Question

the subtle changes in the color of a starlight that let astronomers find planets, measure the speeds of galaxies, and track the expansion of the universe is called?
doppler shift
red shift
star shift
galaxy shift
when stars are moving towards us, they appear to be more of what color?
green
red
blue
black
the beginning expansion of the big bang happened relatively slowly compared to how it is expanding now.
true
false

Explanation:

• First question: The Doppler Shift is a phenomenon where there are changes in the frequency (and thus color - related to frequency for light) of a wave (like starlight) due to the relative motion between the source (star) and the observer. Red Shift is a type of Doppler Shift where light is shifted towards the red end (longer wavelength) when the source is moving away. Star Shift and Galaxy Shift are not standard scientific terms in this context.
• Second question: When a star is moving towards us, according to the Doppler effect for light, the wavelength of the light is compressed. Shorter wavelengths correspond to the blue - end of the visible spectrum (blue light has a shorter wavelength than red light).
• Third question: The Big Bang expansion was extremely rapid at the beginning (the initial inflationary period was a very fast expansion), and currently, while the universe is still expanding, the rate was much higher at the start.

Answer:

1. Doppler Shift
2. Blue
3. False