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  2. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the retrograde formula its solar day is about 116.8 Earth days, and it has about 1.9 solar days per orbital period.

  3. Solar time - Wikipedia

    en.wikipedia.org/wiki/Solar_time

    On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day). More simply, 1→2 is a complete ...

  4. Synodic day - Wikipedia

    en.wikipedia.org/wiki/Synodic_day

    A synodic day (or synodic rotation period or solar day) is the period for a celestial object to rotate once in relation to the star it is orbiting, and is the basis of solar time. The synodic day is distinguished from the sidereal day, which is one complete rotation in relation to distant stars [1] and is the basis of sidereal time. In the case ...

  5. Rotation period (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Rotation_period_(astronomy)

    Rotation period with respect to distant stars, the sidereal rotation period (compared to Earth's mean Solar days) Synodic rotation period (mean Solar day) Apparent rotational period viewed from Earth Sun [i] 25.379995 days (Carrington rotation) 35 days (high latitude) 25 d 9 h 7 m 11.6 s 35 d ~28 days (equatorial) [2] Mercury: 58.6462 days [3 ...

  6. Solar calendar - Wikipedia

    en.wikipedia.org/wiki/Solar_calendar

    The mean calendar year of such a calendar approximates the sidereal year. Leaping from one lunation to another, but one Sidereal year is the period between two occurrences of the sun, as measured by the stars' solar calendar, which is derived from the Earth's orbit around the sun every 28 years. [3]

  7. Astronomical day - Wikipedia

    en.wikipedia.org/wiki/Astronomical_day

    The exact length has been variously defined as either that of a solar day or of a sidereal day. [1] [2] [3] Astronomical days were historically used by astronomers (in contrast most commonly to solar days), but since the Industrial Revolution this usage has generally fallen out of favor, in order to avoid confusion with more conventional ...

  8. The time when a day on Earth was just 19 hours long - AOL

    www.aol.com/lifestyle/day-earth-used-just-19...

    Known affectionately to scientists as the "boring billion," there was a seemingly endless period in the world's history when the length of a day stayed put. The time when a day on Earth was just ...

  9. Day - Wikipedia

    en.wikipedia.org/wiki/Day

    A sidereal day is about 4 minutes less than a solar day of 24 hours (23 hours 56 minutes and 4.09 seconds), or 0.99726968 of a solar day of 24 hours. [7] There are about 366.2422 stellar days in one mean tropical year (one stellar day more than the number of solar days). [8]