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Ceres (dwarf planet)

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Ceres Ceres symbol.svg
Discovery and designation
Discovered byGiuseppe Piazzi
Discovery timeJanuary 1, 1801
Name1 Ceres
Other namesA899 OF; 1943 XB
Groupdwarf planet
main belt
Reference date November 26, 2005
(JD 2453700.5)[1]
Longest distance from the Sun447,838,164 km
2.987 AU
Shortest distance from the Sun381,419,582 km
2.544 AU
Longest distance from the center of its orbital path
("semi-major axis")
414,703,838 km
2.765 956 424 AU[2]
How egg-shaped its orbit is
How long it takes to complete an orbit1679.819 days
4.599 years
Average speed17.882 km/s
Mean anomaly108.509°
Angle above the reference plane
Longitude of where it comes up through the reference plane80.40696°[2]
Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
Size and Other Qualities
Average distance from its center to its surface473 km[3]
Flatness at the poles0.067 ± 0.005
Mass9.46 ± 0.04×1020 kg[4][5]
Average density2.08 g/cm3[6]
Gravity at its surface0.27 m/s²
0.028 g
Slowest speed able to escape into space
("escape velocity")
0.51 km/s
How long it takes to turn around one time
(in relation to the stars)
0.3781 d
9.074 h[7]
How much light it reflects0.113 (geometric)[8]
Surface temp. Min. Avg. Max.
Kelvin ~167 K[11] 239 K[11]
Light-band group
("spectral type")
Seeming brightness
("apparent magnitude")
6.7 to 9.32
True brightness
("absolute magnitude")
Seeming size
("angular diameter")
0.84"[10] to 0.33"

Ceres, also known as 1 Ceres, is the smallest dwarf planet in the Solar System and the only one in the main asteroid belt.

It was discovered on 1 January 1801, by Giuseppe Piazzi,[12] and is named after the Roman goddess Ceres, as the goddess of growing plants, the harvest, and of motherly love. After about 200 years from its discovery, the International Astronomical Union decided to upgrade Ceres from an asteroid (or minor planet) to dwarf planetary status in 2006.

With a diameter of about 950 km, Ceres is by far the largest and most massive object in the asteroid belt, and has about a third of the belt's total mass. It was once thought to be smaller than Vesta, which is brighter. The asteroid is spherical, unlike the irregular shapes of smaller bodies with lower gravity. At its brightest it is still too dim to be seen with the naked eye.[13]

On September 27, 2007, NASA launched the Dawn space probe to explore Ceres and Vesta. In 2015, Dawn became the first spacecraft to visit a dwarf planet, arriving at Ceres a few months before NASA's New Horizons spacecraft visited Pluto, another dwarf planet.

Ceres has an unusual crater, Occator which contains bright salts.


Close up image of bright salts, imaged by the Dawn spacecraft, in the crater Occator on Ceres.

Related pages


  1. Ted Bowell, Bruce v (January 2, 2003). "Asteroid Observing Services". Lowell Observatory. Retrieved 2007-01-17. 
  2. 2.0 2.1 2.2 2.3 2.4 Yeomans, Donald K. (July 5, 2007). "1 Ceres". JPL Small-Body Database Browser.;orb=1. Retrieved 2007-07-05. —The listed values were rounded at the magnitude of uncertainty (1-sigma).
  3. "05. Dawn Explores Ceres Results from the Survey Orbit.pptx". 
  4. Pitjeva, E.V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research 39 (3): 176. doi:10.1007/s11208-005-0033-2 . 
  5. D. T. Britt | display-authors = etal Asteroid density, porosity, and structure, pp. 488 in Asteroids III, University of Arizona Press (2002).
  6. Thomas, P.C.Expression error: Unrecognized word "etal". (2005). "Differentiation of the asteroid Ceres as revealed by its shape". Nature 437: 224-226. doi:10.1038/nature03938 . 
  7. Harris, A.W. (2006). "Asteroid Lightcurve Derived Data. EAR-A-5-DDR-DERIVED-LIGHTCURVE-V8.0.". In Warner, B.D. and Pravec, P.. NASA Planetary Data System. Retrieved 2007-03-15. 
  8. 8.0 8.1 Tedesco, E.F. (2004). "IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0.". Noah, P.V.; Noah, M.; Price, S.D.. Planetary Data System. Retrieved 2007-03-15. 
  9. Neese, C. (ed.) (2005). "Asteroid Taxonomy.EAR-A-5-DDR-TAXONOMY-V5.0.". NASA Planetary Data System. Retrieved 2007-03-15. 
  10. Ceres Angular Size @ Feb 2009 Opposition: 974km dia / (1.58319AU * 149 597 870km) * 206265 = 0.84"
  11. 11.0 11.1 Saint-Pé, O.; Combes, N. and Rigaut F. (1993). "Ceres surface properties by high-resolution imaging from Earth". Icarus 105: 271-281. doi:10.1006/icar.1993.1125 . 
  12. Piazzi, Giuseppe (1801) (in Italian). Risultati delle osservazioni della nuova Stella scoperta il dì 1 gennajo all'Osservatorio Reale di Palermo. Palermo. 
  13. Ceres at