The Lagoon Nebula (catalogued as Messier 8 or M8, and as NGC 6523) 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 Guillaume Le Gentil in 1747 and is one of only two star-forming nebulae faintly visible to the naked eye from mid-northern latitudes. (Wikipedia)