&sq=&lang=&file=File:Ceres_-_RC3_-_Haulani_Crater_(22381131691)_(cropped).jpg) | |||||||||
| Discovery[1] | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Discovered by | Giuseppe Piazzi | ||||||||
| Discovery date | 1 January 1801 | ||||||||
| Designations | |||||||||
| 1 Ceres | |||||||||
| Pronunciation | /ˈsɪəriːz/, SEER-eez | ||||||||
Named after | Cerēs | ||||||||
| Adjectives | Cererian, -ean (/sɪˈrɪəriən/) | ||||||||
| Symbol | &sq=&lang=&file=File:Ceres_symbol_(bold).svg){kind=small} | ||||||||
| Orbital characteristics[2] | |||||||||
| Epoch 21 January 2022 (JD 2459600.5) | |||||||||
| Aphelion | 2.98 AU (446 million km) | ||||||||
| Perihelion | 2.55 AU (381 million km) | ||||||||
| 2.77 AU (414 million km) | |||||||||
| Eccentricity | 0.0785 | ||||||||
| |||||||||
Average orbital speed | 17.9 km/s | ||||||||
| 291.4° | |||||||||
| Inclination |
| ||||||||
| 80.3° | |||||||||
| 7 December 2022 | |||||||||
| 73.6° | |||||||||
| Satellites | None | ||||||||
| Proper orbital elements[5] | |||||||||
Proper semi-major axis | 2.77 AU | ||||||||
Proper eccentricity | 0.116 | ||||||||
Proper inclination | 9.65° | ||||||||
Proper mean motion | 78.2 deg / yr | ||||||||
Proper orbital period | 4.60358 yr (1681.458 d) | ||||||||
Precession of perihelion | 54.1 arcsec / yr | ||||||||
Precession of the ascending node | −59.2 arcsec / yr | ||||||||
| Physical characteristics | |||||||||
| Dimensions | (966.2 × 962.0 × 891.8) ± 0.2 km[6] | ||||||||
| 939.4±0.2 km[6] | |||||||||
| 2,772,368 km2[a] | |||||||||
| Volume | 434,000,000 km3[7] | ||||||||
| Mass | |||||||||
Mean density | 2.1616±0.0025 g/cm3[7] | ||||||||
Equatorial surface gravity | 0.284 m/s2 (0.0290 g0)[a] | ||||||||
| 0.36±0.15[8][b] (estimate) | |||||||||
Equatorial escape velocity | 0.516 km/s[a] 1141 mph | ||||||||
| 9.074170±0.000001 h[2] | |||||||||
Equatorial rotation velocity | 92.61 m/s[a] | ||||||||
| ≈4°[10] | |||||||||
North pole right ascension | 291.42744°[11] | ||||||||
North pole declination | 66.76033°[12] | ||||||||
| 0.090±0.0033 (V-band)[13] | |||||||||
| |||||||||
| C[16] | |||||||||
| 3.34[2] | |||||||||
| 0.854″ to 0.339″ | |||||||||
Ceres (minor-planet designation: 1 Ceres) is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, 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 a dwarf planet, the only one not beyond Neptune's orbit.
Ceres' diameter is about one-fourth that of the Moon. Its small size means that even at its brightest it is too dim to be seen by the naked eye, except under extremely dark skies. Its apparent magnitude ranges from 6.7 to 9.3, peaking at opposition (when it is closest to Earth) once every 15- to 16-month synodic period. As a result, its surface features are barely visible even with the most powerful telescopes, and little was known about it until the robotic NASA spacecraft Dawn approached Ceres for its orbital mission in 2015.
Dawn found Ceres's surface to be a mixture of water ice and hydrated minerals such as carbonates and clay. Gravity data suggest Ceres to be partially differentiated into a muddy (ice-rock) mantle/core and a less dense but stronger crust that is at most thirty per cent ice by volume. Although Ceres likely lacks an internal ocean of liquid water, brines still flow through the outer mantle and reach the surface, allowing cryovolcanoes such as Ahuna Mons to form roughly every fifty million years. This makes Ceres the closest known cryovolcanically active body to the Sun. Additionally, Ceres hosts an extremely tenuous and transient atmosphere of water vapour, vented from localised sources on its surface.
