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The Earth's motion does not determine this value for other planets because an Earth observer is not orbited by the moons in question. For example, Deimos's synodic period is 1.2648 days, 0.18% longer than Deimos's sidereal period of 1.2624 d. [citation needed]
The average distance between Neptune and the Sun is 4.5 billion km (about 30.1 astronomical units (AU), the mean distance from the Earth to the Sun), and it completes an orbit on average every 164.79 years, subject to a variability of around ±0.1 years. The perihelion distance is 29.81 AU, and the aphelion distance is 30.33 AU.
The orbits are ellipses, with foci F 1 and F 2 for Planet 1, and F 1 and F 3 for Planet 2. The Sun is at F 1. The shaded areas A 1 and A 2 are equal, and are swept out in equal times by Planet 1's orbit. The ratio of Planet 1's orbit time to Planet 2's is (/) /.
Orbital mechanics is a core discipline within space-mission design and control. Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity , including both spacecraft and natural astronomical bodies such as star systems , planets , moons , and comets .
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 ).
Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the retrograde formula its solar day is about 116.8 Earth days, and it has about 1.9 solar days per orbital period.
McNaught has a hyperbolic orbit but within the influence of the inner planets, [9] is still bound to the Sun with an orbital period of about 10 5 years. [3] Comet C/1980 E1 has the largest eccentricity of any known hyperbolic comet of solar origin with an eccentricity of 1.057, [ 10 ] and will eventually leave the Solar System.
The sidereal year is 20 min 24.5 s longer than the mean tropical year at J2000.0 (365.242 190 402 ephemeris days). [ 1 ] At present, the rate of axial precession corresponds to a period of 25,772 years, [ 3 ] so sidereal year is longer than tropical year by 1,224.5 seconds (20 min 24.5 s, ~365.24219*86400/25772).