I understand how different stars are different colors, and planets, and so-forth. But my thought process assumes the “law of averages” would make most galaxies at least close to the same overall color…..why aren’t they?
In: 42
There’s a few things in play here.
One is general composition. Galaxies can develop a number of different shapes and densities. These conditions can be conducive to developing more larger, blue/white stars, more typical yellow stars, or smaller red stars.
Another is viewing angle. For reasons like those listed above, a galaxy might have a concentration of a certain kind of gas or certain kinds of stars which are more directly visible to us.
Then there’s the weird stuff – red shift and blue shift.
The andromeda galaxy is a galaxy which is moving towards us, and the edge of the galaxy takes on a blue hue because its motion towards us compresses the frequency of the light it emits.
Distant galaxies moving fast away from us appear red because their motion expands the frequency of light as it comes to us.
These are simple explanations of what is a complex phenomenon, but red-shifting galaxies are how we know the universe is expanding.
Latest Answers