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]
(69) Hesperia
Named after
Main belt
AdjectivesHesperian /hɛˈspɪəriən/[3]
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)[4]
110 ± 15 km[5]
Mass(5.86±1.18)×1018 kg[6]
Mean density
4.38±0.99 g/cm3[6]
5.655 h[4]

Hesperia (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, while he was searching for the recently discovered 63 Ausonia.[7] It was his only asteroid discovery. Schiaparelli named it Hesperia in honour of Italy (the word is a Greek term for the peninsula).[8] The asteroid is orbiting the Sun with a period of 5.14 years, a semimajor axis of 2.980 AU, and eccentricity of 0.165. The orbital plane is inclined by an angle of 8.59° to the plane of the ecliptic.

Hesperia was observed by Arecibo radar in February 2010.[5] Radar observations combined with lightcurve-based shape models, lead to a diameter estimate of 110 ± 15 km (68 ± 9.3 mi). The radar albedo is consistent with a high-metal M-type asteroid.[5] In the near infrared, a weak absorption feature near a wavelength of 0.9 μm can be attributed to orthopyroxenes on the surface.[9] A meteorite analogue of the reflectance spectra from 69 Hesperia is the Hoba ataxite.[10]


  1. ^ a b "Editorial Notice" (PDF). The Minor Planet Circulars. MPC 94743-95312: 94743. 29 August 2015. Retrieved 4 September 2015.
  2. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  3. ^ "Hesperian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  4. ^ a b c d "JPL Small-Body Database Browser: 69 Hesperia" (2011-09-07 last obs). Jet Propulsion Laboratory. Retrieved 27 January 2012.
  5. ^ a b c 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. arXiv:1104.4114. Bibcode:2011Icar..215..547S. doi:10.1016/j.icarus.2011.07.027.
  6. ^ a b Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  7. ^ De Meis, S. (2011), "A few aspects of Schiaparelli's studies", Memorie della Societa Astronomica Italiana, 82: 290, Bibcode:2011MmSAI..82..290D.
  8. ^ Schmadel, Lutz D. (2003), Dictionary of Minor Planet Names, Springer Science & Business Media, p. 22, ISBN 978-3-540-00238-3.
  9. ^ 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.
  10. ^ 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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