M 17 has lots of names. It is known as Omega, Swan, Horseshoe or Lobster Nebula . In small scopes the nebula appears like the tail of a comet. At one side some stars are sprinkling. They build a mini cluster and belong to the nebula.
Larger telescopes reveal a looped shape.
This structure can only be seen with large telescopes. Small scopes just show the bright stars in the heart of the nebula. The planetary nebula NGC6818 shows an irregular oval shape. The open star cluster M 18 appears loose for the 20 cluster members a scattered over a region of 0.2 degrees in the sky. Therefore its best viewed with binoculars or small scopes.