Ceres

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Ceres is seen by the Hubble Space Telescope, Advanced Camera for Surveys (ACS). The contrast has been enhanced to reveal surface details. Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park).

Ceres appears to be a rocky-object and an astronomical object.

Astronomy[edit]

Main source: Astronomy
This image of Ceres was taken by NASA's Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

The image on the right was taken by NASA's Dawn spacecraft on May 5 and 6, 2015, from a distance of 8,400 miles (13,600 kilometers).

Planetary sciences[edit]

Ceres rotates in this sped-up movie comprised of images taken by NASA's Dawn mission during its approach to the dwarf planet. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

The Gamma Ray and Neutron Detector (GRaND) onboard the Dawn spacecraft "is based on similar instruments flown on the Lunar Prospector and Mars Odyssey space missions. It will be used to measure the abundances of the major rock-forming elements (oxygen, magnesium, aluminium, silicon, calcium, titanium, and iron) on Vesta and Ceres, as well as potassium, thorium, uranium, and water (inferred from hydrogen content).[1][2][3][4][5][6]"[7]

"Ceres rotates in this sped-up movie [on the right] comprised of images taken by NASA's Dawn mission during its approach to the dwarf planet. The images were taken on Feb. 19, 2015, from a distance of nearly 29,000 miles (46,000 kilometers). Dawn observed Ceres for a full rotation of the dwarf planet, which lasts about nine hours. The images have a resolution of 2.5 miles (4 kilometers) per pixel."[8]

Theoretical Ceres astronomy[edit]

This is a theoretical cutaway view of asteroid 1 Ceres. Credit: NASA, ESA, and A. Feild (STScI).

Def. "a celestial body that

(a) is in orbit around the Sun,

(b) has sufficient mass for its self-gravity to overcome rigid forces so that it assumes a hydrostatic equilibrium (nearly round) shape,

(c) has not cleared the neighbourhood around its orbit, and

(d) is not a satellite" is called a dwarf planet.[9]

"Ceres ... is the smallest identified dwarf planet in the solar system".[10]

"Observations of 1 Ceres, the largest known asteroid, have revealed that the object may be a "mini planet," and may contain large amounts of pure water ice beneath its surface."[11]

"The observations by NASA's Hubble Space Telescope also show that Ceres shares characteristics of the rocky, terrestrial planets like Earth. Ceres' shape is almost round like Earth's, suggesting that the asteroid may have a "differentiated interior," with a rocky inner core and a thin, dusty outer crust."[11]

"Observations of 1 Ceres, the largest known asteroid, have revealed that the object may be a "mini planet," and may contain large amounts of pure water ice beneath its surface."[12]

"The observations by NASA's Hubble Space Telescope also show that Ceres shares characteristics of the rocky, terrestrial planets like Earth. Ceres' shape is almost round like Earth's, suggesting that the asteroid may have a "differentiated interior," with a rocky inner core and a thin, dusty outer crust."[12]

"Ceres is an embryonic planet. Gravitational perturbations from Jupiter billions of years ago prevented Ceres from accreting more material to become a full-fledged planet."[12]

"Hubble snapped 267 images of Ceres. From those snapshots, the astronomers determined that the asteroid has a nearly round body. The diameter at its equator is wider than at its poles. Computer models show that a nearly round object like Ceres has a differentiated interior, with denser material at the core and lighter minerals near the surface. All terrestrial planets have differentiated interiors. Asteroids much smaller than Ceres have not been found to have such interiors."[12]

"Computer models [such as the image on the right] show that a nearly round object like Ceres has a differentiated interior, with denser material at the core and lighter minerals near the surface. All terrestrial planets have differentiated interiors. Asteroids much smaller than Ceres have not been found to have such interiors."[11]

"The astronomers suspect that water ice may be buried under the asteroid's crust because the density of Ceres is less than that of the Earth's crust, and because the surface bears spectral evidence of water-bearing minerals. They estimate that if Ceres were composed of 25 percent water, it may have more water than all the fresh water on Earth. Ceres' water, unlike Earth's, would be in the form of water ice and located in the mantle, which wraps around the asteroid's solid core."[11]

Planetary astronomy[edit]

The diagram illustrates the orbits of Ceres (blue) and several planets (white/grey). Credit: Orionist.
This shows the relative location of the orbit of Ceres. Credit: WilyD.

