A star is moving toward Earth at 90% the speed of light. The star emits light, which moves away from the star at the speed of light. What do Earth-based astronomers measure for the speed of this
Light?
A) 1.2c
B) 0.98c
C) c
D) 0.95c
E) 1.9c

Question

Quizplus · Accepted Answer

According to the theory of relativity, the speed of light in a vacuum is always constant and does not depend on the speed of the source or the observer. Therefore, regardless of the star's motion towards Earth, the speed of light measured by Earth-based astronomers remains c (the speed of light in a vacuum, approximately 299,792 kilometers per second).

A Star Is Moving Toward Earth at 90% the Speed