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It is the ninth-largest and tenth-most- massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is slightly less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets.
New Mexico State University Board of Regents Medal (1980) Rittenhouse Medal (1990) Clyde William Tombaugh / ˈtɒmbaʊ / (February 4, 1906 – January 17, 1997) was an American astronomer. He discovered the ninth planet Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt.
The decision to name the object Pluto was intended in part to honour Percival Lowell, as his initials made up the word's first two letters. [29] After discovering Pluto, Tombaugh continued to search the ecliptic for other distant objects. He found hundreds of variable stars and asteroids, as well as two comets, but no further planets. [30]
Planets in the Solar System. According to the IAU definition, there are eight planets in the Solar System, which are (in increasing distance from the Sun): [2] Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Jupiter is the largest, at 318 Earth masses, whereas Mercury is the smallest, at 0.055 Earth masses.
The outer planets Jupiter, Saturn, Uranus and Neptune, compared to the inner planets Earth, Venus, Mars, and Mercury at the bottom right The four outer planets, called giant planets or Jovian planets, collectively make up 99% of the mass known to orbit the Sun. [ h ] All four giant planets have multiple moons and a ring system, although only ...
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept ...
The written symbols for Mercury, Venus, Jupiter, and Saturn have been traced to forms found in late Greek papyri. [13] The symbols for Jupiter and Saturn are identified as monograms of the initial letters of the corresponding Greek names, and the symbol for Mercury is a stylized caduceus. [13]
Venus is the second planet from the Sun. It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth. Venus has by far the densest atmosphere of the terrestrial planets, composed mostly of carbon dioxide with a thick, global sulfuric acid cloud cover.