹⁵ kilometers) from Earth. The clouds are estimated to contain about 1 million solar masses of gas.

To the naked eye they seem to divide the bright band of the Milky Way lengthwise through about one-third of its extent forming a sort of dark lane, flanked by lanes of numerous stars.

Starting at the constellation of Cygnus, where it is known as the Cygnus Rift or Northern Coalsack, the rift reaches through Aquila into Ophiuchus, where it broadens out, and on into Sagittarius, where it obscures the centre of the Galaxy, and finally finishes in Centaurus. One of the most important regions it obscures is the Cygnus OB2 association, a large cluster of young stars and one of the largest regions of star formation near the Earth.

A similar dark band can be seen in edge-on distant galaxies such as NGC 891 in Andromeda. ^[1]

See also

• Dark-cloud constellations

Notes

References

• "The Great Rift". Encyclopedia Britannica Online. 2009. http://www.britannica.com/EBchecked/topic/243658/Great-Rift. Retrieved 2009-04-25.  
• "Great Rift". Sci-Tech Dictionary:. http://www.answers.com/topic/great-rift. Retrieved 2009-04-25.  
• ""Great Rift."". A Dictionary of Astronomy.. Encyclopedia.com.. 1997.. http://www.encyclopedia.com. Retrieved 2009-04-25.  
• Kaler, Jim. "The Milkey Way As Seen from the Northern Hemisphere From STARS". University of Illinois at Urbana-Champaign. Department of Astronomy. pp. Maps 2 and 5. http://www.astro.illinois.edu/~jkaler/sow//mw.html. Retrieved 2009-04-25.