69 Hesperia
Main-belt asteroid
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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.
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A three-dimensional model of 69 Hesperia based on its light curve. | |
| Discovery | |
|---|---|
| Discovered by | G. Schiaparelli |
| Discovery date | April 29, 1861[1] |
| Designations | |
| (69) Hesperia | |
| Pronunciation | /hÉËspɪÉriÉ/[2] |
Named after | Hesperia |
| Main belt | |
| Adjectives | Hesperian /hÉËspɪÉriÉn/[3] |
| Orbital characteristics | |
| Epoch (absent) | |
| Aphelion | 3.471 AU (519.3 Gm) |
| Perihelion | 2.489 AU (372.3 Gm) |
| 2.980 AU (445.8 Gm) | |
| Eccentricity | 0.165 |
| 1,879 days (5.14 a) | |
| Inclination | 8.59° |
| 184.99° | |
| 288.8° | |
| Physical characteristics | |
| Dimensions | 138 km (IRAS)[4] 110 ± 15 km[5] |
| Mass | (5.86±1.18)Ã1018 kg[6] |
Mean density | 4.38±0.99 g/cm3[6] |
| 5.655 h[4] | |
| 0.140[4] | |
| M | |
| 7.05[4] | |
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]
