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It is slightly shorter than the sidereal year due to the precession of Mars' rotational axis. The precession cycle is 93,000 Martian years (175,000 Earth years), much longer than on Earth. Its length in tropical years can be computed by dividing the difference between the sidereal year and tropical year by the length of the tropical year.
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 ...
In astronomy, the rotation period or spin period [1] of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the sidereal rotation period (or sidereal day ), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars ( inertial space ).
In practice, only 1:1 ratio (geosynchronous) and 1:2 ratios (semi-synchronous) are common. Geosynchronous orbit (GSO): An orbit around the Earth with a period equal to one sidereal day, which is Earth's average rotational period of 23 hours, 56 minutes, 4.091 seconds. For a nearly circular orbit, this implies an altitude of approximately 35,786 ...
The March equinox itself precesses slowly westward relative to the fixed stars, completing one revolution in about 25,800 years, so the misnamed "sidereal" day ("sidereal" is derived from the Latin sidus meaning "star") is 0.0084 seconds shorter than the stellar day, Earth's actual period of rotation relative to the fixed stars. [3]
The prefix areo-derives from Ares, the ancient Greek god of war and counterpart to the Roman god Mars, with whom the planet was identified. The modern Greek word for Mars is Άρης (Áris). As with all synchronous orbits, an areosynchronous orbit has an orbital period equal in length to the primary's sidereal day.
“The sun does not come back to the same point in the sky every year,” explains Athen Chimenti, an astrologer, educator, and creator of Mastering the Zodiac. ... Feb 14 - Mar 9. Sidereal Pisces ...
The Astronomical Almanac for 1984 through 2002 were based on JPL ephemeris DE200, and from 2003 to 2014 the Astronomical Almanac was based on JPL ephemeris DE405. [9] As of 2022, the Almanac is derived from DE430. [15] The JPL ephemerides are widely used for planetary science; some examples are included in the Notes and References.