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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 ...
Deimos (/ ˈ d aɪ m ə s /; systematic designation: Mars II) [11] is the smaller and outer of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars. [5] Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos. [12]
It orbits Mars much faster than Mars rotates and completes an orbit in just 7 hours and 39 minutes. As a result, from the surface of Mars it appears to rise in the west, move across the sky in 4 hours and 15 minutes or less, and set in the east, twice each Martian day .
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.
Both sets of findings support an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, [40] similar to the prevailing theory for the origin of Earth's moon. The moons of Mars may have started with a huge collision with a protoplanet one third the mass of Mars that formed a ring around Mars.
Aphelion inside semi-major axis of Mars orbit 3 4 6.405 1.89 189 3 5 6.405 1.45 274 Aphelion inside semi-major axis of Mars orbit 3 5 6.405 1.52 134 Aphelion inside semi-major axis of Mars orbit 4 5 8.54 1.82 88 4 6 8.54 1.53 157 Aphelion inside aphelion of Mars orbit 5 4 10.675 2.49 75 5 5 10.675 2.09 89 5 6 10.675 1.79 111 5 7 10.675 1.54 170
A synchronous orbit around Earth that is circular and lies in the equatorial plane is called a geostationary orbit. The more general case, when the orbit is inclined to Earth's equator or is non-circular is called a geosynchronous orbit. The corresponding terms for synchronous orbits around Mars are areostationary and areosynchronous orbits.
Most centaurs have a prograde orbit around the Sun. The first centaur with a retrograde orbit to be discovered was 20461 Dioretsa. [25] Other known centaurs with retrograde orbits include 2004 NN 8, 2012 TL 139, (434620) 2005 VD, 2006 BZ 8, and 2006 RJ 2. All of these orbits are highly inclined, with inclinations in the range of 160 to 180º. [26]