Search results
Results from the WOW.Com Content Network
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.
Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. Mars is the only presently known example of a desert planet, a rocky planet with a surface akin to that of Earth's hot deserts. The red-orange appearance of the Martian surface is caused by rust. [41]
The diagram shows a Hohmann transfer orbit to bring a spacecraft from a lower circular orbit into a higher one. It is an elliptic orbit that is tangential both to the lower circular orbit the spacecraft is to leave (cyan, labeled 1 on diagram) and the higher circular orbit that it is to reach (red, labeled 3 on diagram).
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]
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
A grazer is an object with a perihelion below the aphelion of Mars (1.67 AU) but above the Martian perihelion (1.38 AU). [1] The JPL SBDB lists 13,500 Mars-crossing asteroids. Only 18 MCAs are brighter than absolute magnitude (H) 12.5, [ 2 ] which typically makes these asteroids with H<12.5 more than 13 km in diameter depending on the albedo .
The spin axis of Mars, as with many bodies, precesses over millions of years. At present, the solstices nearly coincide with Mars's aphelion and perihelion. This results in one hemisphere, the Southern, receiving more sunlight in summer and less in winter, and thus more extreme temperatures, than the Northern.