(84522) 2002 TC302

(84522) 2002 TC302, prov. designation: 2002 TC302, is a mid-sized trans-Neptunian object located in the outermost region of the Solar System. It was discovered on 9 October 2002, by American astronomers Mike Brown, Chad Trujillo and David Rabinowitz at the Palomar Observatory in California.[1] The resonant trans-Neptunian object stays in a 2:5 resonance with Neptune. It has a reddish color, a rotation period of 56.1 hours and measures at least 500 kilometers (310 miles) in diameter.

(84522) 2002 TC302
84522-2002tc302 hst.jpg
Hubble Space Telescope image of 2002 TC302 taken in 2005
Discovered byM. E. Brown
C. A. Trujillo
D. L. Rabinowitz
Discovery sitePalomar Obs.
Discovery date9 October 2002
(84522) 2002 TC302
TNO[3] · 2:5 resonant[4][5]
Orbital characteristics[3]
Epoch 1 July 2021 (JD 2459396.5)
Uncertainty parameter 2[3] · 3[1]
Observation arc20.49 yr (7,484 d)
Earliest precovery date5 August 2000
Aphelion71.382 AU
Perihelion39.169 AU
55.275 AU
410.97 yr (150,105 d)
0° 0m 8.64s / day
14 December 2058[a]
Physical characteristics
Dimensions543±18 × 460±11 km (projected area)[6]
Mean diameter
500±14 km (area equiv.)[6]
56.1 h[6]
IR (moderately red)[8]

Orbit and classificationEdit

2002 TC302 orbits the Sun at a distance of 39.2–71.4 AU once every 410 years and 12 months (150,105 days; semi-major axis of 55.28 AU). Its orbit has an eccentricity of 0.29 and an inclination of 35° with respect to the ecliptic.[3] In December 2058, It will come to perihelion (minimum distance from the Sun) at 39.2 AU,[3] which is about the same as Pluto's semi-major axis (average distance from the Sun). Given the long orbit that TNOs have around the Sun, 2002 TC302 comes to opposition in late October of each year at an apparent magnitude of 20.5.[10]

Both the Minor Planet Center (MPC) and the Deep Ecliptic Survey (DES) show 2002 TC302 to be a resonant trans-Neptunian object in a 2:5 resonance with Neptune, meaning it completes two orbits for every five orbits of Neptune.[4][5][11]

A still frame showing the motion of 2002 TC302 relative to Neptune being held stationary
The 2:5 resonance motion of 2002 TC302 (red) and the 2:3 resonance of Pluto (grey). Neptune is held stationary.

Physical characteristicsEdit

Comparison of 2002 TC302 with selected other trans-Neptunian objects

2002 TC302 has an absolute magnitude of 3.78.[3] It has an estimated diameter of 584.1+105.6
.[7] Using the Spitzer Space Telescope, it was previously estimated to have a diameter of 1145+337
,[8] which would have made it one of the largest TNOs. This overestimation was due to insufficient motion to allow for a good sky subtraction, and because 2002 TC302 was very close to a brighter background object.[7] Brown noted that the Spitzer measurement involved a very large potential error and that the object would likely be much smaller.[12]

The red spectra suggests that 2002 TC302 has very little fresh ice on its surface.[8] Its rotation period was initially estimated by Thirouin et al. to be 5.41 h, based on a light-curve amplitude of 0.04±0.01 mag.[13] However, this short rotation period was most likely an alias due to a bias for shorter and more easily discernable shorter periods. 2002 TC302 is highly oblate, and Ortiz et al. suggest a longer rotation period estimate of 56.1 hours.[6]

An occultation of a 15.3 magnitude star by 2002 TC302 on 28 January 2018 over Europe suggests that it has highly oblate shape with dimensions of 543.2±18 × 459.5±11 km and a projected axial ratio of a/c=1.18.[6] The area equivalent diameter of 2002 TC302 is 499.6 km.[6]

On 11 November 2021, an occultation across North America and Europe detected an oblate shape of 530 × 467 km (mean 499 km), in strong agreement with the 2018 occultation results. No satellites were detected.[14]

