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  2. Orbit of Mars - Wikipedia

    en.wikipedia.org/wiki/Orbit_of_Mars

    Extra-close oppositions of Mars happen every 15 to 17 years, when we pass between Mars and the Sun around the time of its perihelion (closest point to the Sun in orbit). The minimum distance between Earth and Mars has been declining over the years, and in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost ...

  3. Astronomy on Mars - Wikipedia

    en.wikipedia.org/wiki/Astronomy_on_Mars

    Mars has an axial tilt of 25.19°, quite close to the value of 23.44° for Earth, and thus Mars has seasons of spring, summer, autumn, winter as Earth does. As on Earth, the southern and northern hemispheres have summer and winter at opposing times. However, the orbit of Mars has significantly greater eccentricity than that of Earth. Therefore ...

  4. Areostationary orbit - Wikipedia

    en.wikipedia.org/wiki/Areostationary_orbit

    An areostationary orbit, areosynchronous equatorial orbit (AEO), or Mars geostationary orbit is a circular areo­synchronous orbit (ASO) approximately 17,032 km (10,583 mi) in altitude above the Mars equator and following the direction of Mars's rotation. An object in such an orbit has an orbital period equal to Mars's rotational period, and so ...

  5. Galaxy rotation curve - Wikipedia

    en.wikipedia.org/wiki/Galaxy_rotation_curve

    A companion paper by Maarten Schmidt showed that this rotation curve could be fit by a flattened mass distribution more extensive than the light. [9] In 1959, Louise Volders used the same telescope to demonstrate that the spiral galaxy M33 also does not spin as expected according to Keplerian dynamics. [10]

  6. Exoplanet orbital and physical parameters - Wikipedia

    en.wikipedia.org/wiki/Exoplanet_orbital_and...

    Nodal precession is rotation of a planet's orbital plane. Nodal precession is more easily seen as distinct from periastron precession when the orbital plane is inclined to the star's rotation, the extreme case being a polar orbit. WASP-33 is a fast-rotating star that hosts a hot Jupiter in an almost polar orbit.

  7. Vicarious Hypothesis - Wikipedia

    en.wikipedia.org/wiki/Vicarious_Hypothesis

    [1] [2] [3] The hypothesis adopted the circular orbit and equant of Ptolemy's planetary model as well as the heliocentrism of the Copernican model. [4] [5] Calculations using the Vicarious Hypothesis did not support a circular orbit for Mars, leading Kepler to propose elliptical orbits as one of three laws of planetary motion in Astronomia Nova ...

  8. Orbital speed - Wikipedia

    en.wikipedia.org/wiki/Orbital_speed

    In gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter (the combined center of mass) or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.

  9. Newton's theorem of revolving orbits - Wikipedia

    en.wikipedia.org/wiki/Newton's_theorem_of...

    If the particle requires a time T to move from one apse to the other, this implies that, in the same time, the long axis will rotate by an angle β = ΩT = (k − 1)ωT = (k − 1)×180°. For an inverse-square law such as Newton's law of universal gravitation , where n equals 1, there is no angular scaling ( k = 1), the apsidal angle α is 180 ...