It’s possible that you’ve seen the Andromeda galaxy (M31) without even realizing it. The massive spiral galaxy appears as a grey, spindle-shaped blob in the night sky, visible with the naked eye in the right conditions. It’s the nearest major galaxy to ours, and astronomers have studied it a lot.
Now astronomers have used the Hubble Space Telescope to map out Andromeda’s enormous halo of hot gas… More about the Andromeda halo in the link below…
https://www.universetoday.com/147618/hubble-shows-the-true-size-of-andromeda/amp/