Astronomers Studying the Light from Calcium Atoms Located in a Galaxy

Multiple Choice

Astronomers studying the light from calcium atoms located in a galaxy in the constellation Boötes find that the spectral lines are shifted toward the red end of the spectrum. The redshift indicates that the galaxy is moving away at a speed of 3.9 × 10⁶ m/s. What is the distance (in light . years) to the galaxy?

A) 4.7 × 10⁹ light . years
B) 2.3 × 10⁸ light .years
C) 1.1 × 10⁷ light . years
D) 8.4 × 10⁶ light . years
E) 6.6 × 10⁴ light . years