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  2. Orbital period - Wikipedia

    en.wikipedia.org/wiki/Orbital_period

    This is longer than the sidereal period of its orbit around Earth, which is 27.3 mean solar days, owing to the motion of Earth around the Sun. The draconitic period (also draconic period or nodal period), is the time that elapses between two passages of the object through its ascending node, the point of its orbit where it crosses the ecliptic ...

  3. 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 ...

  4. Elongation (astronomy) - Wikipedia

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

    This diagram shows various possible elongations (ε), each of which is the angular distance between a planet and the Sun from Earth's perspective. In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. [1] The greatest elongation is the maximum angular separation.

  5. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    A mean solar day (what we normally measure as a "day") is the average time between local solar noons ("average" since this varies slightly over a year). Earth makes one rotation around its axis each sidereal day; during that time it moves a short distance (about 1°) along its orbit around the Sun.

  6. Planetary hours - Wikipedia

    en.wikipedia.org/wiki/Planetary_hours

    As each day is divided into 24 hours, the first hour of a day is ruled by the planet three places down in the Chaldean order from the planet ruling the first hour of the preceding day; [2] i.e. a day with its first hour ruled by the Sun ("Sunday") is followed by a day with its first hour ruled by the Moon ("Monday"), followed by Mars ("Tuesday ...

  7. Great conjunction - Wikipedia

    en.wikipedia.org/wiki/Great_conjunction

    in which J and S are the orbital periods of Jupiter (4332.59 days) and Saturn (10759.22 days), respectively. [2] This is about 52 days less than 20 years, but in practice, Earth's orbit size can cause great conjunctions to reoccur anytime between 18 years 10 months and 20 years 8 months after the previous one. (See table below.)

  8. Astronomical transit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_transit

    A simulation of Io transiting Jupiter as seen from the Earth in February 2009. Io's shadow is seen on the surface of Jupiter, leading Io slightly due to the Sun and Earth not being in the same line. One type of transit involves the motion of a planet between a terrestrial observer and the Sun .

  9. Astronomical system of units - Wikipedia

    en.wikipedia.org/wiki/Astronomical_system_of_units

    It is approximately equal to the mean Earth–Sun distance. It was formerly defined as that length for which the Gaussian gravitational constant (k) takes the value 0.017 202 098 95 when the units of measurement are the astronomical units of length, mass and time. [1] The dimensions of k 2 are those of the constant of gravitation (G), i.e., L 3 ...