Ceres

Dwarf Planet· orbits the Sun

Ceres is the largest object in the asteroid belt and the only dwarf planet in the inner Solar System. It is rich in water ice and bright salt deposits, studied in detail by NASA's Dawn mission.

Open in 3D viewSee Ceres in the live, interactive 3D map

Key facts

Mass

9.38 × 10²⁰ kg

0.0128 Moon masses

Radius

470 km

7% of Earth's radius

Surface gravity

0.284 m/s²

3% of Earth's gravity

Day length

9.07 hours

Year

4.6 Earth years

1,680 Earth days

Distance from Sun

2.77 AU

Moons

None

Science

Physical

Mass: 9.38 × 10²⁰ kg · 0.0128 Moon masses
Radius: 470 km · 7% of Earth's radius
Density: 2,162 kg/m³ · 2.2× water; Computed from mass and radius
Surface gravity: 0.284 m/s² · 3% of Earth's gravity; Computed from mass and radius
Escape velocity: 516 m/s · 5% of Earth's escape velocity; Computed from mass and radius
Axial tilt: 4.00 °

Orbital

Distance from the Sun: 2.66 AU; Computed from the position at the selected time
Semi-major axis: 2.77 AU; Computed from the cached state vector
Eccentricity: 0.07979; Computed from the cached state vector
Inclination: 27.19 °; Computed from the cached state vector
Orbital period: 4.60 years; Computed from the cached state vector
Perihelion: 2.55 AU; Computed from the orbital elements
Aphelion: 2.99 AU; Computed from the orbital elements
Mean orbital velocity: 17.9 km/s; Computed from the orbital elements

Rotation

Rotation period: 9.07 hours

Temperature

Mean: 168 K (-105 °C)

Composition

Bulk composition: Rocky core with a water-ice-rich mantle and salt deposits

Radiation & temperature

Insolation: 0.131 S⊕ · 13% of the sunlight Earth receives; Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
Bond albedo: 0.09 · reflects 9% of incoming sunlight
Equilibrium temperature: 163 K (-110 °C); Computed from albedo + distance from the Sun (airless black body)
Measured mean temperature: 168 K (-105 °C)

Discovery & history

Discovered: January 1, 1801
By: Giuseppe Piazzi
Method: Visual discovery (telescopic)
Name: The Roman goddess of agriculture and patron of Sicily, where it was found.

Ceres was discovered on the first night of the 19th century, 1 January 1801, by Giuseppe Piazzi in Palermo. Hailed as a new planet filling the 'gap' between Mars and Jupiter, it was soon joined by Pallas, Juno and Vesta, and the four were reclassified as 'asteroids'. Ceres is by far the largest, and in 2006 it was promoted to dwarf planet. The Dawn spacecraft orbited it in 2015.