Mercury is the closest planet to the Sun and is the smallest of the eight planets being only slightly larger than our moon. Mercury image: NASA/JHUAPL Venus image: NASA/JPL-Caltech Earth image: NASA/Apollo 17 crew Mars image: ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA The terrestrial planets: Mercury, Venus, Earth and Mars, sized to scale. These types of planets also have few moons, a molten core and can have surface features like valleys, mountains and volcanoes. Terrestrial planets are planets with a solid surface, often made up of rock or metals. Astronomers who use the geophysical definition of a planet would also include the Moon as a terrestrial planet.
Terrestrial planets include the four closest planets to the Sun located between the Sun and the asteroid belt Mercury, Venus, Earth and Mars. Terrestrial and Giant Planets in order from the Sun Terrestrial Planets Johns Hopkins APL/Mike Yakovlev Planet Order from the SunĪll planets and dwarf planets recognized by the IAU will be included and separated by three categories of planets Terrestrial, Giant and Dwarf planets. The IAU currently recognizes five dwarf planets:īased on the geophysical definition of a planet, there are several satellite and dwarf planets in the solar system and likely more that haven’t been discovered. Many professionals in the field also criticize the IAU definition of trying to limit the number of planets with the most recent change to the definition, as it was ultimately responsible for Pluto being removed as the ninth planet and re-labeled a dwarf planet. Stern’s definition thus counts dwarf planets and planetary-mass moons as planets. When compared to the IAU planet definition, planetary scientist Alan Stern’s 2018 definition excludes the first point (that a planet be in orbit around the sun) and the third point (that a planet has cleared the neighborhood around its orbit).
Have cleared away any other objects of similar size near its orbit around the Sun.Īstronomers and planetary scientists did not unanimously agree with the new IAU definition and was contested by planetary scientists who prefer the geophysical definition of a planet.Have enough gravity to force it into a spherical shape,.The most recent definition of a planet was released in 2006 by the International Astronomical Union (IAU), an organization responsible for classifying astronomical objects. There is an ongoing debate about the number of planets in our solar system. In addition to the planets, our solar system also includes dwarf planets, moons, asteroids, comets, and meteoroids. The order of the eight official planets from the Sun, starting closest and moving outward: Our solar system is located in the Orion spiral arm of the Milky Way Galaxy and contains eight official planets that orbit counterclockwise around the Sun.
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