Changes

{{Planet|image=Ceres.jpg

{{Planet|image=Ceres.jpg

|date=January 1, 1801

|date=January 1, 1801<ref name=gazette>Blue, Jennifer, ed. "[http://planetarynames.wr.usgs.gov/append7.html#DwarfPlanets Gazetteer of Planetary Nomenclature: Planetary Body Names and Discoverers]." [[United States Geological Survey]], March 31, 2008. Accessed June 2, 2008.</ref>

|discname=Giuseppe Piazzi

|origname=Roman goddess of agriculture

|discname=Giuseppe Piazzi<ref name=gazette/>

|origname=Roman goddess of agriculture<ref name=gazette/>

|primary=Sun

|primary=Sun

|order=5

|order=5

|periapsis=2.545 AU

|periapsis=2.54670746 AU<ref name=ssdelem>"[http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Ceres;orb=1 Orbital elements for 1 Ceres]." JPL Small-Body Database, [[Jet Propulsion Laboratory|JPL]], [[National Aeronautics and Space Administration|NASA]], May 14, 2008. Accessed June 2, 2008.</ref>

|apoapsis=2.987 AU

|apoapsis=2.986856037 AU<ref name=ssdelem/>

|semimajor=2.765956424 AU

|semimajor=2.76678175 AU<ref name=ssdelem/>

|bode=2.8 AU

|bode=2.8 AU

|eccentricity=0.07976017

|eccentricity=0.07954162<ref name=ssdelem/>

|sidereal=4.599 a

|sidereal=1680.973163 da<ref name=ssdelem/>

|orbitspeed=17.882 km/s

|orbitspeed=17.882 km/s

|inclination=10.586712°

|inclination=10.586404°<ref name=ssdelem/>

|reference=the ecliptic

|reference=the ecliptic

|siderealday=9.074 h (0.378 da)

|siderealday=9.075 h<ref name=ssdelem/>

|rotatespeed=0.091584 m/s<ref name=ssdelem/>

|axialtilt=3°

|axialtilt=3°

|mass=9.46 * 10²⁰ kg (0.0158% earth)

|mass=9.47 * 10²⁰ kg<ref name=calc>Calculated</ref>

|density=2,077 kg/m³

|density=2,093.95 kg/m³<ref name=calc/>

|surfacegrav=0.27 m/s² (0.0275 ''g'')

|surfacegrav=0.2787 m/s²<ref name=calc/>

|escapespeed= 0.51 km/s

|escapespeed= 0.5152 km/s<ref name=calc/>

|equatorradius=487.3 km

|equatorradius=487.3 km

|polarradius=454.7 km

|polarradius=454.7 km

|surfacearea= 21,237,000 km² (4.164% earth)

|surfacearea= 2,849,631 km²<ref name=calc/>

|meantemp=167 K

|meantemp=167 K

|maxtemp=239 K

|maxtemp=239 K

|moons=none known

|moons=0

}}'''Ceres''' is the largest planetoid and the first identified object in the [[Asteroid Belt]], roughly one-fourth of the diameter of the [[Moon]]. Giuseppe Piazzi discovered it on January 1, 1801. Recently, in the wake of the [[Eris]]-[[Pluto]] controversy, the [[International Astronomical Union]] has declared that it is more than a mere asteroid and qualifies as a [[dwarf planet]].

}}'''Ceres''', formerly known as '''Asteroid 1 Ceres''', is the largest planetoid and the first identified object in the [[Asteroid Belt]], roughly one-fourth of the diameter of the [[Moon]]. Giuseppe Piazzi discovered it on January 1, 1801. Recently, in the wake of the [[Eris]]-[[Pluto]] controversy, the [[International Astronomical Union]] has declared that it is more than a mere asteroid and qualifies as a [[dwarf planet]].

Ceres is named for the Roman goddess of agriculture, from which name the word ''cereal'' derives.

Ceres is named for the Roman goddess of agriculture, from which name the word ''cereal'' derives.

