Ceres (dwarf planet)

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Ceres (dwarf planet)

From Wikipedia, the free encyclopedia

Ceres as seen by Hubble Space Telescope(ACS).^[1] The contrast has been enhanced to reveal surface details.

Discovery^[2]

Discovered by

Giuseppe Piazzi

Discovery date

1 January 1801

Designations

MPC designation

1 Ceres

Pronunciation

/ˈsɪəriːz/ seer-eez

Named after

Cerēs

Alternative names

A899 OF; 1943 XB

Minor planet category

dwarf planet
main belt

Adjectives

Cererian /sɨˈrɪəri.ən/
or Cererean /sɛrɨˈriːən/^[3]

Orbital characteristics^[5]

Epoch 2014-Dec-09
(JD 2457000.5)

Aphelion

2.9773 AU
(445410000 km)

Perihelion

2.5577 AU
(382620000 km)

Semi-major axis

2.7675 AU
(414010000 km)

Eccentricity

0.075823

Orbital period

4.60 yr
1681.63 d

Synodic period

466.6 d
1.278 yr

Average orbital speed

17.905 km/s

Mean anomaly

95.9891°

Inclination

10.593° to Ecliptic
9.20° to Invariable plane^[4]

Longitude of ascending node

80.3293°

Argument of perihelion

72.5220°

Satellites

None

Proper orbital elements^[6]

Proper semi-major axis

2.7670962 AU

Propereccentricity

0.1161977

Properinclination

9.6474122°

Proper mean motion

78.193318 deg / yr

Proper orbital period

4.60397 yr
(1681.601 d)

Precession ofperihelion

54.070272 arcsec / yr

Precession of theascending node

−59.170034 arcsec / yr

Physical characteristics

Mean radius

476.2±1.7 km

Equatorial radius

487.3±1.8 km^[7]

Polar radius

454.7±1.6 km^[7]

Surface area

2850000 km²

Mass

(9.43±0.07)×10²⁰ kg,^[8]9.47±??^[9]

0.00015 Earths
0.0128 Moons

Mean density

2.077±0.036 g/cm³,^[7]2.09±??^[9]

Surface gravity

0.28 m/s^2[9]
0.029 g

Escape velocity

0.51 km/s^[10]

Sidereal rotation period

0.3781 d
9.074170±0.000002 h^[11]

Axial tilt

≈ 3°^[7]

North poleright ascension

19^h 24^m
291°^[7]

North poledeclination

59°^[7]

Albedo

0.090±0.0033 (V-band geometric)^[12]

Surface temp.	min	mean	max
Kelvin	?	≈ 168 K[16]	235 K[17]

Spectral type

C^[13]

Apparent magnitude

6.64^[14] to 9.34^[15]

Absolute magnitude (H)

3.36±0.02^[12]

Angular diameter

0.854″ to 0.339″

Ceres (minor-planet designation 1 Ceres) /ˈsɪəriːz/ (seer-eez)^[18] is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. It is composed of rock and ice, is 950 km (590 mi) in diameter, and contains a third of the mass of the asteroid belt. It is the largest asteroid, and the only dwarf planet in the inner Solar System. It was the first asteroid to be discovered, on 1 January 1801 by Giuseppe Piazzi in Palermo, though at first it was considered to be a planet. The unmanned Dawn spacecraft is scheduled to arrive at Ceres in early 2015.

Ceres appears to be differentiated into a rocky core and icy mantle, and may harbor an internal ocean of liquid water under its surface. The surface is probably a mixture of water ice and varioushydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was somewhat unexpected, as large bodies in the asteroid belt do not typically emit vapor, a hallmark of comets.

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.

Contents

  [hide] 

• 1 Discovery
• 2 Names
• 3 Classification
• 4 Physical characteristics
  • 4.1 Internal structure
  • 4.2 Surface
  • 4.3 Atmosphere
• 5 Potential for extraterrestrial life
• 6 Orbit
  • 6.1 Transits of planets from Ceres
• 7 Origin and evolution
  • 7.1 Occultations
• 8 Exploration
• 9 See also
• 10 Notes
• 11 References
• 12 External links

Discovery[edit]

Johann Elert Bode, in 1772, first suggested that an undiscovered planet could exist between the orbits of Mars and Jupiter.^[19] Kepler had already noticed the gap between Mars and Jupiter in 1596.^[19] Bode based his idea on the Titius–Bode law—a now-discredited hypothesis Johann Daniel Titius first proposed in 1766—observing that there was a regular pattern in the semi-major axes of the orbits of known planets, marred only by the large gap between Mars and Jupiter.^[19][20] The pattern predicted that the missing planet ought to have an orbit with a semi-major axis near 2.8AU.^[20] William Herschel's discovery of Uranus in 1781^[19] near the predicted distance for the next body beyond Saturn increased faith in the law of Titius and Bode, and in 1800, a group headed byFranz Xaver von Zach, editor of the Monatliche Correspondenz, sent requests to twenty-four experienced astronomers, asking that they combine their efforts and begin a methodical search for the expected planet.^[19][20] Although they did not discover Ceres, they later found several largeasteroids.^[20]

Piazzi's book "Della scoperta del nuovo pianeta Cerere Ferdinandea" outlining the discovery of Ceres, dedicated the new "planet" toFerdinand I of the Two Sicilies

