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:
“In the theory of gender I began from zero. There is no masculine power or privilege I did not covet. But slowly, step by step, decade by decade, I was forced to acknowledge that even a woman of abnormal will cannot escape her hormonal identity.”
—Camille Paglia (b. 1947)
“It makes no sense to say what the objects of a theory are,
beyond saying how to interpret or reinterpret that theory in another.”
—Willard Van Orman Quine (b. 1908)
“The time to enjoy a European tour is about three weeks after you unpack.”
—George Ade (1866–1944)
“BOSWELL “ ... Is not the fear of death natural to man?” JOHNSON. “So much so, Sir, that the whole of life is but keeping away the thought of it.””
—Samuel Johnson (1709–1784)