When geologists refer to the "big five," what are they referring to?
the five most important organisms that have become extinct.
the five largest mass extinctions in earth's history.
the five most influential events that have changed the surface of the earth.
the five most important inventions that have allowed scientists to study mass extinctions.

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

hope this ! this is not copied! search it up, it's free of plagiarism!