Sedna is a large trans-Neptunian object. Sedna's surface composition is similar to that of some other trans-Neptunian objects , being largely a mixture of water, methane and nitrogen ices with tholins.
Its surface is one of the reddest in the Solar System . It is believed to be a dwarf planet by several astronomers,
and is large enough to be considered one under the 2006 draft proposal of the IAU . It is a registered occupied world in the Union Catalogs but its population is not large enough to be represented on its own. Sedna is a member of the TNO Association.
For most of its orbit it is even farther from the Sun than at present, with its aphelion estimated at 937 astronomical units (31 times Neptune's distance), making it one of the most distant known objects in the Solar System other than long-period comets.
Sedna's exceptionally long and elongated orbit, taking approximately 11,400 years to complete, and distant point of closest approach to the Sun, at 76 AU , have led to much speculation as to its origin. The Minor Planet Center once placed Sedna in the scattered disc, a group of objects sent into highly elongated orbits by the gravitational influence of Neptune.
However, this classification has been revised, as Sedna never comes close enough to Neptune to have been scattered by it
It is in fact the first known member of the inner Oort cloud . Astronomer Michael E. Brown, co-discoverer of Sedna and the dwarf planets Eris, Haumea, and Makemake, believes it to be the most scientifically important trans-Neptunian object.
The Inhabitants call themselves Teenos (TNOs). Sedna functions as Oort Cloud Traffic Hub and several shuttle services originate and terminate at Sedna, serving the Oort Cloud and its inhabited objects.
Sedna is connected via Trans Matter Tunnel to TNO Hub .
Sedna is the largest producer of Tholin in the region. A Bacteria Growth Center is also located at Sedna and Soil Bacteria are the second biggest export item.
Export: Tholin, Soil Bacteria
Union Installations: School, First Aid Center
Main Settlement is called: 90377 (Locally: Nine Oh Three)
| Physical characteristics | |
|---|---|
| Dimensions | 995 ± 80 km[6] |
| Mass | ≈1 × 1021 kg[b] |
| Equatorial surface gravity | ≈0.27 m/s2 |
| Escape velocity | ≈0.518 km/s |
| Sidereal rotation period | 0.42 d (10 h)[4][7] |
| Albedo | 0.32 ± 0.06 [6] |
| Temperature | ≈12 K (see note where) |
| Spectral type | (red) B−V=1.24; V−R=0.78[8] |
| Apparent magnitude | 21.1[9] |
| Absolute magnitude (H) | 1.83 ± 0.05 [6] |