Question

A star has a spectrum shift exhibiting a blue shift. What can you conclude about the distance from Earth to that star?

The distance is increasing.

The distance is decreasing.

The distance will remain unchanged.

The distance varies with the temperature of the star.

Answer 1

This problem concerns the doppler effect. If the distance was decreasing, as in B, the star would appear red. The distance between stars is always changing, so C would not be the answer. The answer isn't D because there isn't really any correlation between distance and temperature. The answer is A. As the universe expands, all stars move farther away from each other. All stars actually exhibit at least a little bit of blue shift.