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Ceres (dwarf planet)

Ceres ⚳
Ceres - RC3 - Haulani Crater (22381131691) (cropped).jpg
A view of Ceres in natural color, pictured by the Dawn spacecraft in May 2015.
Discovery
Discovered by Giuseppe Piazzi
Discovery date 1 January 1801
Designations
MPC designation 1 Ceres
Pronunciation /ˈsɪərz/
Named after
Cerēs
A899 OF; 1943 XB
Dwarf planet
Asteroid belt
Adjectives Cererian /sˈrɪəriən/,
rarely Cererean /sɛrˈrən/
Orbital characteristics
Epoch 2014-Dec-09
(JD 2,457,000.5)
Aphelion 2.9773 AU
(445,410,000 km)
Perihelion 2.5577 AU
(382,620,000 km)
2.7675 AU
(414,010,000 km)
Eccentricity 0.075823
4.60 yr
1,681.63 d
466.6 d
1.278 yr
Average orbital speed
17.905 km/s
95.9891°
Inclination 10.593° to ecliptic
9.20° to invariable plane
80.3293°
72.5220°
Satellites None
Proper orbital elements
2.7670962 AU
Proper eccentricity
0.1161977
Proper inclination
9.6474122°
Proper mean motion
78.193318 deg / yr
4.60397 yr
(1681.601 d)
Precession of perihelion
54.070272 arcsec / yr
Precession of the ascending node
−59.170034 arcsec / yr
Physical characteristics
Dimensions (965.2 × 961.2
× 891.2) ± 2.0 km
Mean radius
473 km
2,770,000 km2
Volume 421,000,000 km3
Mass

(9.393±0.005)×1020 kg

0.00015 Earths
0.0128 Moons
Mean density
2.161±0.009 g/cm3
0.28 m/s2
0.029 g
0.37 (estimate)
0.51 km/s
Sidereal rotation period
0.3781 d
9.074170±0.000002 h
Equatorial rotation velocity
92.61 m/s
North pole right ascension
294.18°
North pole declination
66.764°
Albedo 0.090±0.0033 (V-band geometric)
Surface temp. min mean max
Kelvin ? ≈ 168 K 235 K
Spectral type
C
6.64 to 9.34
3.36±0.02
0.854″ to 0.339″

(9.393±0.005)×1020 kg

Ceres (/ˈsɪərz/;minor-planet designation: 1 Ceres) is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. The 33rd-largest known body in the Solar System, it is the only dwarf planet within the orbit of Neptune. Composed of rock and ice, Ceres is estimated to compose approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest, it is too dim to be seen with the naked eye, except under extremely dark skies.

Ceres was the first asteroid discovered, by Giuseppe Piazzi at Palermo on 1 January 1801. It was originally considered a planet, but was reclassified as an asteroid in the 1850s when many other objects in similar orbits were discovered.

Ceres appears to be differentiated into a rocky core and icy mantle, and may have a remnant internal ocean of liquid water under the layer of ice. The surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected, because large bodies in the asteroid belt typically do not emit vapor, a hallmark of comets.


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