Astronomy Picture of the Day

Explanation: Face-on spiral galaxy NGC 6946 and open star cluster NGC 6939 sharethis cosmic snapshot,composed with over 68 hours of image data capturedwith a small telescope on planet Earth.The field of view spans spans about 1 degreeor 2 full moons on the sky toward the northern constellationCepheus.Seen through faint interstellar dust couds near the plane of ourMilky Way galaxy, the stars ofopen cluster NGC 6939are 5,600 light-years in the distance, near bottom right in the frame.Face-on spiral galaxy NGC 6946is at top left, but lies some 22 million light-years away.In the last 100 years, 10 supernovae have been discoveredin NGC 6946,the latest one seenin 2017.By comparison, the average rate of supernovae in our Milky Way is about 1every 100 years or so.Of course, NGC 6946 is also known as The Fireworks Galaxy.