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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). The other type of commonly used "rotation period" is the object's synodic rotation period (or solar day), which may differ, by a fraction ...
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]
It is approximately 24 hours, 39 minutes, 35 seconds long. A Martian year is approximately 668.6 sols, equivalent to approximately 687 Earth days [1] or 1.88 Earth years. The sol was adopted in 1976 during the Viking Lander missions and is a measure of time mainly used by NASA when, for example, scheduling the use of a Mars rover. [2] [3]
With the exoplanet sample known in 2009, a group of astronomers estimated that "(1) around 35% of the published eccentric one-planet solutions are statistically indistinguishable from planetary systems in 2:1 orbital resonance, (2) another 40% cannot be statistically distinguished from a circular orbital solution" and "(3) planets with masses ...
The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. [49] Uranus was shown to have a magnetic field that was misaligned with its rotational axis, unlike other planets that had been visited to that point, [50] [53] and a helix-shaped magnetic tail stretching 10 million kilometers (6 million miles) away from the Sun. [50]
A synodic day (or synodic rotation period or solar day) is the period for a celestial object to rotate once in relation to the star it is orbiting, and is the basis of solar time. The synodic day is distinguished from the sidereal day , which is one complete rotation in relation to distant stars [ 1 ] and is the basis of sidereal time.
Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin [4] [5] based on its characteristics; also known by its Kepler object of interest designation KOI-7016.01) is a candidate [6] [7] super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope.
(1 yr, 2 mo, 20 d) Vega 1 flew by Halley at a minimum distance of 8,890 km. Vega 2: Venus 21 December 1984 15 June 1985 177 days (5 months, 26 days) Vega 2 flew by Venus. [99] Comet 1P/Halley: 9 March 1986 444 days (1 yr, 2 mo, 17 d) Vega 2 flew by Halley at a minimum distance of 8,890 km. Sakigake: Comet 1P/Halley: 7 January 1985 11 March 1986 ...