A photon escaping FROM a large mass is gravitationally redshifted. What happens to the color of an object falling TOWARD a black hole (observed from far away)?
A) The color of the object will be blueshifted.
B) The color of the object will remain unchanged.
C) The color of the object will be redshifted because the photons reaching distant observers are escaping the vicinity of the black hole.
D) As the object accelerates toward the black hole, moving faster and faster, the idea of color ceases to have meaning as the photons shift from visible violet to ultraviolet and then X-rays and gamma rays.

Question

Quizplus · Accepted Answer

The photons emitted by the object falling toward the black hole are redshifted as they climb out of the gravitational well, similar to the gravitational redshift experienced by photons escaping a large mass.

A Photon Escaping FROM a Large Mass Is Gravitationally Redshifted