== Composition ==

== Composition ==

Recent observations made by the Hubble Space Telescope suggest that Ceres might be very rich in [[water]] ice. Specifically, astronomers have concluded that Ceres has a layered interior, with a rocky inner core, a thick layer of water ice, and a dusty outer crust. McFadden specifically says that Ceres is an "embryonic planet," one that (according to evolutionary theory) tried to form a planet but could not because [[Jupiter]], being so close, so perturbed the local gravitational field that Ceres could not grow any larger than it is. Findings supporting the water-ice theory include:

Recent observations made by the Hubble Space Telescope suggest that Ceres might be very rich in [[water]] ice. Specifically, astronomers have concluded that Ceres has a layered interior, with a rocky inner core, a thick layer of water ice, and a dusty outer crust. McFadden specifically says that Ceres is an "embryonic planet," one that (according to evolutionary theory) tried to form a planet but could not because [[Jupiter]], being so close, so perturbed the local gravitational field that Ceres could not grow any larger than it is.<ref>Carey, Bjorn. "[http://www.space.com/scienceastronomy/050907_ceres_planet.html Largest Asteroid Might Contain More Fresh Water than Earth]." ''Space.com'', September 7, 2005. Accessed January 22, 2008.</ref><ref>"[http://planetary.org/explore/topics/asteroids_and_comets/ceres.html Asteroid 1 Ceres]." ''The Planetary Society''. Accessed January 22, 2008.</ref> Findings supporting the water-ice theory include:

# Most objects having hydrostatic-equilibrium or round shape have differentiated, or layered, interiors.

# Most objects having hydrostatic-equilibrium or round shape have differentiated, or layered, interiors.

# Spectrography of the surface shows evidence of water-bearing minerals.

# Spectrography of the surface shows evidence of water-bearing minerals.

Parker and his colleagues speculate that Ceres might be composed of 25% water and thus have more fresh water than in all the fresh-water sources on [[earth]].

Parker and his colleagues speculate that Ceres might be composed of 25% water and thus have more fresh water than in all the fresh-water sources on [[earth]].<ref>Parker, Joel William, Thomas, Peter C., McFadden, Lucy A., Mutchler, M., and Levay, Z. "[http://hubblesite.org/newscenter/archive/releases/2005/27/ Largest Asteroid May Be 'Mini-Planet' with Water Ice]." ''The Hubble Site'', September 7, 2005. Accessed January 22, 2008.</ref>

== Satellites ==

== Satellites ==

Ceres has no known satellites at present.

Ceres has no known satellites.

== Further exploration ==

== Observation and Exploration ==

[[NASA]] plans to explore Ceres with a probe in 2015. <ref>http://news.bbc.co.uk/2/hi/science/nature/6037844.stm</ref>

 

On September 27, 2007, the [[Dawn mission]] began officially with the launch of Dawn, the first rocket probe to visit the asteroid belt. The Dawn craft carries an ion engine that it will use on the second part of its journey after it makes rendezvous with [[Mars]]. Dawn's two targets are the asteroid [[Vesta]] and the dwarf planet Ceres.<ref name=Dawn>"[http://dawn.jpl.nasa.gov/mission/index.asp Dawn Mission Overview]." [[Jet Propulsion Laboratory|JPL]], [[National Aeronautics and Space Administration|NASA]], March 31, 2008. Accessed June 2, 2008.</ref><ref name=Dawn2>Rayman, Marc D., Fraschetti, Thomas C., Raymond, Carol A., and Russell, Chrisopher T. "[http://dawn.jpl.nasa.gov/mission/Dawn_overview.pdf Dawn: A mission in development for exploration of main belt asteroids Vesta and Ceres]." [[Jet Propulsion Laboratory|JPL]], [[National Aeronautics and Space Administration|NASA]], April 5, 2006. Accessed June 2, 2008.</ref>

== References ==

== References ==

 

* Hamilton, Calvin J. "[http://www.solarviews.com/eng/ceres.htm Dwarf planet Ceres]." ''Views of the Solar System'', 2007. Accessed January 22, 2008.

* Hamilton, Calvin J. "[http://www.solarviews.com/eng/ceres.htm Dwarf planet Ceres]." ''Views of the Solar System'', 2007. Accessed January 22, 2008.

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