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7066 Nessus (/ˈnɛsəs/; from Νέσσος), provisional designation 1993 HA2, is a centaur on an eccentric orbit, located beyond Saturn in the outer Solar System. It was discovered on 26 April 1993, by astronomers of the Spacewatch program at the Kitt Peak National Observatory in Arizona, United States.[2] The dark and reddish minor planet is likely elongated and measures approximately 60 kilometers (37 miles) in diameter.[4][11] It was named after Nessus from Greek mythology.[2]

7066 Nessus
Discovery [2]
Discovered bySpacewatch
(D. Rabinowitz uncredited)[1]
Discovery siteKitt Peak National Obs.
Discovery date26 April 1993
MPC designation(7066) Nessus
Named after
Nessus (Greek mythology)[2]
1993 HA2
centaur[3][4][5] · distant[2]
Orbital characteristics[3]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 3
Observation arc11.08 yr (4,048 d)
Aphelion37.423 AU
Perihelion11.854 AU
24.639 AU
122.30 yr (44,670 d)
0° 0m 29.16s / day
Jupiter MOID6.400 AU
Physical characteristics
Mean diameter
57±17 km[6]
60±16 km[4][7]
RR (very red)[8]
B–V = 1.090±0.010[8]
V–R = 0.790±0.010[8]
V–I = 1.470±0.030[8]
B–R = 1.847[9]


Orbit and classificationEdit

Nessus is a centaur, a dynamically unstable population of minor planets between the classical asteroids and the trans-Neptunian objects. It orbits the Sun at a distance of 11.9–37.4 AU once every 122 years and 4 months (44,670 days; semi-major axis of 24.64 AU). Its orbit has an eccentricity of 0.52 and an inclination of 16° with respect to the ecliptic. At its perihelion (11.9 AU), it moves much closer to the Sun than Uranus (19.2 AU) but not as close as Saturn (9.6 AU), while at its aphelion (37.4 AU), it moves out well beyond the orbit of Neptune (30.1 AU).[3]

The orbits of centaurs are unstable due to perturbations by the giant planets. Nessus is an "SE object" because currently Saturn controls its perihelion and its aphelion is within the Kuiper belt. It is estimated to have a relatively long orbital half-life of about 4.9 million years.[13] Fifty clones of the orbit of Nessus suggest that it will not pass within 1 AU (or 150 million kilometers) of any planet for at least 20,000 years.[14]

Discovery and namingEdit

Nessus was discovered by David Rabinowitz (not officially credited), working with the Spacewatch program, at Kitt Peak National Observatory on 26 April 1993.[2][1] The discovery was announced on 13 May 1993 in a IAU Circular (IAUC 5789) of the Central Bureau for Astronomical Telegrams.[1] It was the third discovery of a centaur after 2060 Chiron and 5145 Pholus, discovered by Charles Kowal and David Rabinowitz in 1977 and 1992, respectively.[15] The body's observation arc begins with its official discovery observation at Kitt Peak in April 1993.[2]

This minor planet was named after Nessus, a centaur from Greek mythology, who poisoned and was killed by the divine hero Heracles.[2] The official naming citation was published by the Minor Planet Center on 22 April 1997 (M.P.C. 29671).[16]

Physical characteristicsEdit

Nessus has a very reddish color (RR),[8] with a B–R magnitude of 1.847 and 1.88, respectively.[4][9] Color indices were also determined by Bauer (2003) and Hainaut (2002, 2012).[5][17][18][19]

Rotation periodEdit

As of 2018, no rotational lightcurve of Nessus has been obtained from photometric observations. However, a brightness variation of 0.5 magnitude was measured in the 1990s, indicating that the body has a non-spherical, elongated shape.[12] The body's rotation period and pole remain unknown.[3][11]

Diameter and albedoEdit

According to the Herschel Space Observatory with its PACS instrument, Nessus measures 57 kilometers in diameter and its surface has an albedo of 0.086,[6] while infrared observations with the Spitzer Space Telescope gave a diameter of 60 kilometers with an albedo of 0.065.[7] The Collaborative Asteroid Lightcurve Link assumes a carbonaceous standard albedo of 0.057 and derives a diameter of 68.48 kilometers based on an absolute magnitude of 9.55.[11]

In popular cultureEdit

"Nessus" is an in-game location within the 2017 video game Destiny 2. However, Nessus as portrayed in the game is more similar to a planet than a small rocky/icy body, and has a substantial atmosphere and complex alien life. These differences are attributed to terraforming by machine lifeforms, giving Nessus an organic yet robotic aesthetic.[citation needed]


