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

Other articles related to "theory of astronomical time keeping, time":

Theoretical Astronomy - Theory of Astronomical Time Keeping - Stellar Dynamical Time Scale
... For a star, the dynamical time scale is defined as the time that would be taken for a test particle released at the surface to fall under the star's potential to ... In other words, the dynamical time scale measures the amount of time it would take a certain star to collapse in the absence of any internal pressure ... As an example, the Sun dynamical time scale is approximately 1133 seconds ...

Famous quotes containing the words theory of, keeping, time and/or theory:

    We commonly say that the rich man can speak the truth, can afford honesty, can afford independence of opinion and action;—and that is the theory of nobility. But it is the rich man in a true sense, that is to say, not the man of large income and large expenditure, but solely the man whose outlay is less than his income and is steadily kept so.
    Ralph Waldo Emerson (1803–1882)

    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)

    Gustav Aschenbach was the writer who spoke for all those who work on the brink of exhaustion, who labor and are heavy-laden, who are worn out already but still stand upright, all those moralists of achievement who are slight of stature and scanty of resources, but who yet, by some ecstasy of the will and by wise husbandry, manage at least for a time to force their work into a semblance of greatness.
    Thomas Mann (1875–1955)

    ... liberal intellectuals ... tend to have a classical theory of politics, in which the state has a monopoly of power; hoping that those in positions of authority may prove to be enlightened men, wielding power justly, they are natural, if cautious, allies of the “establishment.”
    Susan Sontag (b. 1933)