- published: 08 Dec 2010
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Midnight is the transition time period from one day to the next: the moment when the date changes. In the Roman time system, midnight was halfway between sunset and sunrise, varying according to the seasons.
Solar midnight is that time opposite of solar noon, when the sun is closest to nadir and the night is equidistant from dusk and dawn. Due to the advent of time zones, which make time identical across a range of meridians, and daylight saving time, it rarely coincides with midnight on a clock. Solar midnight is dependent on longitude and time of the year rather than on a time zone.
In the northern hemisphere, "midnight" had an ancient geographic association with "north" (as did "noon" with "south" – see noon). Modern Polish and Ukrainian preserve this association with their words for "midnight" ("północ", "північ" – literally "half-night"), which also means "north".
Midnight marks the beginning and ending of each day in civil time throughout the world. It is the dividing point between one day and another. With 12-hour time notation, most authorities recommend avoiding confusion between noon and midnight by using "midnight", "12 midnight", or "12:00 midnight."
Autumn or fall (/ˈɔːtəm/ AW-təm or /fɔːl/ fawl, respectively) is one of the four temperate seasons. Autumn marks the transition from summer into winter, in September (Northern Hemisphere) or March (Southern Hemisphere) when the arrival of night becomes noticeably earlier.
The equinoxes might be expected to be in the middle of their respective seasons, but temperature lag (caused by the thermal latency of the ground and sea) means that seasons appear later than dates calculated from a purely astronomical perspective. The actual lag varies with region. Some cultures regard the autumnal equinox as "mid-autumn", others with a longer lag treat it as the start of autumn. Meteorologists (and most of the temperate countries in the southern hemisphere) use a definition based on months, with autumn being September, October and November in the northern hemisphere, and March, April and May in the southern hemisphere.
In North America, autumn is usually considered to start with the September equinox. In traditional East Asian solar term, autumn starts on or around 8 August and ends on about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October and November. However, according to the Irish Calendar which is based on ancient Gaelic traditions, autumn lasts throughout the months of August, September, and October, or possibly a few days later, depending on tradition. In Australia, autumn officially begins on March 1 and ends May 31 According to United States tradition, autumn runs from the day after Labor Day (i.e. the Tuesday following the first Monday of September) through Thanksgiving (i.e. the fourth Thursday in November), after which the holiday season that demarcates the unofficial beginning of winter begins.