69 Hesperia

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.

69 Hesperia

A three-dimensional model of 69 Hesperia based on its light curve.
Discovery
Discovered by	G. Schiaparelli
Discovery date	April 29, 1861[1]
Designations
MPC designation	(69) Hesperia
Pronunciation	/hɛˈspɪəriə/[2]
Named after	Hesperia
Minor planet category	Main belt
Adjectives	Hesperian /hɛˈspɪəriən/[3]
Orbital characteristics
Epoch (absent)
Aphelion	3.471 AU (519.3 Gm)
Perihelion	2.489 AU (372.3 Gm)
Semi-major axis	2.980 AU (445.8 Gm)
Eccentricity	0.165
Orbital period (sidereal)	1,879 days (5.14 a)
Inclination	8.59°
Longitude of ascending node	184.99°
Argument of perihelion	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]
Synodic rotation period	5.655 h[4]
Geometric albedo	0.140[4]
Spectral type	M
Absolute magnitude (H)	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]