"The diagram illustrates the orbits of Ceres (blue) and several planets (white/grey). The segments of orbits below the ecliptic are plotted in darker colours, and the orange plus sign is the Sun's location. The top left diagram is a polar view that shows the location of Ceres in the gap between Mars and Jupiter. The top right is a close-up demonstrating the locations of the perihelia (q) and aphelia (Q) of Ceres and Mars. Interestingly, the perihelia of Ceres (as well as those of several other of the largest MBAs) and Mars are on the opposite sides of the Sun. The bottom diagram is a perspective view showing the inclination of the orbit of Ceres compared to the orbits of Mars and Jupiter."[13]

The animation shows the relative location of the orbit of Ceres.

Visuals[edit]

Ceres is in true color. Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Daniel Macháček.

"This approximately true-color image was taken at 15:27 on May 7, 2015, as Dawn was surveying Ceres in its "Rotation Characterization 3" orbit 13,583 kilometers above the surface. At the terminator, near the top, is Urvara, a large crater with radiating troughs. Closer to the center of the disk is the large Yalode basin, with its flat floor and faint inner ring. Farther down the terminator is the large Mondamin crater. Haulani crater makes a bright splash near the lower right edge of the disk. The cone-shaped Ahuna mons is near center."[14]

Reds[edit]

This image of Ceres taken by Dawn was colorized based on previous images to approximate true color. Credit: Jonathan Chone.

"Over five hours of observations 15 spectra of asteroid [Ceres] with step 2.46 nm in the region 336 - 746 nm were obtained to see whether the spectral characteristics of the Ceres surface changed with the rotation phase. On processing the observational material, it turned out that the spectra of the asteroid are unusually red (i.e., a remarkable rise of relative reflection coefficients with wave length growth occurs)."[15]

Asteroids[edit]

"Ceres ... is ... the only [dwarf planet] in the asteroid belt.[16]"[10]

"Ceres is approximately 580 miles (930 kilometers) across, about the size of Texas. It resides with tens of thousands of other asteroids in the main asteroid belt. Located between Mars and Jupiter, the asteroid belt probably represents primitive pieces of the solar system that never managed to accumulate into a genuine planet. Ceres comprises 25 percent of the asteroid belt's total mass. However, Pluto, our solar system's smallest planet, is 14 times more massive than Ceres."[11]

"The astronomers used Hubble's Advanced Camera for Surveys to study Ceres for nine hours, the time it takes the asteroid to complete a rotation. Hubble snapped 267 images of Ceres. From those snapshots, the astronomers determined that the asteroid has a nearly round body. The diameter at its equator is wider than at its poles."[11]

G asteroids[edit]

"G-type asteroids are a relatively uncommon type of carbonaceous asteroid. The most notable asteroid in this class is 1 Ceres. ... Generally similar to the C-type objects, but containing a strong ultraviolet absorption feature below 0.5 μm."[17]

Asteroid belts[edit]

This is a composite image, to scale, of the asteroids which have been imaged at high resolution. As of 2011 they are, from largest to smallest: 4 Vesta, 21 Lutetia, 253 Mathilde, 243 Ida and its moon Dactyl, 433 Eros, 951 Gaspra, 2867 Šteins, 25143 Itokawa. Credit: NASA/JPL-Caltech/JAXA/ESA.
The asteroid belt is shown in (white) and the Trojan asteroids (green). Credit: .

Def. a "region of the orbital plane of the solar system located between the orbits of Mars and Jupiter which is occupied by numerous minor planets and the dwarf planet Ceres"[18] is called an asteroid belt.

