Sedna

An extreme trans-Neptunian object with a 10,000-year orbit — possibly a first member of the inner Oort Cloud.

Orbits Sun

About Sedna

90377 Sedna is a distant trans-Neptunian object on one of the most extreme orbits known. Its aphelion is ~937 AU and its orbital period about 11,400 years. Its highly eccentric, distantly-bound orbit — never coming closer than 76 AU from the Sun — makes it a candidate first member of the hypothetical inner Oort Cloud. Its orbit is part of the observational evidence supporting the hypothesized “Planet Nine.”

Physical Properties

Mean radius498 km

Bond albedo0.32

Orbit

OrbitsSun

Semi-major axis506 AU

Eccentricity0.8549

Inclination11.93°

Perihelion76.26 AU

Aphelion937 AU

Orbital period11400 yr

Gallery

Hand-picked mission imagery of Sedna sourced from NASA and partner archives. Click any photo for full resolution and source attribution.

Artist's concept: the planetoid Sedna at the cold outer edge of the solar system. NASA/JPL-Caltech · Public Domain u2014 NASA Media Usage Guidelines

Imagery on this page is provided by the original mission teams. Full attribution terms: Image Rights & Credits.

Sources & Further Reading

Numerical values (radius, mass, orbital elements, temperatures) are drawn from NASA NSSDC Planetary Fact Sheets, JPL Horizons, and the JPL Small-Body Database. Last refreshed: 2026-06-08 01:37:02.