10 Hygiea
Asteroid· orbits the Sun
Hygiea is the fourth-largest asteroid — a dark, carbon-rich (C-type) body that is nearly spherical, making it a possible dwarf-planet candidate.
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Key facts
Radius
215 km
3% of Earth's radius
Distance from Sun
3.15 AU
Orbital period
5.59 years
Eccentricity
0.1067
Rotation
13.83 hours
Science
Physical
- Mean radius
- 215 km · 3% of Earth's radius
- Mass
- 1.05 × 10²⁰ kg · 0.00143 Moon masses
- Density
- 2,519 kg/m³ · 2.5× water
- Rotation period
- 13.83 hours
Orbital
- Semi-major axis
- 3.15 AU
- Eccentricity
- 0.1067
- Inclination
- 3.83 °
- Orbital period
- 5.59 years
- Perihelion
- 2.81 AU
- Aphelion
- 3.49 AU
- Mean orbital velocity
- 16.8 km/s
Discovery
- Discovered
- April 12, 1849
- Discoverer
- Annibale de Gasparis
Composition
- Make-up
- A dark, carbonaceous (C-type) body of hydrated minerals; round enough to be a dwarf-planet candidate.
Radiation & temperature
- Insolation
- 0.101 S⊕ · 10% of the sunlight Earth receives
- Geometric albedo
- 0.07
- Equilibrium temperature
- 154 K (-119 °C)
Discovery & history
- Discovered
- April 12, 1849
- By
- Annibale de Gasparis
- Method
- Visual discovery (telescopic)
- Name
- Hygieia, the Greek goddess of health — the root of the word 'hygiene'.
Hygiea, found by Annibale de Gasparis in 1849, is the fourth-largest asteroid and the largest of the dark, carbon-rich 'C-type' bodies of the outer belt. Images in 2019 suggest it is nearly spherical, which could make it the smallest dwarf planet — but it has never been visited, and its true shape remains uncertain.
Images
Images from open archives · credit shown per image