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Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...
The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size. [190] At their furthest Mars and Earth can be as far as 401 million km (249 million mi) apart. [ 191 ]
Substituting the mass of Mars for M and the Martian sidereal day for T and solving for the semimajor axis yields a synchronous orbit radius of 20,428 km (12,693 mi) above the surface of the Mars equator. [3] [4] [5] Subtracting Mars's radius gives an orbital altitude of 17,032 km (10,583 mi). Two stable longitudes exist - 17.92°W and 167.83°E.
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]
In most situations it is impractical to achieve escape velocity almost instantly, because of the acceleration implied, and also because if there is an atmosphere, the hypersonic speeds involved (on Earth a speed of 11.2 km/s, or 40,320 km/h) would cause most objects to burn up due to aerodynamic heating or be torn apart by atmospheric drag. For ...
Launching a rover into space and landing it safely on an alien surface is difficult enough. Then you have to get the thing to actually drive.Humans put seven rovers on the moon and six on Mars ...
The sixteen equatorial quadrangles are the smallest, with surface areas of 4,500,000 square kilometres (1,700,000 sq mi) each, while the twelve mid-latitude quadrangles each cover 4,900,000 square kilometres (1,900,000 sq mi). The two polar quadrangles are the largest, with surface areas of 6,800,000 square kilometres (2,600,000 sq mi) each.
This list contains a selection of objects 50 and 99 km in radius (100 km to 199 km in average diameter). The listed objects currently include most objects in the asteroid belt and moons of the giant planets in this size range, but many newly discovered objects in the outer Solar System are missing, such as those included in the following ...