The most readily observed motion of a celestial object is produced by

Arock collection comes from which part of earth?

While standing outdoors one evening, you are exposed to the following four types of electromagnetic radiation: yellow light from a sodium street lamp, radio waves from an am radio station, radio waves from an fm radio station, and microwaves from an antenna of a communications system. rank these type of waves in terms of increasing photon energy.

Could we see a galaxy that is 20 billion light-years away?