Messier 51

M51 is a pair of interacting galaxies, NGC 5194 and NGC 5195, their last close approach was about 400 million years ago. They are now 500,000 light years apart with the smaller NGC5195 behind the larger galaxy. That last closest approach caused an enormous amount of star formation in the larger galaxy. We can see this happening in the spiral arms as blue and pink blobs. The close approach also stripped stars out of the galaxies and we see them as a glow of streamers emitted from the galaxies.

The galaxy was first seen by Charles Messier in 1773, although he only saw the brighter of the two galaxies, it wasn’t until 1781 when Pierre Méchain observed the companion galaxy. It wasn’t until the 19th before the spiral structure of the galaxy was discovered by the 3rd Earl of Rosse in Ireland using his 72” telescope known as the Leviathan of Parsonstown in 1848. The first photograph of M51 was taken in 1889.

There have been four recent supernovae in M51, 1945, 1994, 2005 and 2011. So it’s one worth keeping an eye on.

This image was taken over 13 nights through April and May 2025, with the SeeStar S50. A total exposure of 25h 10m 20s made from 20 and 30” subs, processed with PixInsight