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:
“Thus the theory of description matters most.
It is the theory of the word for those
For whom the word is the making of the world,
The buzzing world and lisping firmament.”
—Wallace Stevens (1879–1955)
“[Anarchism] is the philosophy of the sovereignty of the individual. It is the theory of social harmony. It is the great, surging, living truth that is reconstructing the world, and that will usher in the Dawn.”
—Emma Goldman (1869–1940)
“For of those [cities] that were great in earlier times, most of them have now become small, while those which were great in my time were small formerly.”
—Herodotus (c. 484–424 B.C.)
“Let us shun self-analyzation, self-consciousness, morbidness, affectation, attitudinizing. Let us look ahead as little as possible, keeping our eyes on our brushes and on the world of beauty around us.”
—Mariana Griswold Van Rensselaer (1851–1934)