Geology of Ceres

Dawn spacecraft view of Occator Crater on Ceres in approximate true color, this image was taken on May 4, 2015.[1]

The geology of Ceres consists of the characteristics of the surface, crust, and interior of dwarf planet Ceres. Surface of Ceres is similar with C-type asteroids,[2] but spectral features of carbonates and clay minerals are usually absent in the spectra of other C-type asteroids. Sometimes Ceres is classified as a G-type asteroid.

Internal structure

Diagram showing a possible internal structure of Ceres

Ceres's oblateness is consistent with a differentiated body, a rocky core overlain with an icy mantle.[3] This 100-kilometer-thick mantle (23%–28% of Ceres by mass; 50% by volume)[4] contains up to 200 million cubic kilometers of water, which would be more than the amount of fresh water on Earth.[5] This result is supported by the observations made by the Keck telescope in 2002 and by evolutionary modeling.[6][7] Also, some characteristics of its surface and history (such as its distance from the Sun, which weakened solar radiation enough to allow some fairly low-freezing-point components to be incorporated during its formation), point to the presence of volatile materials in the interior of Ceres.[7] It has been suggested that a remnant layer of liquid water may have survived to the present under a layer of ice.[6][8] Measurements taken by Dawn confirm that Ceres is both differentiated and has a shape consistent with hydrostatic equilibrium,[9] which makes Ceres the smallest object confirmed to be in hydrostatic equilibrium, being 600 km smaller and less than half the mass of Saturn's moon Rhea, the next smallest such object.[10]

Internal structure of Ceres.

Orientation

Ceres has an axial tilt of about 4°,[11] a small part of its pole is currently not observable to Dawn.

Craters

Large number of Cererian craters have central pits, and many have central peaks.

Surface of Ceres has a large number of craters with low relief, indicating that they lie over a relatively soft surface, probably of water ice. A crater is extremely low relief, with a diameter of 283.88 kilometers, reminiscent of large, flat craters on Tethys and Iapetus.

Faculae

Several bright surface features were discovered on the dwarf planet Ceres by the Dawn spacecraft in 2015.[12]

The brightest spot is located in the middle of Occator crater, and is called as "bright spot 5".

Maps

References

  1. ↑ "Dawn data from Ceres publicly released: Finally, color global portraits!". www.planetary.org. Retrieved 2016-02-04.
  2. ↑ http://irtfweb.ifa.hawaii.edu/~elv/icarus185.563.pdf
  3. ↑ Thomas, P. C.; Parker, J. Wm.; McFadden, L. A.; et al. (2005). "Differentiation of the asteroid Ceres as revealed by its shape". Nature 437 (7056): 224–226. Bibcode:2005Natur.437..224T. doi:10.1038/nature03938. PMID 16148926.
  4. ↑ 0.72–0.77 anhydrous rock by mass, per William B. McKinnon (2008) "On The Possibility Of Large KBOs Being Injected Into The Outer Asteroid Belt". American Astronomical Society, DPS meeting No. 40, #38.03 Archived 5 October 2011 at WebCite
  5. ↑ Carey, Bjorn (7 September 2005). "Largest Asteroid Might Contain More Fresh Water than Earth". SPACE.com. Archived from the original on 5 October 2011. Retrieved 16 August 2006.
  6. 1 2 McCord, T. B.; Sotin, C. (21 May 2005). "Ceres: Evolution and current state". Journal of Geophysical Research: Planets 110 (E5): E05009. Bibcode:2005JGRE..110.5009M. doi:10.1029/2004JE002244. Retrieved 7 March 2015.
  7. 1 2 Carry, Benoit; et al. (2007). "Near-Infrared Mapping and Physical Properties of the Dwarf-Planet Ceres" (PDF). Astronomy & Astrophysics 478 (1): 235–244. arXiv:0711.1152. Bibcode:2008A&A...478..235C. doi:10.1051/0004-6361:20078166. Archived from the original (PDF) on 30 May 2008.
  8. ↑ O'Brien, D. P.; Travis, B. J.; Feldman, W. C.; Sykes, M. V.; Schenk, P. M.; Marchi, S.; Russell, C. T.; Raymond, C. A. (March 2015). "The Potential for Volcanism on Ceres due to Crustal Thickening and Pressurization of a Subsurface Ocean" (PDF). 46th Lunar and Planetary Science Conference. p. 2831. Retrieved 1 March 2015.
  9. ↑ "DPS 2015: First reconnaissance of Ceres by Dawn".
  10. ↑
  11. ↑ http://naif.jpl.nasa.gov/pub/naif/DAWN/kernels/pck/dawn_ceres_v05.tpc
  12. ↑ "Mysterious Bright Spots Shine on Dwarf Planet Ceres (Photos)". Space.com. Retrieved 2016-02-05.
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