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Ceres (dwarf planet) facts for kids

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Ceres Ceres symbol.svg
Discovered by Giuseppe Piazzi
Discovery date January 1, 1801
MPC designation 1 Ceres
A899 OF; 1943 XB
dwarf planet
main belt
Orbital characteristics
Epoch November 26, 2005
(JD 2453700.5)
Aphelion 447,838,164 km
2.987 AU
Perihelion 381,419,582 km
2.544 AU
414,703,838 km
2.765 956 424 AU
Eccentricity 0.07976017
1679.819 days
4.599 years
17.882 km/s
Inclination 10.586712°
Physical characteristics
Mean radius
473 km
Flattening 0.067 ± 0.005
Mass 9.46 ± 0.04×1020 kg
Mean density
2.08 g/cm3
Equatorial surface gravity
0.27 m/s²
0.028 g
Equatorial escape velocity
0.51 km/s
0.3781 d
9.074 h
0.113 (geometric)
Surface temp. min mean max
Kelvin ~167 K 239 K
6.7 to 9.32
Angular diameter
0.84" to 0.33"

Ceres, also known as 1 Ceres, is a dwarf planet in the Solar System. It is located in the middle main asteroid belt between the orbits of Mars and Jupiter.

Ceres was discovered on 1 January 1801, by Giuseppe Piazzi, and is named after the Roman goddess Ceres, as the goddess of growing plants, the harvest, and of motherly love. After about 200 years from its discovery, the International Astronomical Union decided to upgrade Ceres from an asteroid (or minor planet) to dwarf planetary status in 2006.

With a diameter of about 950 km, Ceres is by far the largest and most massive object in the asteroid belt, and has about a third of the belt's total mass. It was once thought to be smaller than Vesta, which is brighter.

Ceres's small size means that even at its brightest, it is too dim to be seen by the naked eye, except under extremely dark skies. As a result, its surface features are barely visible even with the most powerful telescopes, and little was known about it until the robotic NASA spacecraft Dawn approached Ceres for its orbital mission in 2015.

PIA20353 Ceres Neutron Counts Reflect Hydrogen Abundance (cropped)
Hydrogen concentration (blue) in the upper metre of the regolith indicating presence of water ice

Dawn found Ceres's surface to be a mixture of water ice and hydrated minerals such as carbonates and clay. Gravity data suggest Ceres to be partially differentiated into a muddy (ice-rock) mantle/core and a less dense but stronger crust that is at most thirty percent ice by volume. Although Ceres likely lacks an internal ocean of liquid water, brines still flow through the outer mantle and reach the surface, allowing cryovolcanoes such as Ahuna Mons to form roughly every fifty million years.

Ceres has an unusual crater, Occator which contains bright salts.


Ceres follows an orbit between Mars and Jupiter, near the middle of the asteroid belt, with an orbital period (year) of 4.6 Earth years. Compared to other planets and dwarf planets, Ceres's orbit is moderately tilted relative to that of Earth.


Ceres is the largest asteroid in the main asteroid belt. Measurements from the Dawn spacecraft found a mean diameter of 939.4 km (583.7 mi) and a mass of 9.38×1020 kg. This gives Ceres a density of 2.16 g/cm3, suggesting that a quarter of its mass is water ice.

Ceres comprises 40% of the estimated (2394±5)×1018 kg mass of the asteroid belt, and it has 31 times the mass of the next asteroid, Vesta, but it is only 1.3% the mass of the Moon.


Studies using the Hubble Space Telescope show graphite, sulfur, and sulfur dioxide on Ceres's surface.


Dawn revealed that Ceres has a heavily cratered surface, though with fewer large craters than expected.

Ceres's north polar region shows far more cratering than the equatorial region.


In 2017, Dawn confirmed that Ceres has a transient atmosphere of water vapour.

Origin and evolution

Ceres is a surviving protoplanet that formed 4.56 billion years ago; alongside Pallas and Vesta, one of only three remaining in the inner Solar System, with the rest either merging to form terrestrial planets, being shattered in collisions or being ejected by Jupiter.


Although Ceres is not as actively discussed as a potential home for microbial extraterrestrial life as Mars, Europa, Enceladus, or Titan are, it has the most water of any body in the inner Solar System after Earth, and the likely brine pockets under its surface could provide habitats for life.

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See also

Kids robot.svg In Spanish: Ceres (planeta enano) para niños

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