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| Sedna (minor planet) | |
|---|---|
| Name | Sedna |
| Designation | 90377 |
| Discovery date | 2003-11-14 |
| Discoverer | Mike Brown, Chad Trujillo, David Rabinowitz |
| Aphelion | ~937 AU |
| Perihelion | ~76 AU |
| Semimajor axis | ~518 AU |
| Eccentricity | ~0.855 |
| Period | ~11,400 yr |
| Inclination | ~11.9° |
| Mean diameter | ~1000 km |
| Absolute magnitude | 1.8 |
Sedna (minor planet) is a distant trans-Neptunian object discovered in 2003 that occupies one of the most remote known orbits in the Solar System. It has attracted attention in studies connected to Kuiper Belt, Oort cloud, Planet Nine hypotheses and solar system formation scenarios. Sedna's extreme orbital elements and red surface have made it a focal point for research by astronomers at institutions such as Caltech, Harvard–Smithsonian Center for Astrophysics, NASA and observatories including Palomar Observatory, Mauna Kea and European Southern Observatory facilities.
Sedna was discovered by a team composed of Mike Brown, Chad Trujillo, and David Rabinowitz using the 48-inch Samuel Oschin Telescope at Palomar Observatory during a survey influenced by earlier surveys like the Spacewatch and Deep Ecliptic Survey. The discovery announcement followed confirmation via follow-up observations at Keck Observatory and Magellan Observatory. The name Sedna derives from the sea goddess of the Inuit and was approved by the International Astronomical Union following conventions also used for objects such as Eris, Haumea, and Makemake. The naming process intersected with debates involving researchers from California Institute of Technology, Yale University, and the Smithsonian Institution over classification and public communication.
Sedna's orbit is highly eccentric and distant, with perihelion near the realm of Kuiper Belt objects and aphelion extending into regions often associated with the inner Oort cloud. Its semimajor axis, eccentricity, and inclination place it among detached objects distinct from classical Pluto-like resonant populations such as the Plutino group and the scattered disk exemplified by Eris and 2007 OR10. Debates over classification have engaged researchers studying scattered disc, inner Oort cloud, and hypothetical perturbers like Nemesis and the proposed Planet Nine; similar discussions occurred for objects such as 2012 VP113 and (90377) Sedna's contemporaries. Orbital solutions have been refined using dynamical models developed at University of Arizona, University of California, Berkeley, and University of Michigan.
Spectroscopic and photometric observations from facilities including Hubble Space Telescope, Spitzer Space Telescope, Subaru Telescope, and Very Large Telescope indicate Sedna has a very red surface, similar to bodies like 20000 Varuna and Quaoar. Ice species detected or inferred on similar TNOs include water ice, methane, and nitrogen ices, with surface processing attributed to irradiation by solar wind, cosmic rays, and micrometeorite impacts. Estimates of Sedna's diameter, based on thermal modeling by teams affiliated with Jet Propulsion Laboratory and European Space Agency, range around a thousand kilometers, placing it near the threshold for hydrostatic equilibrium debated in classifications alongside Ceres and Pluto. Albedo measurements and rotational lightcurves from Gemini Observatory and Arecibo Observatory-era radar constraints remain limited, so questions about axial tilt and internal differentiation remain topics for groups at MIT and University of Oxford.
Several origin scenarios have been proposed by theoreticians at institutions such as Princeton University, Institute for Advanced Study, Max Planck Institute for Solar System Research, and University of Tokyo. Hypotheses include perturbation by a passing star during the Sun's residence in a birth cluster, as in models inspired by encounters in clusters studied by Fred C. Adams and colleagues; scattering by giant planets during early migrations described in the Nice model; emplacement by a yet-unseen massive planet analogous to Planet Nine proposed by researchers at Caltech and University of California, Santa Cruz; or capture from another stellar system as simulated by groups at University of Cambridge and University of Colorado Boulder. Comparisons are often made with distant objects discovered by surveys like Pan-STARRS, Sloan Digital Sky Survey, and the Outer Solar System Origins Survey to constrain formation timescales and dynamical histories.
Observational campaigns involving Hubble Space Telescope, James Webb Space Telescope, Keck Observatory, and ground-based wide-field surveys such as Pan-STARRS and Zwicky Transient Facility have monitored Sedna to refine orbit and physical parameters. Proposals for spacecraft missions have been considered by teams at NASA Jet Propulsion Laboratory, European Space Agency and research groups inspired by missions like New Horizons and Voyager program; these proposals face challenges similar to those encountered in mission planning for Uranus and Neptune orbiters. Instrument concepts include cryogenic infrared spectrometers and radio science experiments modeled on instruments from Cassini–Huygens and Rosetta, but no mission has been selected to date.
Sedna has entered public and cultural discourse alongside other high-profile discoveries such as Pluto, Eris, and the hypothesized Planet Nine, inspiring coverage in outlets connected to National Geographic, BBC, Scientific American, and programs produced by NOVA and Discovery Channel. It appears in speculative fiction and documentaries that explore themes similar to those in works referencing Oort cloud and Kuiper Belt settings, and has been discussed in lectures at institutions like Smithsonian Institution and American Museum of Natural History. Sedna's name, drawn from Inuit tradition, has also been referenced in art exhibitions and outreach programs coordinated by organizations such as Royal Astronomical Society and International Astronomical Union committees.
Category:Trans-Neptunian objects Category:Minor planets