M17 was dicovered 1745 or 1746 by Ph. Loys de Cheseaux. Just about 5,700 light years away M17 is a huge and active region of star creation located in the constellation of Sagittarius. The bright center of the emission nebula is formed like a swan, therefore the object is also called Swan nebula. West of the swan's neck a very young star cluster containing about 2,000 stars is mainly hidden in the dust. Only very few brigt giant stars are currently visible. Star creation proceeds in the dark regions of the nebula until today. The object is surrounded by a major molecular cloud that can not be seen in the visible light. As the neighbored Eagle nebula (M16), M17 resides in the Perseus arm of our galaxy and forms one of the most luminant HII regions known in our galaxy. The glowing region spans about 70x50 light-years.