"The MB group is the most numerous group of MCs. ... 50 % of the MB Mars-crossers [MCs] become ECs within 59.9 Myr and [this] contribution ... dominates the production of ECs"[19]. MB denotes the main belt of asteroids.[19]

"The interplanetary medium includes interplanetary dust, cosmic rays and hot plasma from the solar wind. The temperature of the interplanetary medium varies. For dust particles within the asteroid belt, typical temperatures range from 200 K (−73 °C) at 2.2 AU down to 165 K (−108 °C) at 3.2 AU[20] The density of the interplanetary medium is very low, about 5 particles per cubic centimeter in the vicinity of the Earth; it decreases with increasing distance from the sun, in inverse proportion to the square of the distance. It is variable, and may be affected by magnetic fields and events such as coronal mass ejections. It may rise to as high as 100 particles/cm³."[21]

"The hydromagnetic approach led to the discovery of two important observational regularities in the solar system: (1) the band structure [such as in the rings of Saturn and in the asteroid belt], and (2) the cosmogonic shadow effect (the two-thirds fall down effect)."[22]

"The majority of known asteroids orbit within the asteroid belt between the orbits of Mars and Jupiter ... This belt is now estimated to contain between 1.1 and 1.9 million asteroids larger than 1 km in diameter,[23] and millions of smaller ones.[24]"[25]

Craters[edit]

The 6-mile-wide (10-kilometer-wide) crater named Oxo is the second-brightest feature on Ceres. Credit: NASA / JPL-Caltech / UCLA / Max Planck Institute for Solar System Studies / German Aerospace Center / IDA / Planetary Science Institute.
A variety of craters and other geological features can be found on dwarf planet Ceres. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
This image taken by NASA's Dawn spacecraft, shows Occator crater on Ceres, home to a collection of intriguing bright spots. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA's Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI.

"The 6-mile-wide (10-kilometer-wide) crater named Oxo Crater is the second-brightest feature on Ceres. Only Occator's central area is brighter. Oxo lies near the 0 degree meridian that defines the edge of many Ceres maps, making this small feature easy to overlook. NASA Dawn spacecraft took this image in its low-altitude mapping orbit, at a distance of 240 miles (385 kilometers) from the surface of Ceres."[26]

"Oxo is also unique because of the relatively large "slump" in its crater rim, where a mass of material has dropped below the surface. Dawn science team members are also examining the signatures of minerals on the crater floor, which appear different than elsewhere on Ceres."[26]

"The image has been rotated so that north on Ceres is up."[26]

"A variety of craters [Urvara and Yalode on the right] and other geological features can be found on dwarf planet Ceres. NASA's Dawn spacecraft took this image of Ceres from an altitude of 2,700 miles (4,400 kilometers). The image, with a resolution of 1,400 feet (410 meters) per pixel, was taken on June 5, 2015."[27]

"The bright spots [on the left in Occator crater] are much brighter than the rest of Ceres' surface, and tend to appear overexposed in most images. This view is a composite of two images of Occator: one using a short exposure that captures the detail in the bright spots, and one where the background surface is captured at normal exposure."[28]

"The images were obtained by Dawn during the mission's High Altitude Mapping Orbit (HAMO) phase, from which the spacecraft imaged the surface at a resolution of about 450 feet (140 meters) per pixel."[28]

"The view [second down on the left] was produced by combining the highest resolution images of Occator obtained in February 2016 (at image scales of 35 meters, or 115 feet, per pixel) with color images obtained in September 2015 (at image scales of 135 meters, or about 440 feet, per pixel). The three images used to produce the color were taken using spectral filters centered at 438, 550 and 965 nanometers (the latter being slightly beyond the range of human vision, in the near-infrared)."[29]

"The crater measures 57 miles (92 kilometers) across and 2.5 miles (4 kilometers) deep. Dawn's close-up view reveals a dome in a smooth-walled pit in the bright center of the crater. Numerous linear features and fractures crisscross the top and flanks of this dome."[29]

Volcanoes[edit]

Main source: Volcanoes
These color topographic views show variations in surface height around Ahuna Mons, a mysterious mountain on Ceres. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

The "views [such as the one on the right] were made using images taken by NASA's Dawn spacecraft during its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometers) from the surface. The resolution of the component images is about 120 feet (35 meters) per pixel."[30]

"Elevations span a range of about 5.5 miles (9 kilometers) from the lowest places in the region to the highest terrains. Blue represents the lowest elevation, and brown is the highest. The streaks running down the side of the mountain, which appear white in the grayscale view, are especially bright parts of the surface (the brightness does not relate to elevation). The elevations are from a shape model generated using images taken at varying sun and viewing angles during Dawn's lower-resolution, high-altitude mapping orbit (HAMO) phase."[30]

Recent history[edit]

Main sources: History/Recent and Recent history

The recent history period dates from around 1,000 b2k to present.

