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  2. Mars - Wikipedia

    en.wikipedia.org/wiki/Mars

    The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between successive oppositions can range from 764 to 812. [189] The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable ...

  3. Orbit of Mars - Wikipedia

    en.wikipedia.org/wiki/Orbit_of_Mars

    Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million km) (12.673 light minutes), and an eccentricity of 0.0934. [1][2] The planet orbits the Sun in 687 days [3] and travels 9.55 AU in doing so, [4] making the average orbital speed 24 km/s. The eccentricity is greater than that of every other planet except Mercury ...

  4. Geostationary orbit - Wikipedia

    en.wikipedia.org/wiki/Geostationary_orbit

    A geostationary orbit, also referred to as a geosynchronous equatorial orbit[a] (GEO), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's ...

  5. Comoving and proper distances - Wikipedia

    en.wikipedia.org/wiki/Comoving_and_proper_distances

    Comoving distance and proper distance. Comoving distance is the distance between two points measured along a path defined at the present cosmological time. For objects moving with the Hubble flow, it is deemed to remain constant in time. The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following ...

  6. Lunar distance - Wikipedia

    en.wikipedia.org/wiki/Lunar_distance

    The lunar distance is on average approximately 385,000 km (239,000 mi), or 1.28 light-seconds; this is roughly 30 times Earth's diameter or 9.5 times Earth's circumference. Around 389 lunar distances make up an AU astronomical unit (roughly the distance from Earth to the Sun). Lunar distance is commonly used to express the distance to near ...

  7. Geology of Mars - Wikipedia

    en.wikipedia.org/wiki/Geology_of_Mars

    For example, the peak discharge required to carve the 28-km-wide Ares Vallis is estimated to have been 14 million cubic metres (500 million cu ft) per second, over ten thousand times the average discharge of the Mississippi River. [41] Mars Orbital Laser Altimeter (MOLA) derived image of Planum Boreum. Vertical exaggeration is extreme.

  8. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    v. t. e. The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).

  9. Kepler's laws of planetary motion - Wikipedia

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

    t. e. In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler absent the third law in 1609 and fully in 1619, describe the orbits of planets around the Sun. These laws replaced circular orbits and epicycles in the heliocentric theory of Nicolaus Copernicus with elliptical orbits and explained how planetary velocities vary.