The terms "a.m." and "p.m." (as in see you at the movies at 8:30 p.m.) derive from what astronomical idea?
A) the Sun passes through the meridian in roughly the middle of the day
B) the Moon's phases change on a monthly cycle, getting fuller and then getting smaller
C) The apparent solar time differs from the mean solar time by a much greater amount in the first half of the day than the second half
D) The seasons in the northern hemisphere are backward from the seasons in the southern hemisphere
E) Putting the prime meridian in Greenwich, England required the approval of the prime minister. We think of time measurements as being either before or after that approval.
Section 4.4: The Calendar

Question

Quizplus · Accepted Answer

The terms "a.m." (ante meridiem) and "p.m." (post meridiem) refer to the times before and after the Sun passes through the local meridian, which is roughly the middle of the day. This is directly related to the apparent motion of the Sun across the sky.

The Terms "A