Messier 18 or M18, also designated NGC 6613, is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Sagittarius Star Cloud (M24).
Messier 18 is 1,296 pc (parsecs) from the Earth and 6,830 pc from the Galactic Center. It is orbiting the Milky Way core with a period of 186.5 million years and an eccentricity of 0.02. This carries it to as close as 6.5 kpc to, and as far as 6.8 kpc from the galactic core. It passes vertically through the galactic plane once every 27.4 million years, ranging no more than 80 pc above or below.