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Other dates of astronomical significance are: northern solstice, 27 June; southward equinox, 36 September; southern solstice, 12 December; perihelion, 31 November; and aphelion, 31 May. Pickering's inclusion of Mars dates in a 1916 report of his observations may have been the first use of a Martian calendar in an astronomical publication. [25]
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.
Previous perihelion passages were in 1986, 2061, and 2134. 2221 May 27 Near-Earth asteroid (285263) 1998 QE 2 will pass Earth at a distance of 0.038 AU (5.7 million km; 3.5 million mi). [61] 2221 Triple conjunction of Mars and Saturn: 2223 December 2 At 12:39 UTC, Mars will occult Jupiter, this comes after a gap of 836 Earth years. [31] [42] 2227
Upon discovery, it was classified as Mars-crosser by the Minor Planet Center. Its orbit is well determined as it is currently (January 2021) based on 131 observations with a data-arc span of 1652 days. [1] 2016 CP 31 has an absolute magnitude of 19.5 which gives a characteristic diameter of 400 m. [1]
The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition. [192] [193] [194] Mars seen through a 16-inch amateur telescope, at 2020 opposition. The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05. [19]
As on Earth, there is a second form of precession: the point of perihelion in Mars's orbit changes slowly, causing the anomalistic year to differ from the sidereal year. However, on Mars, this cycle is 43,000 Martian years (81,000 Earth years) rather than 112,000 years as on Earth.
Apsidal precession is considered positive when the orbit's axis rotates in the same direction as the orbital motion. An apsidal period is the time interval required for an orbit to precess through 360°, [2] which takes the Earth about 112,000 years and the Moon about 8.85 years. [3]