Located in the
constellation Cygnus, M39 is a very loose cluster of about 30
stars. It lies only 800 light-years from Earth, which makes it
one of the closest open clusters in the sky. The cluster has a
diameter of about 7 light-years, and is believed to be over 250
million years old. With a visual magnitude of 5.2, it is a
bright cluster although very loosely populated. This cluster is
an easy target for binoculars and is best observed in telescopes
at low power.
