<P> Solar midnight is the time opposite to solar noon, when the Sun is closest to the nadir, and the night is equidistant from dusk and dawn . Due to the advent of time zones, which regularize time across a range of meridians, and daylight saving time, it rarely coincides with 12 midnight on the clock . Solar midnight depends on longitude and time of the year rather than on time zone . </P> <P> In the Northern Hemisphere, "midnight" had an ancient geographic association with "north" (as did "noon" with "south"--see noon). Modern Polish, Belarusian, Ukrainian and Serbian preserve this association with its word for "midnight" (północ, поўнач, північ, пoнoħ--literally "half - night"), which also means "north". </P> <P> Midnight marks the beginning and ending of each day in civil time throughout the world . As the dividing point between one day and another, midnight defies easy classification as either part of the preceding day or of the following day . Though there is no global unanimity on the issue, most often midnight is considered the start of a new day and is associated with the hour 00: 00 . Even in locales with this technical resolution, however, vernacular references to midnight as the end of any given day may be common . </P> <P> Strictly speaking, it is incorrect to use "a.m." and "p.m." when referring to noon or midnight . The abbreviation a.m. stands for ante meridiem or before noon, and p.m. stands for post meridiem or after noon . Since noon is neither before nor after noon, and midnight is exactly twelve hours before and after noon, neither abbreviation is correct . However, many digital representations of time are configured to require an "a.m." or "p.m." designation, preventing the correct absence of such designators at midnight . In such cases, there is no international standard defining which arbitrary selection is best . </P>

Is 12am the start or end of the day