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A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Venus, Earth and Mars. Among astronomers who use the geophysical definition of a planet, two or three ...
Of the Solar System's eight planets and its nine most likely dwarf planets, six planets and seven dwarf planets are known to be orbited by at least 300 natural satellites, or moons. At least 19 of them are large enough to be gravitationally rounded; of these, all are covered by a crust of ice except for Earth's Moon and Jupiter's Io . [ 1 ]
e. The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System – Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres. Earth is the only terrestrial planet known to have an active hydrosphere . Terrestrial planets are substantially different from ...
A civilization with energy on the scale of its own galaxy, with an energy consumption of ≈4 × 10 44 erg/sec. [2] Lemarchand defined civilizations of this type as having access to energy comparable to the luminosity of the entire Milky Way galaxy, about 4 × 10 44 erg/sec (4 × 10 37 watts).
A class of extrasolar planets whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close—between approximately 0.015 and 0.5 AU (2.2 × 10 ^ 6 and 74.8 × 10 ^ 6 km)—to their parent stars, whereas Jupiter orbits its parent star (the Sun) at 5.2 AU (780 × 10 ^ 6 km), causing low ...
The Oort cloud (/ ɔːr t, ʊər t /), [1] sometimes called the Öpik–Oort cloud, [2] is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). [3] [note 1] [4] The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in
The Atlas of Terrestrial Group Planets and their Moons ( Russian: Атлас планет Земной группы и их спутников) is a Soviet -era planetary atlas published in the Russian language in Moscow. It summarizes Soviet and American planetary science results in thematic maps of Mercury, Venus, the Moon, Mars, Phobos, and ...
The use of astronomical symbols for the Sun and Moon dates to antiquity. The forms of the symbols that appear in the original papyrus texts of Greek horoscopes are a circle with one ray () for the Sun and a crescent for the Moon. [ 3] The modern Sun symbol, a circle with a dot (☉), first appeared in Europe in the Renaissance.