Sednoid
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A sednoid is a trans-Neptunian object with a large semi-major axis, a distant perihelion and a highly eccentric orbit, similar to that of the dwarf planet Sedna. The consensus among astronomers is tha
Discovery image of Sedna, the eponymous and first known sednoid
Ceres RC3 Haulani Crater
Pluto in True Color High Res
Asteroid belt
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The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, i
Sednoid
…Inner Oort Cloud objects larger than 40 km, with a total mass in the range of 1×1022 kg, about the mass of Pluto and several times the mass of the asteroid belt. Trans-Neptunian objects category…
By far the largest object within the belt is the dwarf planet Ceres. The total mass of the asteroid belt is significantly less than Pluto's, and roughly twice that of Pluto's moon Charon.
In 1596, Johannes Kepler's sense of proportion for the planetary orbits led him to believe that an undiscovered planet lay between the orbits of Mars and Jupiter.
Giuseppe Piazzi, discoverer of Ceres, the largest object in the asteroid belt: Ceres was known as a planet, but later reclassified as an asteroid and from 2006 as a dwarf planet.
951 Gaspra, the first asteroid imaged by a spacecraft, as viewed during Galileo's 1991 flyby; colors are exaggerated