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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 ...
It has 24 months to accommodate the longer Martian year while keeping the notion of a "month" that is reasonably similar to the length of an Earth month. On Mars, a "month" would have no relation to the orbital period of any moon of Mars, since Phobos and Deimos orbit in about 7 hours and 30 hours
On both Earth and Mars, these two precessions are in opposite directions, and therefore add, to make the precession cycle between the tropical and anomalistic years 21,000 years on Earth and 29,700 Martian years (55,900 Earth years) on Mars. As on Earth, the period of rotation of Mars (the length of its day) is slowing down.
In this frame of reference, Earth's rotation is close to constant, but the stars appear to rotate slowly with a period of about 25,800 years. It is also in this frame of reference that the tropical year (or solar year), the year related to Earth's seasons, represents one orbit of Earth around the Sun. The precise definition of a sidereal day is ...
The Clancy Mars year is reckoned from one Martian northward equinox to the next (L s = 0°), and specific dates within a given year are expressed in L s. The Clancy Mars year count is approximately equal to the Darian year count minus 183. The Allison Mars sol date epoch equates to L s = 276.6° in a year that is undefined in the Clancy Mars ...
The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. [2] As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day, the orientation of the north pole of Mars is close to the star Deneb. [21]
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.
Several factors make placing a spacecraft into an areostationary orbit more difficult than a geostationary orbit. Since the areostationary orbit lies between Mars's two natural satellites, Phobos (semi-major axis: 9,376 km) and Deimos (semi-major axis: 23,463 km), any satellites in the orbit will suffer increased orbital station keeping costs due to unwanted orbital resonance effects.