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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 South celestial pole is correspondingly found at 9 h 10 m 42 s and −52° 53.0′, which is a couple of degrees from the 2.5-magnitude star Kappa Velorum (which is at 9 h 22 m 06.85 s −55° 00.6′), which could therefore be considered the southern polar star.
At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. [188] Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years. [189] Mars has its closest approach to Earth in a synodic period of 779.94 days.
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.
Initially, the InSight mission, the first to study the interior of Mars, was supposed to last about two years after it landed in November 2018. But NASA extended the mission for another two years.
The Red Planet's spin is speeding up a hair fast enough to shorten the length of a Martian day by a fraction of a millisecond per year. NASA's Mars Insight lander died a few months ago, no longer ...
The corresponding values for Earth are currently 23 h 56 m 4.0916 s and 24 h 00 m 00.002 s, respectively, which yields a conversion factor of 1.027 491 2517 Earth days/sol: thus, Mars's solar day is only about 2.75% longer than Earth's; approximately 73 sols pass for every 75 Earth days.
The most common and best-known class is the trojan, which librates around one of the two stable Lagrangian points (Trojan points), L 4 and L 5, 60° ahead of and behind the larger body respectively. Another class is the horseshoe orbit , in which objects librate around 180° from the larger body.