The diffuse nebula M8 in Sagittarius, also known as NGC 6523. It is about 1½° long and ½° wide. The Lagoon Nebula gets its name from a dark lane that divides it in two. The brightest part of the nebula is called the Hourglass. The Lagoon Nebula contains the 5th-magnitude star cluster NGC 6530. The main illumination of the nebula comes not from this cluster but from the 6th-magnitude blue supergiant 9 Sagittarii. The Lagoon Nebula lies 5000 l.y. away.
Subjects: Astronomy and Astrophysics.