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Not an astronomer, but I'll give it a shot. If you do the zoom thing, at the highest level? Yes, it's a mush of speckled light -- looks a lot like a noisy or g

Not an astronomer, but I'll give it a shot. If you do the zoom thing, at the highest level? Yes, it's a mush of speckled light -- looks a lot like a noisy or grainy RGB image. But what I think you're seeing are the actual stars -- thousands or maybe ten thousands of them in a full screen at the highest zoom. They're all clumped together because you're looking cross-wise at the galaxy, through the disc. So there so many stars at the highest level of zoom that the image looks grainy.

QuantumRoar 10y ago
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.
- antognini 10y ago
  As a former astronomer, this is correct. Even in extremely high resolution images each pixel contains many, many stars. This fact has actually been used to determine the distances to galaxies. The basic idea is that if the galaxy is nearby, then there will be fewer stars per pixel (say, only a few dozen), but if the galaxy is very far away, there will be many thousands of stars per pixel. As a result, if the galaxy is nearby, there will be a lot of variation in brightness from pixel to pixel because the Poisson fluctuations are proportionally much larger. If the galaxy is more distant, the brightness at each pixel will be more homogenous. This is called the surface brightness fluctuation technique. There's a nice page about it here: https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html

QuantumRoar 10y ago

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.

antognini 10y ago
As a former astronomer, this is correct. Even in extremely high resolution images each pixel contains many, many stars. This fact has actually been used to determine the distances to galaxies. The basic idea is that if the galaxy is nearby, then there will be fewer stars per pixel (say, only a few dozen), but if the galaxy is very far away, there will be many thousands of stars per pixel. As a result, if the galaxy is nearby, there will be a lot of variation in brightness from pixel to pixel because the Poisson fluctuations are proportionally much larger. If the galaxy is more distant, the brightness at each pixel will be more homogenous. This is called the surface brightness fluctuation technique. There's a nice page about it here: https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html