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Astronomers discover Sedna, a distant trans-Neptunian dwarf planet.

Historical image related to Astronomers discover Sedna, a distant trans-Neptunian dwarf planet. from November 14, 2003

Sedna (dwarf planet)

Distant, small body in the Solar System

Sedna (minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. Discovered in 2003, the frigid planetoid is one of the reddest known among Solar System bodies. Detailed spectroscopic…
Source: Wikipedia (CC BY-SA)

Dwarf planet

Small planetary-mass object

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…
Source: Wikipedia (CC BY-SA)