Which of the following statements is true about a light year?
It is the distance to Alpha Centauri.
It is shorter than the astronomical unit.
It is used to measure long periods of time.
It is used to measure long distances in space.
WILL GIVE BRAINLIST IF CORRECT

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere