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Discovery and designation
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| Discovered by | David L. Rabinowitz |
| Discovery date | April 26, 1993 |
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Designations
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| Named after | Nessus |
| Alternate name(s) | 1993 HA2 |
| Minor planet category |
Centaur |
| Adjective | Nessian |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 37.483 AU (Q) 5607.4 Gm |
| Perihelion | 11.826 AU (q) 1769.1 Gm |
| Semi-major axis | 24.655 AU (a) 3688.3 Gm |
| Eccentricity | 0.520 |
| Orbital period | 44714.802 d 122.42 yr |
| Average orbital speed | 5.57 km/s |
| Mean anomaly | 43.762° |
| Inclination | 15.647° |
| Longitude of ascending node | 31.216° |
| Argument of perihelion | 170.814° |
| Dimensions | 60±16 km[2][3] |
| Mass | ~1.6×1017 kg |
| Mean density | 2.0? g/cm3 |
| Equatorial surface gravity | ~0.0148 m/s2 |
| Equatorial escape velocity | ~0.0280 km/s |
| Sidereal rotation period |
? d |
| Axial tilt | ?° |
| Pole ecliptic latitude | ? |
| Pole ecliptic longitude | ? |
| Geometric albedo | 0.06[2] |
| Temperature | ~56 K |
| Spectral type | ? |
| Apparent magnitude | ~23.4[4] |
| Absolute magnitude (H) | 9.6[1] |
7066 Nessus ( /ˈnɛsəs/; from Greek: Νέσσος) is a centaur (a type of icy planetoid) that was discovered by David L. Rabinowitz, working with Spacewatch, at Kitt Peak on 26 April 1993. It was the second centaur found by him (5145 Pholus being his previous find), and the third centaur discovery (2060 Chiron, discovered by Charles Kowal in 1977, was the first). Nessus was officially announced on May 13, 1993, in IAUC 5789 with designation 1993 HA2.
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7066 Nessus has an orbital period of 122.4 years, an eccentricity of 0.52 and an inclination to the ecliptic of 15.6 degrees. At perihelion, it moves much closer to the Sun than Uranus, while at aphelion it moves out well beyond the orbit of Neptune.
The orbits of centaurs are unstable due to perturbations by the giant planets. Nessus is a SE object since currently Saturn controls the perihelion and the Edgeworth–Kuiper belt controls the aphelion.[5] Nessus is estimated to have a relatively long orbital half-life of about 4.9 Myr.[5] Fifty clones of the orbit of Nessus suggest that Nessus will not pass within 1AU (150Gm) of a planet for at least twenty thousand years.[6]
The naming of Nessus is an interesting break from tradition. Three astrologers were independently studying 1993 HA2 to see if it had any astrological significance. These were Zane B. Stein in the USA, and Dieter Koch and Robert Von Heeren in Germany. In separate letters to astronomers David L. Rabinowitz, Alan Stern, Jim Scotti and Dr. Brian Marsden, these astrologers suggested naming the body after the mythological centaur Nessus.
Dr. Marsden gave his support to the suggested name, and recommended it to the IAU. This name was approved, and 1993 HA2 was officially named 7066 Nessus on April 22, 1997. This naming was an unprecedented cooperation between astrologers and astronomers.
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