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:
“Frankly, these days, without a theory to go with it, I can’t see a painting.”
—Tom Wolfe (b. 1931)
“We New Yorkers see more death and violence than most soldiers do, grow a thick chitin on our backs, grimace like a rat and learn to do a disappearing act. Long ago we outgrew the need to be blowhards about our masculinity; we leave that to the Alaskans and Texans, who have more time for it.”
—Edward Hoagland (b. 1932)
“Well, while I live I’ll fear no other thing
So sore, as keeping safe Nerissa’s ring.”
—William Shakespeare (1564–1616)