Sedna (dwarf planet)
Distant body in the outer Solar System
Sedna (minor-planet number 90377) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. It was discovered in 2003, and is roughly 1,000 km in diameter. Spectroscopic analysis has revealed its surface to be a mixture of the solid ices of water, carbon dioxide, and ethane, along with sedimentary deposits of methane-derived, reddish-colored tholins, a chemical makeup similar to the surfaces of other trans-Neptunian objects.
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