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[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. [2] An IAU process will be established to assign borderline objects into either dwarf planet and other categories. [3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
A planet is any object in orbit around the Sun with a diameter greater than 2,000 km. (Eleven votes in favor) A planet is any object in orbit around the Sun whose shape is stable due to its own gravity. (Eight votes in favor) A planet is any object in orbit around the Sun that is dominant in its immediate neighbourhood. (Six votes in favor) [48 ...
The defining dynamic characteristic of a planet, according to the IAU definition, is that it has cleared its neighborhood. A planet that has cleared its neighborhood has accumulated enough mass to gather up or sweep away all the planetesimals in its orbit. In effect, it orbits its star in isolation, as opposed to sharing its orbit with a ...
Some geoscientists adhere to the formal definition of a planet that was proposed by the International Astronomical Union (IAU) in August 2006. [3] According to IAU definition of planet, a planet is an astronomical body orbiting the Sun that is massive enough to be rounded by its own gravity, and has cleared the neighbourhood around its orbit. [4]
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 ...
Alan Stern, the director of NASA's mission to Pluto, rejects the current IAU definition of planet, both in terms of defining dwarf planets as something other than a type of planet, and in using orbital characteristics (rather than intrinsic characteristics) of objects to define them as dwarf planets. [25]
A terrestrial planet, tellurian 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 .
Not all planets have atmospheres: their existence depends on the mass of the planet, and the planet's distance from the Sun – too distant and frozen atmospheres occur. Besides the four giant planets , three of the four terrestrial planets ( Earth , Venus , and Mars ) have significant atmospheres.