M39 - NGC 7092

Messier 39 (NGC 7092) is a large, bright, and sparse open cluster in the constellation Cygnus, located approximately 825 light-years from Earth, making it one of the nearest Messier objects. The cluster contains roughly 30 stars within a diameter of about 7 light-years and shines at a combined apparent magnitude of about 4.6, easily visible to the naked eye under dark skies. M39 is estimated to be around 230 to 300 million years old. The cluster was possibly known to Aristotle around 325 BC, who may have mentioned it as a cometary object, though this identification is uncertain. It was independently observed by Guillaume Le Gentil in 1750 and cataloged by Messier in 1764. M39's proximity means that its member stars are widely spread across about 32 arcminutes of sky, making it best suited for binoculars or very low-power telescope views. Through binoculars, it resolves into a loose triangular arrangement of about two dozen stars of 7th to 10th magnitude, set against the rich Milky Way backdrop of Cygnus. At higher magnification in a telescope, the cluster tends to fill the field and lose its identity, so observers should resist the temptation to increase power. M39 is located about 9 degrees east-northeast of the brilliant star Deneb (Alpha Cygni) and lies in one of the richest parts of the Milky Way. While it is not a dramatic or dense cluster, its brightness and easy visibility make it a pleasant target for casual stargazing, and it is often recommended as a beginner's object. The cluster's young-to-intermediate age means its stars are still primarily on the main sequence, with the brightest being A0-type stars.

Contains about 30 stars spanning 7 light-years at only 825 light-years distance, one of the nearest Messier objects, spanning 32 arcminutes of sky.