It's really big in the sky, much larger than the moon from earth.
It's a very low light image and your not seeing all of it as our unaided human eye is not capable.
The picture above shows the crescent Moon in the sky, and superposed near it is the Andromeda galaxy, the nearest big spiral to our own Milky Way. This is approximately how big the Andromeda galaxy would actually look in our sky if it were brighter or our eyes were more sensitive to extreme low light.