Coalsack

The Coalsack Dark Nebula, or simply the Coalsack, is the most prominent dark nebula in the sky. Near Alpha Crucis in the constellation of Crux, it measures 7 degrees by 5 degrees, and is easily visible to the naked eye as a dark patch silhouetted against the southern Milky Way. It appears as a 'hole in the Milky Way'. At a distance of about 600 light years, this is a huge dark nebula measuring 70 light years in diameter.

The Coalsack Dark Nebula overlaps somewhat into the neighbor constellations Centaurus and Musca. Although this nebula was known to the people of the Southern Hemisphere in prehistoric times, its first observation was reported by Vincente Yanez Pinzon in 1499. The Coalsack is not present in the New General Catalogue and does not have an identification number.