NGC 6939 is an open star cluster located in the constellation Cepheus. It is approximately 3,600 light-years away from Earth and contains around 50 stars. The cluster is estimated to be about 1 billion years old and is notable for its relatively loose structure compared to other star clusters. Discovered by William Herschel in 1788, NGC 6939 is best observed with binoculars or small telescopes. Its stars are spread out over a region of about 10 arcminutes in diameter, making it a beautiful sight in the night sky, especially for amateur astronomers.