Theoretical Astronomy - Theory of Astronomical Time Keeping

Theory of Astronomical Time Keeping

Until recently all the time units that appear natural to us are caused by astronomical phenomena:

  1. Earth's orbit around the Sun => the year, and the seasons,
  2. Moon's orbit around the Earth => the month,
  3. Earth's rotation and the succession of brightness and darkness => the day (and night).

High precision appears problematic:

  1. amibiguities arise in the exact definition of a rotation or revolution,
  2. some astronomical processes are uneven and irregular, such as the noncommensurability of year, month, and day,
  3. 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 rights enables us to rise and overthrow obstacles, but not to found a strong and lasting accord between all the elements which compose the nation.
    Giuseppe Mazzini (1805–1872)

    The theory [before the twentieth century] ... was that all the jobs in the world belonged by right to men, and that only men were by nature entitled to wages. If a woman earned money, outside domestic service, it was because some misfortune had deprived her of masculine protection.
    Rheta Childe Dorr (1866–1948)

    I didn’t have to think up so much as a comma or a semicolon; it was all given, straight from the celestial recording room. Weary, I would beg for a break, an intermission, time enough, let’s say, to go to the toilet or take a breath of fresh air on the balcony. Nothing doing!
    Henry Miller (1891–1980)

    By recognizing a favorable opinion of yourself, and taking pleasure in it, you in a measure give yourself and your peace of mind into the keeping of another, of whose attitude you can never be certain. You have a new source of doubt and apprehension.
    Charles Horton Cooley (1864–1929)