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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.
If a planet rotates prograde, and the sidereal day exactly equals the orbital period, then the formula above gives an infinitely long solar day (division by zero). This is the case for a planet in synchronous rotation ; in the case of zero eccentricity, one hemisphere experiences eternal day, the other eternal night, with a "twilight belt ...
(7 months, 1 day) Mars 7's lander was released prematurely and missed Mars. [89] Mariner 10: Venus 3 November 1973 5 February 1974 95 days (3 months, 3 days) Mariner 10 flew by Venus at a minimum distance of 5768 km. It was the first use of a gravity assist by an interplanetary spacecraft. [90] Mercury 29 March 1974 147 days (4 months, 27 days)
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]
In April 2014, the first measurement of a planet's rotation period was announced: the length of day for the super-Jupiter gas giant Beta Pictoris b is 8 hours (based on the assumption that the axial tilt of the planet is small.) [27] [28] [29] With an equatorial rotational velocity of 25 km per second, this is faster than for the giant planets ...
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
Voyager 1 and the other probes that are in or on their way to interstellar space, except New Horizons. Voyager 1 transmitted audio signals generated by plasma waves from interstellar space On September 12, 2013, NASA officially confirmed that Voyager 1 had reached the interstellar medium in August 2012 as previously observed.