Sagittarius star cloud, optical image. The Sagittarius star cloud (also known as Delle Caustiche, M24 or IC 4715) is the largest and most dense star cloud visible in the night sky, spanning about 600 light years across. There are many types of stars and nebulae seen here. The pink region at lower centre is the emission nebula IC 1284 and slightly to its lower right is NGC 6590, a reflection nebula. Towards the upper right corner are dark nebula patches, made from clouds of dense dust. The Sagittarius star cloud holds millions of stars and is located about 10,000 light years from Earth, in the constellation Sagittarius.