The Trifid Nebula is located in the constellation Sagittarius and is a combination of a reflection nebula, an emission nebula and a dark nebula in the centre with the catalogue designation Messier 20. The other prominent feature in the region is Messier 21, an open star cluster. These objects can be seen low on the horizon from the northern hemisphere in summer. The objects are both about 4'000 light years from the solar system. 

Messier 21 is about 6.6 million years old, relatively young for an open star cluster.