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  2. Retrograde and prograde motion - Wikipedia

    en.wikipedia.org/wiki/Retrograde_and_prograde_motion

    Most of the material orbits and rotates in one direction. This uniformity of motion is due to the collapse of a gas cloud. [1] The nature of the collapse is explained by conservation of angular momentum. In 2010 the discovery of several hot Jupiters with backward orbits called into question the theories about the formation of planetary systems. [2]

  3. Apparent retrograde motion - Wikipedia

    en.wikipedia.org/wiki/Apparent_retrograde_motion

    This means that the Earth completes one sidereal rotation before the Moon is able to complete one orbit. As a result, it looks like the Moon is travelling in the opposite direction, otherwise known as apparent retrograde motion. A person standing on Earth "catches up" to the Moon and passes it because the Earth completes one rotation before the ...

  4. Earth's rotation - Wikipedia

    en.wikipedia.org/wiki/Earth's_rotation

    Earth's rotation axis moves with respect to the fixed stars (inertial space); the components of this motion are precession and nutation. It also moves with respect to Earth's crust; this is called polar motion. Precession is a rotation of Earth's rotation axis, caused primarily by external torques from the gravity of the Sun, Moon and other bodies.

  5. Astronomy on Mars - Wikipedia

    en.wikipedia.org/wiki/Astronomy_on_Mars

    The maximum angular separation of the Earth and Moon varies considerably according to the relative distance between the Earth and Mars: it is about 25′ when Earth is closest to Mars (near inferior conjunction) but only about 3.5′ when the Earth is farthest from Mars (near superior conjunction). For comparison, the apparent diameter of the ...

  6. Orbit of Mars - Wikipedia

    en.wikipedia.org/wiki/Orbit_of_Mars

    Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...

  7. Earth’s core might be reversing its spin. It ‘won’t affect ...

    www.aol.com/news/earth-core-might-reversing-spin...

    “We infer the inner core rotation changes direction every 35 years,” Dr. Song told McClatchy News. ... Earth’s inner core, a red-hot ball of iron 1,800 miles below our feet, stopped spinning ...

  8. Deferent and epicycle - Wikipedia

    en.wikipedia.org/wiki/Deferent_and_epicycle

    The Tychonic model was a hybrid model that blended the geocentric and heliocentric characteristics, with a still Earth that has the sun and moon surrounding it, and the planets orbiting the Sun. To Brahe, the idea of a revolving and moving Earth was impossible, and the scripture should be always paramount and respected. [33]

  9. Synchronous orbit - Wikipedia

    en.wikipedia.org/wiki/Synchronous_orbit

    A synchronous orbit around Earth that is circular and lies in the equatorial plane is called a geostationary orbit. The more general case, when the orbit is inclined to Earth's equator or is non-circular is called a geosynchronous orbit. The corresponding terms for synchronous orbits around Mars are areostationary and areosynchronous orbits.