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Answer: Ceres is a dwarf planet and the largest object in the asteroid belt between Mars and Jupiter. It is the only dwarf planet in the inner solar system, and it was the first dwarf planet to be orbited by a spacecraft, NASA's Dawn.

Key facts

• Discovery: Ceres was the first member of the asteroid belt to be discovered, when Giuseppe Piazzi spotted it in 1801.
• Reclassified: called an asteroid for many years, Ceres is so much bigger and so different from its rocky neighbors that scientists classified it as a dwarf planet in 2006.
• Mass: Ceres comprises 25% of the asteroid belt's total mass, yet Pluto is still 14 times more massive.
• Size: with a radius of 296 miles (476 kilometers), Ceres is 1/13 the radius of Earth. If Earth were the size of a nickel, Ceres would be about as big as a poppy seed.
• Distance: from an average distance of 257 million miles (413 million kilometers), Ceres is 2.8 astronomical units from the Sun. Sunlight takes 22 minutes to travel from the Sun to Ceres.
• Name: Ceres is named for the Roman goddess of corn and harvests. The word cereal comes from the same name.

Dawn's visit

Dawn launched on Sept. 27, 2007. It went into orbit around Ceres on March 6, 2015, about four months before New Horizons flew past Pluto on July 14, 2015.

Claims

• id: C1 claim: Ceres is the only dwarf planet in the inner solar system. source: S1 evidence: "Ceres is the only dwarf planet in the inner solar system."
• id: C2 claim: Ceres was the first dwarf planet orbited by a spacecraft. source: S1 evidence: "Ceres was the first dwarf planet to be orbited by a spacecraft."
• id: C3 claim: Ceres is named for the Roman goddess of corn and harvests. source: S2 evidence: "Ceres is named for the Roman goddess of corn and harvests."

Sources

• [S1] Ceres. NASA. https://science.nasa.gov/dwarf-planets/ceres/ . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Ceres: Facts. NASA. https://science.nasa.gov/dwarf-planets/ceres/facts/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_8b0ca70w,
  author = {{iinventedlight}},
  title = {{Ceres: the dwarf planet in the asteroid belt}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/ceres-dwarf-planet/},
  note = {Permanent ID iil:note:8b0ca70w. License: CC-BY-4.0.},
}

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