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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 ...
The apsides refer to the farthest (2) and nearest (3) points reached by an orbiting planetary body (2 and 3) with respect to a primary, or host, body (1). An apsis (from Ancient Greek ἁψίς (hapsís) 'arch, vault'; pl. apsides / ˈ æ p s ɪ ˌ d iː z / AP-sih-deez) [1] [2] is the farthest or nearest point in the orbit of a planetary body about its primary body.
Log-log plot of period T vs semi-major axis a (average of aphelion and perihelion) ... Earth 1 365.2564 7.496 Mars 1.52366 686.9796 7.495 Jupiter 5.20336 4332.8201
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.
NASA released a stunning image on Friday showing our home planet as well as the moon from Mars.
The ancient Greek astronomer Hipparchus noted the apsidal precession of the Moon's orbit (as the revolution of the Moon's apogee with a period of approximately 8.85 years); [4] it is corrected for in the Antikythera Mechanism (circa 80 BCE) (with the supposed value of 8.88 years per full cycle, correct to within 0.34% of current measurements). [5]
Even further out, Sedna has an extremely-high eccentricity of 0.855 due to its estimated aphelion of 937 AU and perihelion of about 76 AU, possibly under influence of unknown object(s). The eccentricity of Earth's orbit is currently about 0.016 7; its orbit is nearly circular.
The Noachian period occurred from 4.1 to 3.7 billion years ago, and little is known from direct measurements dating to the pre-Noachian period on Mars, between 4.5 billion and 4.1 billion years ...