What does a galaxy's redshift indicate about its motion?
A. The galaxy is moving closer to us.
B. The galaxy is moving away from us.
C. The galaxy is not moving at all.
D. The galaxy is spinning faster.
What is the primary cause of redshift in light from distant galaxies?
A. The light is absorbed by gas and dust.
B. The light waves are compressed by nearby stars.
C. The light is scattered by cosmic radiation.
D. The light waves are stretched as the universe expands.
Which of the following describes blueshift?
A. Light waves from a galaxy are stretched.
B. A galaxy is moving in a circular orbit.
C. Light waves from a galaxy are compressed.
D. A galaxy has stopped moving entirely.