Possible satelliteEdit

The mean diameter of 2002 TC302 determined from occultations in 2018 is smaller than the larger diameter estimate of 584.1+105.6
by Spitzer in 2008. Despite the large uncertainty in the Spitzer's estimate, the difference of ~84 km between the two diameters is significant, implying that 2002 TC302 may have a large satellite with a possible size range of 100–300 km, nearly as large as 2002 TC302 itself.[15] This possible satellite is expected to orbit 2002 TC302 at a very close distance of less than 2000 km, close enough to slow down 2002 TC302's rotation through tidal interactions.[6]

If both the primary body and satellite are doubly tidally locked, then the expected orbital period of the satellite would be approximately 54 hours, equal to 2002 TC302's rotation. Given an orbital period of 54 hours, the satellite's estimated orbital separation from the primary would be 1780 km, with an angular separation of 58 milliarcseconds, too small to be resolved with current space telescopes such as Hubble. Under the assumption the satellite's diameter is 200 km, it would cause 2002 TC302's position to oscillate by 18 milliarcseconds as it orbits around its barycenter.[6]

See alsoEdit


  1. ^ 22 October 2058 ±2 days per JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 3-sigma.)


  1. ^ a b c d e f "84522 (2002 TC302)". Minor Planet Center. Retrieved 25 July 2021.
  2. ^ "MPEC 2002-V26 : 2002 TC302". Minor Planet Electronic Circular. 7 November 2002.
  3. ^ a b c d e f g "JPL Small-Body Database Browser: 84522 (2002 TC302)" (2021-01-31 last obs.). Jet Propulsion Laboratory. Retrieved 25 July 2021.
  4. ^ a b Marc W. Buie. "Orbit Fit and Astrometric record for 84522". Southwest Research Institute. Retrieved 25 July 2021.The Deep Ecliptic Survey Object Classifications
  5. ^ a b Johnston, Wm. Robert (18 August 2020). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 25 July 2021.
  6. ^ a b c d e f g h i j Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Duffard, E.; Morales, N. (18 May 2020). "The large Trans-Neptunian Object 2002 TC302 from combined stellar occultation, photometry and astrometry data". Astronomy & Astrophysics. A134: 639. arXiv:2005.08881. doi:10.1051/0004-6361/202038046. S2CID 218673812.
  7. ^ a b c d e Fornasier, S.; Lellouch, E.; Müller, T.; Santos-Sanz, P.; Panuzzo, P.; Kiss, C.; et al. (July 2013). "TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of nine bright targets at 70–500 μm". Astronomy & Astrophysics. 555: A15. arXiv:1305.0449. Bibcode:2013A&A...555A..15F. doi:10.1051/0004-6361/201321329. ISSN 0004-6361. S2CID 119261700. A15.
  8. ^ a b c John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; et al. (2007). Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book..161S.
  9. ^ a b Tegler, Stephen C. (2006-01-26). "Kuiper Belt Object Magnitudes and Surface Colors". Archived from the original on 2006-09-01. Retrieved 2006-11-05.
  10. ^ "(84522) 2002 TC302". Minor Planet Center. 2010-07-23. Retrieved 2010-10-24.
  11. ^ "=MPEC 2009-C70 :Distant Minor Planets (2009 FEB. 28.0 TT)". Minor Planet Electronic Circular. 10 November 2009.
  12. ^ Brown, Michael E. "How many dwarf planets are there in the outer solar system?". California Institute of Technology. Retrieved 31 August 2016.
  13. ^ Thirouin, A.; Ortiz, J. L.; Campo Bagatin, A.; Pravec, P.; Morales, N.; Hainaut, O.; et al. (August 2012). "Short-term variability of 10 trans-Neptunian objects". Monthly Notices of the Royal Astronomical Society. 424 (4): 3156–3177. arXiv:1207.2044. Bibcode:2012MNRAS.424.3156T. doi:10.1111/j.1365-2966.2012.21477.x. ISSN 0035-8711. S2CID 53467482.
  14. ^ Frappa, Eric. "2002 TC302 preliminary occultation path". Retrieved 15 November 2021.
  15. ^ Starr, Michelle (22 May 2020). "Astronomers May Have Spotted a Tiny Moon in The Outer Solar System".

External linksEdit