Messier 23 is an open star cluster located in the constellation Sagittarius. It was discovered by the astronomer Charles Messier in 1764 and is approximately 2,200 light-years away from Earth. The cluster contains around 150 stars, with its brightest members being of magnitude 9. The age of Messier 23 is estimated to be about 220 million years. It spans roughly 25 light-years in diameter and is best observed with binoculars or small telescopes. This cluster is a beautiful example of the stellar formations found in our galaxy, the Milky Way.