Ceres (dwarf planet)
_(cropped).jpg)
A view of Ceres in natural color, pictured by the Dawn spacecraft in May 2015.
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| Discovery | |||||||||
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| Discovered by | Giuseppe Piazzi | ||||||||
| Discovery date | 1 January 1801 | ||||||||
| Designations | |||||||||
| MPC designation | 1 Ceres | ||||||||
| Pronunciation | /ˈsɪəriːz/ | ||||||||
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Named after
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Cerēs | ||||||||
| A899 OF; 1943 XB | |||||||||
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Dwarf planet Asteroid belt |
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| Adjectives | Cererian /sᵻˈrɪəriən/, rarely Cererean /sɛrᵻˈriːən/ |
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| Orbital characteristics | |||||||||
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Epoch 2014-Dec-09 (JD 2,457,000.5) |
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| Aphelion |
2.9773 AU (445,410,000 km) |
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| Perihelion |
2.5577 AU (382,620,000 km) |
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2.7675 AU (414,010,000 km) |
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| Eccentricity | 0.075823 | ||||||||
| 4.60 yr 1,681.63 d |
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| 466.6 d 1.278 yr |
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Average orbital speed
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17.905 km/s | ||||||||
| 95.9891° | |||||||||
| Inclination |
10.593° to ecliptic 9.20° to invariable plane |
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| 80.3293° | |||||||||
| 72.5220° | |||||||||
| Satellites | None | ||||||||
| Proper orbital elements | |||||||||
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Proper semi-major axis
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2.7670962 AU | ||||||||
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Proper eccentricity
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0.1161977 | ||||||||
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Proper inclination
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9.6474122° | ||||||||
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Proper mean motion
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78.193318 deg / yr | ||||||||
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Proper orbital period
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4.60397 yr (1681.601 d) |
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Precession of perihelion
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54.070272 arcsec / yr | ||||||||
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Precession of the ascending node
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−59.170034 arcsec / yr | ||||||||
| Physical characteristics | |||||||||
| Dimensions | (965.2 × 961.2 × 891.2) ± 2.0 km |
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Mean radius
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473 km | ||||||||
| 2,770,000 km2 | |||||||||
| Volume | 421,000,000 km3 | ||||||||
| Mass |
(9.393±0.005)×1020 kg 0.0128 Moons |
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Mean density
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2.161±0.009 g/cm3 | ||||||||
| 0.28 m/s2 0.029 g |
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| 0.37 (estimate) | |||||||||
| 0.51 km/s | |||||||||
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Sidereal rotation period
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0.3781 d 9.074170±0.000002 h |
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Equatorial rotation velocity
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92.61 m/s | ||||||||
| 4° | |||||||||
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North pole right ascension
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294.18° | ||||||||
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North pole declination
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66.764° | ||||||||
| Albedo | 0.090±0.0033 (V-band geometric) | ||||||||
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Spectral type
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C | ||||||||
| 6.64 to 9.34 | |||||||||
| 3.36±0.02 | |||||||||
| 0.854″ to 0.339″ | |||||||||
(9.393±0.005)×1020 kg
Ceres (/ˈsɪəriːz/;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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Wikipedia