The Lagoon Nebula (catalogued as Messier 8, NGC 6523, Sharpless 25, RCW 146, and Gum 72) is a giant interstellar cloud in the constellation Sagittarius. It is classified as an emission nebula and as an H-II region. The Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star forming nebulae faintly visible to the eye from mid-northern latitudes.