Enigmas in Our Solar System
New Planets Discovered
Image Credit: NASA/JPL-Caltech
Artist's Conception: Sedna - Sedna is extremely far from the Sun, in the coldest known region of our Solar System, where temperatures never rise above minus minus 400 degrees Fahrenheit (240 degrees Celsius). The planetoid is usually even colder, because it approaches the Sun only briefly during its 10,500-year solar orbit. At its most distant, Sedna is 130 billion kilometers (84 billion miles) from the Sun, which is 900 times Earth's solar distance.

Sedna was discovered on November 14, 2003 by a CalTech team, using the 48-inch Samuel Oschin Telescope at Palomar Observatory. The object lies more than 8 billion miles from the Earth, making it the most distant object ever observed in the solar system. Its official IAU provisional designation was minor planet 2003 VB12, but as of September 28, 2004 it officially became known as Sedna after the Inuit goddess of arctic sea life.

The Growing Solar System Family
Credit: Gemini Observatory

The Growing Solar System Family

The orbit of 2003 UB 313 (shown in red) relative to the other planets in the solar system and Sedna (large white oval). 

Credit: Gemini Observatory
Orbital Close-up

The "original" nine planets are indicated as well as 2003 UB313 (in red) and part of Sedna's orbit. 2003 UB313 appears to cross inside of Pluto's orbit but this is due to the fact that 2003 UB313 is tilted by about 45º relative to the rest of the solar system.

SOURCE: Gemini Observatory

Sedna Reveals Pristine Surface in
Gemini Near-infrared Spectra
Credit: Gemini artwork by Jon Lomberg

Recent spectroscopic studies of infrared light reflected from the surface of Sedna reveal that it is probably unlike Pluto and Charon since Sedna's surface does not display evidence for a large amount of either water or methane ice. Due to Sedna’s extreme distance from the Sun, the frigid surface has probably been untouched for millions of years by anything except cosmic rays and solar ultraviolet radiation.

Gemini Observatory astronomer Chad Trujillo led an effort by the same California Institute of Technology research team responsible for Sedna's original discovery to obtain spectra of this distant planetoid using the Near Infrared Imager (NIRI) on Gemini North. Their aim was to better understand the surface of this distant world and how it has evolved since its formation. “It is likely that Sedna has experienced an extremely isolated life in the outskirts of our solar system,” said Trujillo. “Out there beyond what we used to think was the edge of the solar system, interactions or collisions between bodies are probably very rare. Our observations confirm what you would expect from a surface that has been so far out in our solar system for such a long time and exposed to space weathering.”