- ^ Schmadel, Lutz (2003). Dictionary of minor planet names (5th ed.). Germany: Springer. p. 15. ISBN 978-3-540-00238-3. Archived from the original on 16 February 2021. Retrieved 21 January 2021.
- ^ a b c Cite error: The named reference
jpl_sbdbwas invoked but never defined (see the help page). - ^ "On The New Planet Ceres". A Journal of Natural Philosophy, Chemistry, and the Arts. 1802. Archived from the original on 29 May 2022. Retrieved 29 May 2022.
- ^ Souami, D.; Souchay, J. (July 2012). "The solar system's invariable plane". Astronomy & Astrophysics. 543: 11. Bibcode:2012A&A...543A.133S. doi:10.1051/0004-6361/201219011. A133.
- ^ "AstDyS-2 Ceres Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. Archived from the original on 21 November 2011. Retrieved 1 October 2011.
- ^ a b Ermakov, A. I.; Fu, R. R.; Castillo-Rogez, J. C.; Raymond, C. A.; Park, R. S.; Preusker, F.; Russell, C. T.; Smith, D. E.; Zuber, M. T. (November 2017). "Constraints on Ceres' Internal Structure and Evolution From Its Shape and Gravity Measured by the Dawn Spacecraft". Journal of Geophysical Research: Planets. 122 (11): 2267–2293. Bibcode:2017JGRE..122.2267E. doi:10.1002/2017JE005302. S2CID 133739176.
- ^ a b c Park, R.S.; Vaughan, A.T.; Konopliv, A.S.; Ermakov, A.I.; Mastrodemos, N.; Castillo-Rogez, J.C.; Joy, S.P.; Nathues, A.; Polanskey, C.A.; Rayman, M.D.; Riedel, J.E.; Raymond, C.A.; Russell, C.T.; Zuber, M.T. (February 2019). "High-resolution shape model of Ceres from stereophotoclinometry using Dawn Imaging Data". Icarus. 319: 812–827. Bibcode:2019Icar..319..812P. doi:10.1016/j.icarus.2018.10.024. S2CID 126268402.
- ^ Mao, X.; McKinnon, W. B. (2018). "Faster paleospin and deep-seated uncompensated mass as possible explanations for Ceres' present-day shape and gravity". Icarus. 299: 430–442. Bibcode:2018Icar..299..430M. doi:10.1016/j.icarus.2017.08.033.
- ^ Cite error: The named reference
Park2016was invoked but never defined (see the help page). - ^ Cite error: The named reference
Schorghofer2016was invoked but never defined (see the help page). - ^ Konopliv, A.S.; Park, R.S.; Vaughan, A.T.; Bills, B.G.; Asmar, S.W.; Ermakov, A.I.; Rambaux, N.; Raymond, C.A.; Castillo-Rogez, J.C.; Russell, C.T.; Smith, D.E.; Zuber, M.T. (2018). "The Ceres gravity field, spin pole, rotation period and orbit from the Dawn radiometric tracking and optical data". Icarus. 299: 411–429. Bibcode:2018Icar..299..411K. doi:10.1016/j.icarus.2017.08.005.
- ^ "Asteroid Ceres P_constants (PcK) SPICE kernel file". NASA Navigation and Ancillary Information Facility. Archived from the original on 28 July 2020. Retrieved 8 September 2019.
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Dawn2017was invoked but never defined (see the help page). - ^ Tosi, F.; Capria, M. T.; et al. (2015). "Surface temperature of dwarf planet Ceres: Preliminary results from Dawn". 46th Lunar and Planetary Science Conference: 11960. Bibcode:2015EGUGA..1711960T. Retrieved 25 May 2021.
- ^ Rivkin, A. S.; Volquardsen, E. L.; Clark, B. E. (2006). "The surface composition of Ceres: Discovery of carbonates and iron-rich clays" (PDF). Icarus. 185 (2): 563–567. Bibcode:2006Icar..185..563R. doi:10.1016/j.icarus.2006.08.022. Archived (PDF) from the original on 28 November 2007. Retrieved 8 December 2007.
- ^ King, Bob (5 August 2015). "Let's Get Serious About Ceres". Sky & Telescope. Retrieved 25 July 2022.
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