  1. ^ a b c "IAUC 5789: 1993 HA2". Central Bureau for Astronomical Telegrams. 13 May 1993. Retrieved 26 November 2018.
  2. ^ a b c d e f g h i "7066 Nessus (1993 HA2)". Minor Planet Center. Retrieved 26 November 2018.
  3. ^ a b c d e "JPL Small-Body Database Browser: 7066 Nessus (1993 HA2)" (2004-05-26 last obs.). Jet Propulsion Laboratory. Retrieved 26 November 2018.
  4. ^ a b c d e Johnston, Wm. Robert (7 October 2018). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 26 November 2018.
  5. ^ a b "Asteroid 7066 Nessus". Small Bodies Data Ferret. Retrieved 26 November 2018.
  6. ^ a b c Duffard, R.; Pinilla-Alonso, N.; Santos-Sanz, P.; Vilenius, E.; Ortiz, J. L.; Mueller, T.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region. XI. A Herschel-PACS view of 16 Centaurs" (PDF). Astronomy and Astrophysics. 564: 17. arXiv:1309.0946. Bibcode:2014A&A...564A..92D. doi:10.1051/0004-6361/201322377. Retrieved 26 November 2018.
  7. ^ a b c John Stansberry; 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". arXiv:astro-ph/0702538.
  8. ^ a b c d e Belskaya, Irina N.; Barucci, Maria A.; Fulchignoni, Marcello; Dovgopol, Anatolij N. (April 2015). "Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo". Icarus. 250: 482–491. Bibcode:2015Icar..250..482B. doi:10.1016/j.icarus.2014.12.004. Retrieved 26 November 2018.
  9. ^ a b Peixinho, N.; Delsanti, A.; Guilbert-Lepoutre, A.; Gafeira, R.; Lacerda, P. (October 2012). "The bimodal colors of Centaurs and small Kuiper belt objects". Astronomy and Astrophysics. 546: 12. arXiv:1206.3153. Bibcode:2012A&A...546A..86P. doi:10.1051/0004-6361/201219057. Retrieved 26 November 2018.
  10. ^ "Asteroid (7066) Nessus" (Ephemeris at epoch 58447 MJD). AstDyS-2, Asteroids – Dynamic Site; Department of Mathematics, University of Pisa, Italy. Retrieved 26 November 2018.
  11. ^ a b c d "LCDB Data for (7066) Nessus". Asteroid Lightcurve Database (LCDB). Retrieved 26 November 2018.
  12. ^ a b Davies, John K.; McBride, Neil; Ellison, Sara L.; Green, Simon F.; Ballantyne, David R. (August 1998). "Visible and Infrared Photometry of Six Centaurs". Icarus. 134 (2): 213–227. Bibcode:1998Icar..134..213D. doi:10.1006/icar.1998.5931. Retrieved 26 November 2018.
  13. ^ Horner, J.; Evans, N. W.; Bailey, M. E. (November 2004). "Simulations of the population of Centaurs - I. The bulk statistics" (PDF). Monthly Notices of the Royal Astronomical Society. 354 (3): 798–810. arXiv:astro-ph/0407400. Bibcode:2004MNRAS.354..798H. doi:10.1111/j.1365-2966.2004.08240.x. Retrieved 26 November 2018.
  14. ^ "Fifty clones of Centaur 7066 Nessus making passes within 150Gm". Archived from the original on 22 February 2013. Retrieved 26 April 2009.
    "The SOLEX page". Archived from the original on 29 April 2009.
  15. ^ "The third Centaur Nessus". The Centaur Research Project. Retrieved 26 November 2018.
  16. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 November 2018.
  17. ^ Bauer, James M.; Meech, Karen J.; Fernández, Yanga R.; Pittichova, Jana; Hainaut, Olivier R.; Boehnhardt, Hermann; et al. (November 2003). "Physical survey of 24 Centaurs with visible photometry". Icarus. 166 (1): 195–211. Bibcode:2003Icar..166..195B. doi:10.1016/j.icarus.2003.07.004. Retrieved 26 November 2018.
  18. ^ Hainaut, O. R.; Delsanti, A. C. (July 2002). "Colors of Minor Bodies in the Outer Solar System. A statistical analysis". Astronomy and Astrophysics: 641–664. Bibcode:2002A&A...389..641H. doi:10.1051/0004-6361:20020431. Retrieved 26 November 2018.
  19. ^ Hainaut, O. R.; Boehnhardt, H.; Protopapa, S. (October 2012). "Colours of minor bodies in the outer solar system. II. A statistical analysis revisited" (PDF). Astronomy and Astrophysics. 546: 20. arXiv:1209.1896. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. Retrieved 26 November 2018.

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