Theory of Astronomical Time Keeping
Until recently all the time units that appear natural to us are caused by astronomical phenomena:
- Earth's orbit around the Sun => the year, and the seasons,
- Moon's orbit around the Earth => the month,
- Earth's rotation and the succession of brightness and darkness => the day (and night).
High precision appears problematic:
- amibiguities arise in the exact definition of a rotation or revolution,
- some astronomical processes are uneven and irregular, such as the noncommensurability of year, month, and day,
- there are a multitude of time scales and calendars to solve the first two problems.
Some of these time scales are sidereal time, solar time, and universal time.
Read more about this topic: Theoretical Astronomy
Famous quotes containing the words theory of, theory, time and/or keeping:
“The theory of the Communists may be summed up in the single sentence: Abolition of private property.”
—Karl Marx (1818–1883)
“Could Shakespeare give a theory of Shakespeare?”
—Ralph Waldo Emerson (1803–1882)
“After eight days had passed, it was time to circumcise the child; and he was called Jesus, the name given by the angel before he was conceived in the womb.”
—Bible: New Testament, Luke 2:21.
“Post-structuralism is among other things a kind of theoretical hangover from the failed uprising of ‘68Ma way of keeping the revolution warm at the level of language, blending the euphoric libertarianism of that moment with the stoical melancholia of its aftermath.”
—Terry Eagleton (b. 1943)