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Currently most of the objects of mass between 10 9 kg to 10 12 kg (less than 1000 teragrams (Tg)) listed here are near-Earth asteroids (NEAs). The Aten asteroid 1994 WR12 has less mass than the Great Pyramid of Giza, 5.9 × 10 9 kg. For more about very small objects in the Solar System, see meteoroid, micrometeoroid, cosmic dust, and ...
720,000 km/h (450,000 mi/h) [ 10] Orbital period. ~230 million years [ 10] The Solar System[ d] is the gravitationally bound system of the Sun and the objects that orbit it. [ 11] It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
Planets. Counter-Earth, a planet situated on the other side of the Sun from that of the Earth. Fifth planet (hypothetical), historical speculation about a planet between the orbits of Mars and Jupiter. Phaeton, a planet situated between the orbits of Mars and Jupiter whose destruction supposedly led to the formation of the asteroid belt.
f p = 0.2 to 0.5 (one fifth to one half of all stars formed will have planets) n e = 1 to 5 (stars with planets will have between 1 and 5 planets capable of developing life) f l = 1 (100% of these planets will develop life) f i = 1 (100% of which will develop intelligent life) f c = 0.1 to 0.2 (10–20% of which will be able to communicate)
Of those objects that orbit the Sun directly, the largest eight are the planets (including Earth), with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.
The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. There are eight planets within the Solar System; planets outside of the solar system are also known as exoplanets.
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 ...
Planetary core. The internal structure of the inner planets. The internal structure of the outer planets. A planetary core consists of the innermost layers of a planet. [1] Cores may be entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. [2] In the Solar System, core sizes range from about 20% (the Moon) to 85% ...