(307261) 2002 MS4

(307261) 2002 MS4 is a large classical Kuiper belt object,[2] the second-largest known object in the Solar System without a name, after (225088) 2007 OR10. It was discovered in 2002 by Chad Trujillo and Michael Brown.

Brown's website lists it as nearly certain to be a dwarf planet.[8] The Spitzer Space Telescope estimated it to have a diameter of 726±123 km.[9] The Herschel team estimates it to be 934±47 km, which would make it one of the 10 largest TNOs currently known[5] and large enough to be considered a dwarf planet under the 2006 draft proposal of the IAU.[10] It is currently 47.2 AU from the Sun[7] and will come to perihelion in 2123.[4]

It has been observed 55 times, with precovery images back to April 8, 1954.[4]

(307261) 2002 MS4
2002 MS4 orbit 2018
Orbit of 2002 MS4 is similar but more inclined than 50000 Quaoar. Positions on 1/1/2018 are shown.
Discovered by Chad Trujillo,
Michael E. Brown
Discovery date 18 June 2002
MPC designation 2002 MS4
Cubewano (MPC)[2]
ScatExt (DES)[3]
Orbital characteristics[4]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 3
Observation arc 20569 days (56.31 yr)
Earliest precovery date April 8, 1954
Aphelion 47.740 AU (7.1418 Tm)
Perihelion 35.694 AU (5.3397 Tm)
41.717 AU (6.2408 Tm)
Eccentricity 0.14439
269.45 yr (98415.8 d)
4.58 km/s
0° 0m 13.168s / day
Inclination 17.677°
Earth MOID 34.7228 AU (5.19446 Tm)
Jupiter MOID 30.7148 AU (4.59487 Tm)
TJupiter 5.464
Physical characteristics
Dimensions 934±47 km[5]
Temperature ≈ 43 K
V−R=0.38 [6]
3.5±0.4 (R-band)[5]
Earth Moon Dysnomia Dysnomia Eris Eris Charon Charon Nix Nix Kerberos Kerberos Styx Styx Hydra Pluto Pluto Makemake Makemake Namaka Namaka Hi'iaka Hi'iaka Haumea Haumea Salacia Salacia Actaea 2002 MS4 2002 MS4 Sedna Sedna 2007 OR10 2007 OR10 Weywot Weywot Quaoar Quaoar Vanth Vanth Orcus Orcus File:EightTNOs.png
Artistic comparison of Pluto, Eris, Makemake, Haumea, Sedna, 2002 MS4, 2007 OR10, Quaoar, Salacia, Orcus, and Earth along with the Moon.


  1. ^ "MPEC 2002-W27 : 2002 MS4, 2002 QX47, 2002 VR128". IAU Minor Planet Center. 2002-11-21. Retrieved 2009-08-26.
  2. ^ a b "MPEC 2009-P26 :Distant Minor Planets (2009 AUG. 17.0 TT)". IAU Minor Planet Center. 2009-08-07. Retrieved 2009-08-31.
  3. ^ Marc W. Buie (2008-05-03). "Orbit Fit and Astrometric record for 02MS4". SwRI (Space Science Department). Archived from the original on 4 June 2011. Retrieved 2009-08-31.
  4. ^ a b c d "JPL Small-Body Database Browser: 307261 (2002 MS4)" (2009-09-19 last obs.). Jet Propulsion Laboratory. Retrieved 7 April 2016.
  5. ^ a b c d Vilenius, E.; Kiss, C.; Mommert, M.; et al. (2012). ""TNOs are Cool": A survey of the trans-Neptunian region VI. Herschel/PACS observations and thermal modeling of 19 classical Kuiper belt objects". Astronomy & Astrophysics. 541: A94. arXiv:1204.0697Freely accessible. Bibcode:2012A&A...541A..94V. doi:10.1051/0004-6361/201118743.
  6. ^ Tegler, Stephen C. (2006-01-26). "Kuiper Belt Object Magnitudes and Surface Colors". Archived from the original on November 16, 2007. Retrieved 2006-11-05.
  7. ^ a b "AstDyS 2002MS4 Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 2009-09-04. Retrieved 2009-08-27.
  8. ^ Michael E. Brown. "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Archived from the original on 2011-10-18. Retrieved 2011-08-25.
  9. ^ Stansberry, Grundy, Brown, Spencer, Trilling, Cruikshank, Luc Margot Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope (2007) Preprint arXiv
  10. ^ O. Gingerich (2006). "The Path to Defining Planets" (PDF). Harvard-Smithsonian Center for Astrophysics and IAU EC Planet Definition Committee chair. Retrieved 2007-03-13.

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