Your guide to astrophotography

M51 (NGC 5194) is a spiral galaxy in the constellation Canes Venatici (Hunting Dogs). In the image, one can see M51 interacting with the dwarf galaxy NGC 5195. The galaxy is fairly close (31 million light years away), which helps make the galaxy appear larger and brighter. Because of this, M51 is a very popular target for astrophotographers.

M51 is in a group of galaxies bound together by gravity. The group called The M51 Group (because M51 is the biggest/brightest of the group) also includes the galaxy M63 – The Sunflower Galaxy.

From our location in the galaxy, the Deer Lick Galaxy Group is close to Stephan's Quintet galaxy group, which I've imaged in a larger mosaic. However, in larger mosaics, some…

A very busy section of the night sky. This image includes two different groups of galaxies: Deer Lick Group (upper-right) and Stephan’s Quintet (lower-left).

First, the big galaxy, NGC 7331, isn’t really part of the group of galaxies behind it. It just appears that way due to its location in the sky. For example, NGC 7331 is around 30 million light years away. But the other galaxies around it (NGC 7333, 7335, 7336, 7337, 7338, 7340) are around 300 million light years away. They are in the background and are not physically grouped with the big galaxy NGC 7331.