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  2. Timeline of Solar System astronomy - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_Solar_System...

    1619 – Johannes Kepler states his third empirical law of planetary motion, which relates the distance and period of the planetary orbits. [84] 1631 – Pierre Gassendi is the first to observe the transit of Mercury. He was surprised by the small size of the planet compared to the Sun. [85]

  3. Solar rotation - Wikipedia

    en.wikipedia.org/wiki/Solar_rotation

    At the equator, the solar rotation period is 24.47 days. This is called the sidereal rotation period, and should not be confused with the synodic rotation period of 26.24 days, which is the time for a fixed feature on the Sun to rotate to the same apparent position as viewed from Earth (the Earth's orbital rotation is in the same direction as the Sun's rotation).

  4. Orbital period - Wikipedia

    en.wikipedia.org/wiki/Orbital_period

    The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy , it usually applies to planets or asteroids orbiting the Sun , moons orbiting planets, exoplanets orbiting other stars , or binary stars .

  5. Timeline of astronomy - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_astronomy

    The Hindu cosmological time cycles explained in the Surya Siddhanta, give the average length of the sidereal year (the length of the Earth's revolution around the Sun) as 365.2563627 days, which is only 1.4 seconds longer than the modern value of 365.256363004 days. [10]

  6. Timeline of discovery of Solar System planets and their moons

    en.wikipedia.org/wiki/Timeline_of_discovery_of...

    The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...

  7. Rotation period (astronomy) - Wikipedia

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

    In astronomy, the rotation period or spin period [1] of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the sidereal rotation period (or sidereal day), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars (inertial space).

  8. Six planets are aligning this month. Here's the best time to ...

    www.aol.com/news/six-planets-aligning-month...

    Six planets will be in alignment during the planet parade: Mars, Jupiter, Uranus, Neptune, Venus, and Saturn. Uranus and Neptune won't appear as "bright planets," so you'll need a telescope or ...

  9. Kepler's laws of planetary motion - Wikipedia

    en.wikipedia.org/wiki/Kepler's_laws_of_planetary...

    Planet orbiting the Sun in a circular orbit (e=0.0) Planet orbiting the Sun in an orbit with e=0.5 Planet orbiting the Sun in an orbit with e=0.2 Planet orbiting the Sun in an orbit with e=0.8 The red ray rotates at a constant angular velocity and with the same orbital time period as the planet, =.