This is a very basic question, but I am a little confused. As far as I know, the temperature of a star is analyzed based on the color of the light it emits. So, if a star is moving away from us, then ...
What are the most extreme temperatures (both hot and cold) stars have been detected at? Is there an upper and lower limit for the detected temperature of stars?
Are there any known correlations between the changes in planetary surface temperatures in a solar system? If so, do the farthest planets have smaller albeit correlated changes?