Origin and Evolution
Ceres is probably a surviving protoplanet (planetary embryo), which formed 4.57 billion years ago in the asteroid belt. While the majority of inner Solar System protoplanets (including all lunar- to Mars-sized bodies) either merged with other protoplanets to form terrestrial planets or were ejected from the Solar System by Jupiter, Ceres is believed to have survived relatively intact. An alternative theory proposes that Ceres formed in the Kuiper belt and later migrated to the asteroid belt. Another possible protoplanet, Vesta, is less than half the size of Ceres; it suffered a major impact after solidifying, losing ~1% of its mass.
The geological evolution of Ceres was dependent on the heat sources available during and after its formation: friction from planetesimal accretion, and decay of various radionuclides (possibly including short-lived elements like 26Al). These are thought to have been sufficient to allow Ceres to differentiate into a rocky core and icy mantle soon after its formation. This process may have caused resurfacing by water volcanism and tectonics, erasing older geological features. Due to its small size, Ceres would have cooled early in its existence, causing all geological resurfacing processes to cease. Any ice on the surface would have gradually sublimated, leaving behind various hydrated minerals like clays and carbonates.
Today, Ceres appears to be a geologically inactive body, with a surface sculpted only by impacts. The presence of significant amounts of water ice in its composition raises the possibility that Ceres has or had a layer of liquid water in its interior. This hypothetical layer is often called an ocean. If such a layer of liquid water exists, it is believed to be located between the rocky core and ice mantle like that of the theorized ocean on Europa. The existence of an ocean is more likely if solutes (i.e. salts), ammonia, sulfuric acid or other antifreeze compounds are dissolved in the water.
Read more about this topic: Ceres (dwarf Planet)
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