Great Rift (astronomy)
In astronomy, the Great Rift (sometimes called the Dark Side, Dark Rift, or, less commonly, Dark River) is a series of overlapping, non-luminous, molecular dust clouds that are 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 plasma and dust.
Starting at the constellation of Cygnus, where it is known as the Cygnus Rift or Northern Coalsack, the Great Rift stretches to Aquila; to Ophiuchus, where it broadens out; to Sagittarius, where it obscures the Galactic Center; and finally to 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 Earth. A similar dark band can be seen in edge-on distant galaxies, such as NGC 891 in Andromeda.
Radio image showing intense radio emissions emanating from the center of the Milky Way.
See also 
- "The Great Rift". Encyclopædia Britannica Online. 2009. Retrieved 2009-04-25.
- "Great Rift". Sci-Tech Dictionary:. Retrieved 2009-04-25.
- Kaler, Jim. "The Milky Way - From STARS". University of Illinois at Urbana-Champaign. Department of Astronomy. pp. Maps 2 and 5. Retrieved 2009-04-25.
- Dark River, Wide Field by Rogelio Bernal Andreo, at APOD