SOURCE: Gemini Observatory

More Information

Image Credit: NASA, ESA, A. Feild (STScI)
  1. "Discovery Circumstances: Numbered Minor Planets (90001)-(95000)". IAU: Minor Planet Center.
  2. Buie, Marc W. (2007-08-13). "Orbit Fit and Astrometric record for 90377". Deep Ecliptic Survey
  3. Brown, Michael E.. "The largest Kuiper belt objects" (PDF)
  4. Stansberry, John; Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". University of Arizona, Lowell Observatory, California Institute of Technology, NASA Ames Research Center, Southwest Research Institute, Cornell University
  5. Radius of 590 km and density of 0.97 = 8.3 × 1020 kg mass. Radius of 900 km and density of 2.3 = 7.0 × 1021 kg mass
  6. Tegler, Stephen C. (2006-01-26). "Kuiper Belt Object Magnitudes and Surface Colors"
  7. "AstDys (90377) Sedna Ephemerides". Department of Mathematics, University of Pisa, Italy
  8. "Horizons Output for Sedna 2076/2114" Horizons
  9. "JPL Small-Body Database Browser: 90377 Sedna (2003 VB12)". 2007-11-08 last obs
  10. At present, though, Eris (dwarf planet) is farther from the Sun than Sedna.
  11. Lowell DES Perihelion Epoch = 2000.0 + (2479283.2278 − 2451545.0)/365.25 = 2075.9431 = (2076-1-1 - 20.7768 days) = 2075-12-11 (Julian Date Converter)
  12. Morbidelli, Alessandro; Harold F. Levison (2004). "Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna)". The Astronomical Journal '128': 2564–2576. doi:10.1086/424617. (Original Preprint)
  13. "The Challenge of Sedna". Harvard-Smithsonian Center for Astrophysics
  14. Gomes, Rodney S.; John J. Matese, and Jack J. Lissauer (2006). "A distant planetary-mass solar companion may have produced distant detached objects". Icarus 184: 589–601. doi:10.1016/j.icarus.2006.05.026.
  15. Gaudi, B. Scott; Krzysztof Z. Stanek, Joel D. Hartman, Matthew J. Holman, Brian A. McLeod (CfA) (2005). "On the Rotation Period of (90377) Sedna". Astrophys.J. 629: L49–L52. doi:10.1086/444355.
  16. D. L. Rabinowitz; K. M. Barkume, M. E. Brown, H. G. Roe, M. Schwartz, S. W. Tourtellotte, C. A. Trujillo (2006). "Photometric Observations Constraining the Size, Shape, and Albedo of 2003 EL61, a Rapidly Rotating, Pluto-Sized Object in the Kuiper Belt" (preprint on arXiv). The Astrophysical Journal 639 (2): 1238–1251. doi:10.1086/499575
  17. M. Grundy, K. S. Noll, D. C. Stephens. "Diverse Albedos of Small Trans-Neptunian Objects". Lowell Observatory, Space Telescope Science Institute.
  18. McKee, Maggie (2005). "Distant planetoid Sedna gives up more secrets". news service
  19. Alexander, Amir (18 April 2005). "Sedna: Mysterious Planetoid Slowly Yielding Up Its Secrets". The Planetary Society
  20. Barucci, M. A.; D. P. Cruikshank, E. Dotto, F. Merlin, F. Poulet, C. Dalle Ore, S. Fornasier and C. de Bergh (2005). "Is Sedna another Triton?". Astronomy & Astrophysics 439: L1–L4. doi:10.1051/0004-6361:200500144
  21. Jewitt, David, Morbidelli, Alessandro, & Rauer, Heike. (2007). Trans-Neptunian Objects and Comets: Saas-Fee Advanced Course 35. Swiss Society for Astrophysics and Astronomy. Berlin: Springer. ISBN 3540719571
  22. Lykawka, Patryk Sofia & Mukai, Tadashi. (2007). Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation. Icarus Volume 189, Issue 1, July , Pages 213-232. doi:10.1016/j.icarus.2007.01.001
  23. Kenyon, Scott J.; Benjamin C. Bromley (2 December 2004). "Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits". Nature 432: 598–602. doi:10.1038/nature03136
  24. Evidence for an Extended Scattered Disk?
  25. Jewitt, D., A. Delsanti, The Solar System Beyond The Planets in Solar System Update : Topical and Timely Reviews in Solar System Sciences , Springer-Praxis Ed., ISBN 3-540-26056-0 (2006) Preprint of the article (pdf)
  26. Elliot, J. L., S. D. Kern, K. B. Clancy, A. A. S. Gulbis, R. L. Millis, M. W. Buie, L. H. Wasserman, E. I. Chiang, A. B. Jordan, D. E. Trilling, and K. J. Meech The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population. The Astronomical Journal, 129 (2006), pp. preprint
  27. Brown, Michael E.. "The Dwarf Planets". California Institute of Technology, Department of Geological Sciences
  28. Stern–Levison parameter (using unlikely highest estimated mass) = ((7 × 1021) / (5.9736 × 1024))^2 / 12,059 yr = 1.14 × 10−10 (Sedna 1.14 × 10−10) / (Pluto 1.95 × 10−8) = 5.8 × 10−3
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