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 truth is a series of truisms.”
—J.L. (John Langshaw)
“If my theory of relativity is proven correct, Germany will claim me as a German and France will declare that I am a citizen of the world. Should my theory prove untrue, France will say that I am a German and Germany will declare that I am a Jew.”
—Albert Einstein (1879–1955)
“There is a time when even justice brings harm.”
—Sophocles (497–406/5 B.C.)
“On the whole, yes, I would rather be the Chief Justice of the United States, and a quieter life than that which becomes at the White House is more in keeping with the temperament, but when taken into consideration that I go into history as President, and my children and my children’s children are the better placed on account of that fact, I am inclined to think that to be President well compensates one for all the trials and criticisms he has to bear and undergo.”
—William Howard Taft (1857–1930)