69 Hesperia

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69 Hesperia
69Hesperia (Lightcurve Inversion).png
A three-dimensional model of 69 Hesperia based on its light curve.
Discovered byG. Schiaparelli
Discovery dateApril 29, 1861[1]
MPC designation(69) Hesperia
Named after
Main belt
Orbital characteristics
Epoch (absent)
Aphelion3.471 AU (519.3 Gm)
Perihelion2.489 AU (372.3 Gm)
2.980 AU (445.8 Gm)
1,879 days (5.14 a)
Physical characteristics
Dimensions138 km (IRAS)[2]
135x106x98 km[3]
110 ± 15 km[3]
Mass(5.86±1.18)×1018 kg[4]
Mean density
4.38±0.99 g/cm3[4]
5.655 h[2]

Hesperia (/hɛsˈpɪəriə/ hes-PEER-ee-ə; minor planet designation: 69 Hesperia) is a large, M-type main-belt asteroid. It was discovered by the Italian astronomer Giovanni Schiaparelli on April 29, 1861[1] from Milan. It was his only asteroid discovery. Schiaparelli named it Hesperia in honour of Italy (the word is a Greek term for the peninsula).[5]

Hesperia was observed by Arecibo radar in February 2010.[3] Radar observations combined with lightcurve-based shape models, lead to a diameter estimate of 110 ± 15 km (68 ± 9.3 mi).[3] In the near infrared, a weak absorption feature near a wavelength of 0.9 μm can be attributed to orthopyroxenes on the surface.[6] A meteorite analogue of the reflectance spectra from 69 Hesperia is the Hoba ataxite.[7]


  1. ^ a b "Editorial Notice" (PDF). The Minor Planet Circulars. MPC 94743-95312: 94743. 29 August 2015. Retrieved 4 September 2015.
  2. ^ a b c d "JPL Small-Body Database Browser: 69 Hesperia" (2011-09-07 last obs). Jet Propulsion Laboratory. Retrieved 27 January 2012.
  3. ^ a b c d Shepard, Michael K.; Harris, Alan W.; Taylor, Patrick A.; Clark, Beth Ellen; Ockert-Bell, Maureen; Nolan, Michael C.; et al. (2011). "Radar observations of Asteroids 64 Angelina and 69 Hesperia" (PDF). Icarus. 215 (2): 547–551. Bibcode:2011Icar..215..547S. doi:10.1016/j.icarus.2011.07.027.
  4. ^ a b Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  5. ^ Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names. Springer Science & Business Media. p. 22. ISBN 978-3-540-00238-3.
  6. ^ Hardersen, Paul S.; et al. (May 2005), "Near-IR spectral evidence for the presence of iron-poor orthopyroxenes on the surfaces of six M-type asteroids", Icarus, 175 (1): 141−158, Bibcode:2005Icar..175..141H, doi:10.1016/j.icarus.2004.10.017.
  7. ^ Neeley, J. R.; et al. (August 2014), "The composition of M-type asteroids II: Synthesis of spectroscopic and radar observations", Icarus, 238: 37−50, arXiv:1407.0750, Bibcode:2014Icar..238...37N, doi:10.1016/j.icarus.2014.05.008.

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