Ceres is a dwarf planet in the main asteroid belt between the orbits of Mars and Jupiter. It was the first object identified in the asteroid belt, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily, and announced as a new planet. Ceres was later classified as an asteroid, and then more recently as the only confirmed dwarf planet within the asteroid belt, and the largest without a moon. It is also the only recognized dwarf planet in the solar system whose orbit lies within that of Neptune.
Facts
Object TypeDwarf planet (IAU classification, 2006, asteroid belt); planet (1801 classification) 1 Classified a planet at discovery in 1801, then an asteroid once similar bodies were found nearby, then a dwarf planet under the IAU's 2006 dynamical definition; a minority of planetary scientists, including New Horizons principal investigator Alan Stern, reject that dynamical definition in favor of a geophysical one that would restore Ceres to full planet status. See the recorded dissent on this fact. Diameter (km) Orbital Distance2.77 AU (about 414 million km from the Sun) 1 Discovery Year Connections
Associated With
Pluto, Celestial Objects Why this is disputed. Both bodies were reclassified as dwarf planets under the IAU's 2006 dynamical definition of planet, a classification a minority of planetary scientists dispute in favor of a geophysical definition; see the recorded dissent on Ceres's object-type.
Source Wikipedia (space and spaceflight articles)
Orbits
Sun, Celestial Objects Ceres orbits the Sun within the main asteroid belt between Mars and Jupiter.
Sources
1. Wikipedia: Ceres (dwarf planet)
Lead sectionQuote, Lead section
It was the first object identified in the asteroid belt, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily, and announced as a new planet.
Wikipedia (space and spaceflight articles)
Wikimedia FoundationCeres dwarf planet (Wikipedia) - dwarf planet classification
Bodies that met the first proposed definition but not the second, such as Ceres, were instead classified as dwarf planets.
Ceres dwarf planet (Wikipedia) - diameter
approximately 939 km (583.7 miles)
Ceres (dwarf planet), Wikipedia - physical characteristics infobox
approximately 9.38392 x 10^20 kg
Ceres (dwarf planet), Wikipedia - orbital characteristics infobox
2.77 AU (414 million km)
Ceres (dwarf planet), Wikipedia - lead section respelling
SEER-eez
Entity description, ceres-dwarf-planet catalogue classification
The largest object in the asteroid belt between Mars and Jupiter, discovered on 1 January 1801 by Giuseppe Piazzi and originally classified as a planet, then as an asteroid once similar bodies were found nearby.
Associated With: Pluto, Dwarf planet (Wikipedia) - Ceres and Pluto pairing
such as Ceres, were instead classified as dwarf planets
View the Source NASA Solar System Exploration
National Aeronautics and Space AdministrationCeres Facts, Introduction section, asteroid belt sentence
Dwarf planet Ceres is the largest object in the asteroid belt between Mars and Jupiter, and it's the only dwarf planet located in the inner solar system.
Ceres Facts, Introduction section, Dawn sentence
When NASA's Dawn arrived in 2015, Ceres became the first dwarf planet to receive a visit from a spacecraft.
Ceres Facts, Orbit and Rotation section, orbital period sentence
Ceres takes 1,682 Earth days, or 4.6 Earth years, to make one trip around the Sun.
Ceres Facts, Introduction section, discovery sentence
It was the first member of the asteroid belt to be discovered when Giuseppe Piazzi spotted it in 1801.
Ceres Facts, Namesake section
Ceres is named for the Roman goddess of corn and harvests.
Ceres Facts, Orbit and Rotation section, rotation sentence
As Ceres orbits the Sun, it completes one rotation every 9 hours, making its day length one of the shortest in the solar system.
Ceres Facts, Structure section, core and mantle sentence
Ceres probably has a solid core and a mantle made of water ice.
Ceres Facts, Atmosphere section, thin atmosphere sentence
Ceres has a very thin atmosphere, and there is evidence it contains water vapor.
View the Source Dissenting Readings (1 dissenting reading)
Object Type
The IAU's 2006 dynamical definition of planet requires a body to have gravitationally cleared its orbital neighborhood, which excludes Ceres, Pluto and other dwarf planets. A minority of planetary scientists, prominently New Horizons principal investigator Alan Stern, reject this dynamical test and argue for a geophysical definition based on a body's intrinsic roundness (hydrostatic equilibrium) instead of its orbital surroundings; under that definition Ceres, Pluto and other dwarf planets would count as full planets. The IAU's definition remains the operative classification used by this atlas, but the dispute is unresolved among working planetary scientists.
A dissenting reading, from an independent laneWikipedia (space and spaceflight articles), Wikimedia Foundation
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