“When Ceres has an opposition near the perihelion, it can reach a visual magnitude of +6.7.[31] This is generally regarded as too dim to be seen with the naked eye, but under exceptional viewing conditions a very sharp-sighted person may be able to see this dwarf planet.”[10]

"Besides being the largest asteroid, Ceres also was the first asteroid to be discovered. Sicilian astronomer Father Giuseppe Piazzi spotted the object in 1801. Piazzi was looking for suspected planets in a large gap between the orbits of Mars and Jupiter. As more such objects were found in the same region, they became known as "asteroids" or "minor planets.""[11]

Hypotheses[edit]

Main source: Hypotheses
  1. Ceres is another cratered surface, rocky object.

See also[edit]

References[edit]

  1. "Science Payload". Retrieved 2010-03-21. 
  2. "GRaND science instrument moves closer to launch from Cape". Retrieved 2010-03-21. 
  3. Kevin Righter, Michael J. Drake (1997). "A magma ocean on Vesta: Core formation and petrogenesis of eucrites and diogenites". Meteoritics & Planetary Science 32 (6): 929–944. doi:10.1111/j.1945-5100.1997.tb01582.x. 
  4. Michael J. Drake (2001). "The eucrite/Vesta story". Meteoritics & Planetary Science 36 (4): 501–13. doi:10.1111/j.1945-5100.2001.tb01892.x. 
  5. Thomas H. Prettyman (2004). "Mapping the elemental composition of Ceres and Vesta: Dawn[quotation mark]s gamma ray and neutron detector". Proceedings of SPIE. 5660. pp. 107. doi:10.1117/12.578551. 
  6. . doi:10.1109/TNS.2003.815156. 
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  15. L. F. Golubeva and D. I. Shestopalov (1995). "Spectrometry of Minor Planets. The Possible Reason for Changes in Reflection Spectrum of 1 Ceres". Solar System Research 29 (1): 32-40. http://www.researchgate.net/publication/237006685_Spectrometry_of_minor_planets._The_possible_reason_for_changes_in_reflection_spectrum_of_1_Ceres/file/3deec51b96d02d83d6.pdf. Retrieved 2013-07-28. 
  16. "NASA – Dawn at a Glance". NASA. Archived from the original on 2011-10-05. Retrieved 14 August 2011. 
  17. Lua error in Module:Citation/CS1 at line 3505: bad argument #1 to 'pairs' (table expected, got nil).
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  19. 19.0 19.1 Patrick Michel, Fabbio Migliorini, Alessandro Morbidelli, Vincenzo Zappalà (June 2000). "The Population of Mars-Crossers: Classification and Dynamical Evolution". Icarus 145 (2): 332-47. doi:10.1006/icar.2000.6358. http://www.obs-nice.fr/morby/papers/6358a.pdf. Retrieved 2011-10-06. 
  20. Low, F. J.; et al. (1984). "Infrared cirrus – New components of the extended infrared emission". Astrophysical Journal, Part 2 – Letters to the Editor 278: L19–L22. doi:10.1086/184213. http://adsabs.harvard.edu//abs/1984ApJ...278L..19L. 
  21. Lua error in Module:Citation/CS1 at line 3505: bad argument #1 to 'pairs' (table expected, got nil).
  22. Hannes Alfvén (October 1981). "The Voyager 1/Saturn Encounter and the Cosmogonic Shadow Effect". Astrophysics and Space Science 79 (2): 491-505. doi:10.1007/BF00649444. http://adsabs.harvard.edu/abs/1981Ap&SS..79..491A. Retrieved 2013-12-19. 
  23. Edward Tedesco, Leo Metcalfe (April 4, 2002). "New study reveals twice as many asteroids as previously believed". European Space Agency. Retrieved 2008-02-21. 
  24. World Book at NASA
  25. Lua error in Module:Citation/CS1 at line 3505: bad argument #1 to 'pairs' (table expected, got nil).
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  31. Menzel, Donald H.; and Pasachoff, Jay M. (1983). A Field Guide to the Stars and Planets (2nd ed.). Boston, MA: Houghton Mifflin. p. 391. ISBN 978-0-395-34835-2. 

External links[edit]

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