As a somewhat astronomer, this explanation seems reasonable. Usually you can't discern individual stars in another galaxy, like in the center of the Andromeda

As a somewhat astronomer, this explanation seems reasonable. Usually you can't discern individual stars in another galaxy, like in the center of the Andromeda galaxy (But doing statistics is still possible). However, the Andromeda galaxy seems close enough that at the outer edge of it, you can isolate them to do astronomy on individual stars (like spectroscopy). Edit: Also, you can find stars in almost all colors. The average of the colors depends on the age of the stars in the galaxy. If there are only a few new stars born, the galaxy will appear redder. If there are many new stars born, it appears bluer (see Hertzsprung-Russel diagram). The way the stars appear in different colors means that they have different ages and masses. Noise in a telescope (except for high energy particles hitting your detector) is thermal noise. It will only appear if there's almost no light detected. So if it were noise, it should be the other way round: Noisy where there are little stars and no noise where there are a lot of stars. If you'd ask me, I'd say there's exactly zero visible noise in there.