Why does hydrogen, which is abundant in the sun's atmosphere, have relatively weak spectral lines, while calcium, which is not abundant, has very strong spectral lines?

When astronomers look at the spectrum of the Sun, they noticed that the light from one edge is slightly blue-shifted, while light from the opposite age is slightly red-shifted. What does this tell you about the Sun?

Earth tugs the Sun around as it orbits, but it affects the radial velocity of the sun by only 0.09m/s. How large a shift in wavelength does this cause in the Sun's spectrum at 575 nm?

If you observe a star’s blackbody spectrum twice, once from Earth and once from a space shuttle above Earth’s atmosphere, what will you see? An absorption spectrum from Earth and a continuous spectrum from space An absorption spectrum from space and a continuous spectrum from Earth An absorption spectrum from space and an absorption spectrum with more absorption lines from Earth An absorption spectrum from Earth and an absorption spectrum with more absorption lines from space

Explain why the presence of spectral lines of a given element in the solar spectrum tells you that element is present in the sun, but the absence of the lines would not necessarily mean the element is absent from the sun.