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William W
Lv 6
William W asked in Science & MathematicsAstronomy & Space · 1 decade ago

Sidereal day length & number?

What is the length of a sidereal day and how many are there in a year?

3 Answers

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  • Morningfox
    Lv 7
    1 decade ago
    Favorite Answer

    The sidereal day is 23 hours, 56 minutes, and 4.098 seconds, plus or minus several milliseconds. (This is not a constant value. Wiki gives the value 23h 56m 4.090530833s for back in June of 2000, I give the value for right now.)

    There are various kinds of year. The average calendar year is 365.2425 days of 24 hours each (plus sometimes an extra leap second.) That means there are 366.242470 sidereal days in an average year (plus or minus 0.000043 days).

    Source(s): http://en.wikipedia.org/wiki/Sidereal_day http://www.iers.org/MainDisp.csl?pid=95-97
  • bikenbeer2000
    Lv 7
    1 decade ago

    The length of a sidereal day is 23 hours 56 minutes 4.091 seconds. There are 366.24219 of them in a Tropical Year (the mean time for the Sun to return to the equinox).

  • Charles
    Lv 6
    1 decade ago

    This is one of those questions for which wikipedia is quite valuable.

    http://en.wikipedia.org/wiki/Sidereal_day

    HTH

    Charles

    Source(s): http://en.wikipedia.org/wiki/Sidereal_day
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