The Andromeda Galaxy (our nearest spiral neighbor) has spect?ral lines that show a blue shift. From this we may conclude that:
A) the universe is no longer expanding
B) this particular nearby galaxy is moving toward us
C) this galaxy has merged with the Milky Way and is now part of it
D) this particular nearby galaxy is moving away from us
E) this galaxy has an unusual number of very bright and hot O-type stars in it

Question

Quizplus · Accepted Answer

A blue shift in the spectral lines of the Andromeda Galaxy indicates that it is moving toward us, as the wavelengths of light are compressed (shifted to the blue end of the spectrum) when an object moves closer.

The Andromeda Galaxy (Our Nearest Spiral Neighbor) Has Spect?ral Lines