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, time and/or keeping:
“There is in him, hidden deep-down, a great instinctive artist, and hence the makings of an aristocrat. In his muddled way, held back by the manacles of his race and time, and his steps made uncertain by a guiding theory which too often eludes his own comprehension, he yet manages to produce works of unquestionable beauty and authority, and to interpret life in a manner that is poignant and illuminating.”
—H.L. (Henry Lewis)
“I am from time to time congratulating myself on my general want of success as a lecturer; apparent want of success, but is it not a real triumph? I do my work clean as I go along, and they will not be likely to want me anywhere again. So there is no danger of my repeating myself, and getting to a barrel of sermons, which you must upset, and begin again with.”
—Henry David Thoreau (1817–1862)
“Bible worship, though at its best it may achieve sublimity by keeping its head in the skies, may also make itself both ridiculous and dangerous by having its feet off the ground.”
—George Bernard Shaw (1856–1950)