Question

how does the speed of the suns rays coming into the atmosphere compare to the speed that they are traveling after having hit the earth, lost momentum, and return to space?
they are traveling faster.
they stay the same speed.
they are more energetic.
they are traveling slower.

Explanation:

The speed of light (sun's rays are electromagnetic radiation, so they travel at the speed of light) in a vacuum (space) or in the atmosphere (which is mostly a vacuum - like environment for light propagation) is constant. When the sun's rays interact with the Earth, the re - emitted radiation (after losing momentum, which relates to energy, not speed for light) still travels at the speed of light. So the speed of the sun's rays coming into the atmosphere and the speed of the re - emitted radiation returning to space stay the same.

Answer:

They stay the same speed.