Discovery | |
---|---|
Discovered by | G. Schiaparelli |
Discovery date | April 29, 1861 [1] |
Designations | |
(69) Hesperia | |
Pronunciation | /hɛˈspɪəriə/ [2] |
Named after | Hesperia |
Main belt | |
Adjectives | Hesperian /hɛˈspɪəriən/ [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)×1018 kg [6] |
Mean
density | 4.38±0.99 g/cm3 [6] |
5.655 h [4] | |
0.140 [4] | |
M | |
7.05 [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]