2101 Adonis


2101 Adonis, provisional designation: 1936 CA, is an asteroid on an extremely eccentric orbit, classified as potentially hazardous asteroid and near-Earth object of the Apollo group. Adonis measures approximately 1 kilometer (0.6 miles) in diameter. Discovered by Eugène Delporte at Uccle in 1936, it became a lost asteroid until 1977. It may also be an extinct comet and a source of meteor showers.[6] It was named after Adonis from Greek mythology.[3]

2101 Adonis
Discovered byE. Delporte
Discovery siteUccle Obs.
Discovery date12 February 1936
(2101) Adonis
Pronunciation/əˈdnɪs/,[2] or
/əˈdɒnɪs/ (NAE)
Named after
(Greek mythology)[3]
1936 CA
NEO · PHA · Apollo[1][4]
Orbital characteristics[4]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc82.16 yr (30,009 d)
Aphelion3.3069 AU
Perihelion0.4415 AU
1.8742 AU
2.57 yr (937 d)
0° 23m 2.76s / day
Earth MOID0.0116 AU (4.52 LD)
Physical characteristics



Adonis was discovered on 12 February 1936, by Belgian astronomer Eugène Delporte at the Royal Observatory of Belgium in Uccle.[1] After its initial discovery, which happened during a close approach with Earth, the asteroid was observed for two months, before it became a lost asteroid, as not enough observations could be made to calculate a sufficiently accurate orbit. It took 41 years until it was finally rediscovered by the American astronomer Charles Kowal in 1977, based on mathematical predictions made by Dr. Brian Marsden.[7]

Orbit and classification


The near-Earth object orbits the Sun at a distance of 0.4–3.3 AU once every 2 years and 7 months (937 days; semi-major axis of 1.87 AU). Its orbit has an eccentricity of 0.76 and an inclination of 1° with respect to the ecliptic.[4]

Adonis was one of the first near-Earth objects ever to be discovered. It was also the second known Apollo asteroid after 1862 Apollo, the group's namesake discovered four years earlier in 1932.



It is a potentially hazardous asteroid because its Earth minimum orbit intersection distance of 1.74 million km (0.0116 AU), or 4.5 lunar distances, is less than 0.05 AU and its diameter is greater than 150 meters. It also makes close approaches to Venus and Mars and will come within 30 Gm of the Earth six times during the 21st century, the nearest projected distance being 5.34 million km (0.03569 AU), on 7 February 2036.[4][8][9]



This minor planet is named from Greek mythology after the handsome, ever-youthful vegetation god Adonis, with whom the goddess Aphrodite fell in love. Persephone was also taken by Adonis' beauty and refused to give him back to Aphrodite. The dispute between the two goddesses was settled by Zeus: Adonis was to spend one-third of every year with each goddess and the last third wherever he chose. He was killed by a boar sent by Artemis. The minor planets 105 Artemis, 399 Persephone, 1388 Aphrodite and 5731 Zeus were named for these Greek gods.[3] The official naming citation was published by the Minor Planet Center on 1 November 1978 (M.P.C. 4548).[10]

Physical characteristics


Adonis has an absolute magnitude of 18.8, and an estimated mean diameter between 520 and 600 meters.[4][5] As of 2017, the body's rotation period, composition, spectral type and shape remain unknown.[4][11]



A famous Tintin book shows this asteroid too near from the Earth but Adonis was considered as a possible target for a 6 million km distant flyby by the Vega 2 spacecraft after its 1986 flyby of Halley's Comet. In the event Vega 2 didn't have enough fuel post Halley encounter to make the necessary orbital changes for the flyby.[12]


  1. ^ a b c d "2101 Adonis (1936 CA)". Minor Planet Center. Retrieved 17 October 2019.
  2. ^ "Adonis". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ a b c Schmadel, Lutz D. (2007). "(2101) Adonis". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 170. doi:10.1007/978-3-540-29925-7_2102. ISBN 978-3-540-00238-3.
  4. ^ a b c d e f g h "JPL Small-Body Database Browser: 2101 Adonis (1936 CA)" (2018-04-11 last obs.). Jet Propulsion Laboratory. Retrieved 17 October 2019.
  5. ^ a b "(2101) Adonis – PHYSICAL INFORMATION". NEODyS—Near Earth Objects – Dynamic Site. Archived from the original on 6 October 2016. Retrieved 17 October 2019.
  6. ^ Babadzhanov, P. B. (2003). "Meteor showers associated with the near-Earth asteroid (2101) Adonis". Astronomy and Astrophysics. 397 (1): 319–323. Bibcode:2003A&A...397..319B. doi:10.1051/0004-6361:20021506.
  7. ^ "Brian Marsden, Tracker of Comets, Dies at 73". The New York Times. Retrieved 22 November 2010.
  8. ^ "JPL Close-Approach Data: 2101 Adonis (1936 CA)" (2008-03-10 last obs.). Retrieved 5 May 2009.
  9. ^ "NEODys-2 (2101) Adonis". Department of Mathematics, University of Pisa. Retrieved 17 October 2019.
  10. ^ Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.
  11. ^ "LCDB Data for (2101) Adonis". Asteroid Lightcurve Database (LCDB). Retrieved 11 June 2017.
  12. ^ Ulivi, Paolo; Harland, David M (2009). Robotic Exploration of the Solar System Part 2 Hiatus and Renewal. Praxis Publishing. pp. 90–92. ISBN 9780387789040.
  • Long-lost planet 1936 CA ("Adonis") recovered
  • Benner, et al. - Radar Detection of Near-Earth Asteroids 2062 Aten, 2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN (1997)
  • Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
  • Dictionary of Minor Planet Names, Google books
  • Discovery Circumstances: Numbered Minor Planets (1)–(5000) – Minor Planet Center
  • 2101 Adonis at NeoDyS-2, Near Earth Objects—Dynamic Site
    • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
  • 2101 Adonis at the JPL Small-Body Database  
    • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters