Ceres (dwarf planet)

1 Ceres
Ceres as imaged by Dawn, May 2015. Two bright spots dot its surface; the bright crater at right is Hualani, while the bright spot at left is the floor of the crater Oxo
Discovery[1]
Discovered byGiuseppe Piazzi
Discovery date1 January 1801
Designations
1 Ceres
Pronunciation/ˈsɪərz/, SEER-eez
Named after
Cerēs
AdjectivesCererian, -ean (/sɪˈrɪəriən/)
Symbol⚳ (historically astronomical, now mostly astrological)
Orbital characteristics[2]
Epoch 21 January 2022 (JD 2459600.5)
Aphelion2.98 AU (446 million km)
Perihelion2.55 AU (381 million km)
2.77 AU (414 million km)
Eccentricity0.0785
  • 4.60 yr
  • 1680 d
17.9 km/s
291.4°
Inclination
80.3°
7 December 2022
73.6°
SatellitesNone
Proper orbital elements[5]
2.77 AU
0.116
9.65°
78.2 deg / yr
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]
Mean diameter
939.4±0.2 km[6]
2,772,368 km2[a]
Volume434,000,000 km3[7]
Mass
Mean density
2.1616±0.0025 g/cm3[7]
Equatorial surface gravity
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]
Surface temp. min mean max
Kelvin ≈110[14] 235±4[15]
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 inside Neptune's orbit.

Ceres's 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 percent 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, and the brines provide a potential habitat for microbial life.

In January 2014, emissions of water vapour were detected around Ceres, creating a tenuous, transient atmosphere known as an exosphere.[19]

  1. ^ 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.
  2. ^ a b c Cite error: The named reference jpl_sbdb was invoked but never defined (see the help page).
  3. ^ "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.
  4. ^ 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.
  5. ^ "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.
  6. ^ 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.
  7. ^ 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.
  8. ^ 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.
  9. ^ Cite error: The named reference Park2016 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Schorghofer2016 was invoked but never defined (see the help page).
  11. ^ 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.
  12. ^ "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.
  13. ^ Cite error: The named reference Li2006 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Dawn2017 was invoked but never defined (see the help page).
  15. ^ 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.
  16. ^ 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.
  17. ^ King, Bob (5 August 2015). "Let's Get Serious About Ceres". Sky & Telescope. Retrieved 25 July 2022.
  18. ^ Cite error: The named reference AstDys-object was invoked but never defined (see the help page).
  19. ^ "Water Detected on Dwarf Planet Ceres | Science Mission Directorate". science.nasa.gov. Retrieved 20 November 2022.


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