Messier 21. NGC 6531

Click on the image for a full resolution version         See this image also on Instagram     Messier 21 is a very young open cluster (just 4.6 million years old), located 3,900 light years away in the constellation Sagittarius. Although it is not bright enough to have naked eye visibility, M21 is a fine … Continue reading Messier 21. NGC 6531