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Given the different Sun incidence in different positions in the orbit, it is necessary to define a standard point of the orbit of the planet, to define the planet position in the orbit at each moment of the year w.r.t such point; this point is called with several names: vernal equinox, spring equinox, March equinox, all equivalent, and named considering northern hemisphere seasons.
The mean calendar year of such a calendar approximates the sidereal year. Leaping from one lunation to another, but one Sidereal year is the period between two occurrences of the sun, as measured by the stars' solar calendar, which is derived from the Earth's orbit around the sun every 28 years. [3]
Most planets rotate on their axes in an anticlockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Earth days—the slowest rotation of any planet. This Venusian sidereal day lasts therefore longer than a Venusian year (243 versus 224.7 Earth days).
For instance, for a large portion of names ending in -s, the oblique stem and therefore the English adjective changes the -s to a -d, -t, or -r, as in Mars–Martian, Pallas–Palladian and Ceres–Cererian; [note 1] occasionally an -n has been lost historically from the nominative form, and reappears in the oblique and therefore in the English ...
Initially, the names given to minor planets followed the same pattern as the other planets: names from Greek or Roman myths, with a preference for female names. With the discovery in 1898 of the first body found to cross the orbit of Mars, a different choice was deemed appropriate, and 433 Eros was chosen.
The seasons occur because the Earth's axis of rotation is not perpendicular to its orbital plane (the plane of the ecliptic) but currently makes an angle of about 23.44° (called the obliquity of the ecliptic), and because the axis keeps its orientation with respect to an inertial frame of reference. As a consequence, for half the year the ...
An asteroid called 2020 CD3 was bound to Earth for several years before leaving the planet's orbit in 2020 and another called 2022 NX1 became a mini-moon of Earth in 1981 and 2022 and will return ...
During a year, there are large surface temperature swings on the surface between −78.5 °C (−109.3 °F) to 5.7 °C (42.3 °F) [c] similar to Earth's seasons, as both planets have significant axial tilt, Earth at 23.5 degrees and Mars at 25 degrees. Mars was formed approximately 4.5 billion years ago.