Ceres

Once considered a planet, this asteroid has enough mass to be spherical. Later designated a dwarf planet, learn more about Ceres here!

Formation

The asteroid belt is located between Mars and Jupiter, and is the home of the dwarf planet Ceres. Chemical analysis of the asteroids and Ceres shows that Ceres likely formed further out between Jupiter and Saturn. Since Jupiter is expected to have migrated out towards the present position of Jupiter from the inner Solar System, the gravitational influence of Jupiter probably pushed Ceres inwards to the asteroid belt.

Composition

The surface of Ceres is mostly carbonates and silicates. There is also water ice on the poles, though the equatorial region is relatively ice free. The surface of Ceres is covered in craters, consistent with the number expected from the late heavy bombardment era. However, Ceres does not have as many large craters as predicted. This is attributed to the surface being shifted in the early period of the formation of Ceres through cryovolcanism.

Structure

The structure of Ceres is under debate. Some models suggest that Ceres has three layers, a core, mantle, and crust. Other models suggest that Ceres only has two layers, the core and mantle, and a small layer of crust at the surface, only tens of meters thick. In both models, the mantle consists of a hydrated rock mixture composed of water and silicates.

Atmosphere

Ceres was confirmed to have a tenuous atmosphere of water vapor, produced through the sublimation of surface water ice in direct solar rays. This exosphere is losing water vapor particles to space and has shown to accelerate electrons streaming towards Ceres.

Satellites

Ceres has been visited by the Dawn spacecraft, imaging its surface, and collecting gravitational data. Dawn also confirmed that Ceres has an exosphere of water vapor. During the mission features on the surface were studied in detail, with mountains and craters used to help determine the origins and evolution of Ceres.