One of the astronomers selected for the search was Giuseppe Piazziat the Academy of Palermo, Sicily. Before receiving his invitation to join the group, Piazzi discovered Ceres on January 1, 1801.^[21] He was searching for "the 87th [star] of the Catalogue of the Zodiacal stars of Mr la Caille", but found that "it was preceded by another".^[19]Instead of a star, Piazzi had found a moving star-like object, which he first thought was a comet.^[22] Piazzi observed Ceres a total of 24 times, the final time on February 11, 1801, when illness interrupted his observations. He announced his discovery on January 24, 1801 in letters to only two fellow astronomers, his compatriot Barnaba Orianiof Milan and Bode of Berlin.^[23] He reported it as a comet but "since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet".^[19] In April, Piazzi sent his complete observations to Oriani, Bode, andJerome Lalande in Paris. The information was published in the September 1801 issue of the Monatliche Correspondenz.^[22]

By this time, the apparent position of Ceres had changed (mostly due to Earth's orbital motion), and was too close to the Sun's glare for other astronomers to confirm‎ Piazzi's observations. Toward the end of the year, Ceres should have been visible again, but after such a long time it was difficult to predict its exact position. To recover Ceres, Carl Friedrich Gauss, then 24 years old, developed an efficient method of orbit determination.^[22] In only a few weeks, he predicted the path of Ceres and sent his results to von Zach. On December 31, 1801, von Zach and Heinrich W. M. Olbers found Ceres near the predicted position and thus recovered it.^[22]

The early observers were only able to calculate the size of Ceres to within about an order of magnitude. Herschel underestimated its size as 260 km in 1802, whereas in 1811 Johann Hieronymus Schroter overestimated it as 2,613 km.^[24][25]

Names[edit]

Piazzi originally suggested the name Cerere Ferdinandea for his discovery, after the goddess Ceres(Roman goddess of agriculture, Cerere in Italian) and King Ferdinand of Sicily.^[19][22] "Ferdinandea", however, was not acceptable to other nations and was dropped. Ceres was called Hera for a short time in Germany.^[26] In Greece, it is called Demeter (Δήμητρα), after the Greek equivalent of the Roman Cerēs;^[a] in English, that name is used for the asteroid 1108 Demeter.

The regular adjectival forms of the name are Cererian and Cererean,^[27] derived from the Latingenitive Cereris,^[3] but Ceresian is occasionally seen for the goddess (as in the sickle-shapedCeresian Lake), as is the shorter form Cerean.

The old astronomical symbol of Ceres is a sickle, ⟨⚳⟩ (),^[28] similar to Venus's symbol ⟨♀⟩ but with a break in the circle, with a variant ⟨⟩ reversed under the influence of the initial letter 'C' of 'Cerium'. This was later replaced with the generic asteroid symbol of a numbered disk, ⟨①⟩.^[22][29]

The chemical element cerium, discovered in 1803, was named after Ceres.^[30][b] In the same year another element was also initially named after Ceres, but when cerium was named its discoverer changed the name to palladium, after the second asteroid, 2 Pallas.^[32]

Classification[edit]

Ceres (bottom left), the Moonand the Earth, shown to scale

The categorization of Ceres has changed more than once and has been the subject of some disagreement.Johann Elert Bode believed Ceres to be the "missing planet" he had proposed to exist between Mars andJupiter, at a distance of 419 million km (2.8 AU) from the Sun.^[19] Ceres was assigned a planetary symbol, andremained listed as a planet in astronomy books and tables (along with 2 Pallas, 3 Juno and 4 Vesta) for half a century.^[19][22][33]

As other objects were discovered in the neighborhood of Ceres, it was realized that Ceres represented the first of a new class of objects.^[19] In 1802, with the discovery of 2 Pallas, William Herschel coined the termasteroid ("star-like") for these bodies,^[33] writing that "they resemble small stars so much as hardly to be distinguished from them, even by very good telescopes".^[34] As the first such body to be discovered, Ceres was given the designation 1 Ceres under the modern system of asteroid numbering.^[33]

First asteroid image from Mars: Ceres and Vesta viewed byCuriosity (20 April 2014).

The 2006 debate surrounding Pluto and what constitutes a 'planet' led to Ceres being considered for reclassification as a planet.^[35][36] A proposal before the International Astronomical Union for the definition of a planet would have defined a planet as "a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet".^[37] Had this resolution been adopted, it would have made Ceres the fifth planet in order from the Sun.^[38] This never happened, however, and on 24 August 2006 a modified definition was adopted, carrying the additional requirement that a planet must have "cleared the neighborhood around its orbit". By this definition, Ceres is not a planet because it does not dominate its orbit, sharing it as it does with the thousands of other asteroids in the asteroid belt and constituting only about a third of the mass of the belt. Bodies which met the first proposed definition but not the second, such as Ceres, were instead classified as dwarf planets (planetoids).

It is sometimes assumed that Ceres has been reclassified as a dwarf planet, and that it is therefore no longer considered an asteroid. For example, a news update at Space.com spoke of "Pallas, the largest asteroid, and Ceres, the dwarf planet formerly classified as an asteroid",^[39]whereas an IAU question-and-answer posting states, "Ceres is (or now we can say it was) the largest asteroid", though it then speaks of "other asteroids" crossing Ceres's path and otherwise implies that Ceres is still considered an asteroid.^[40] The Minor Planet Center notes that such bodies may have dual designations.^[41] The 2006 IAU decision that classified Ceres as a dwarf planet never addressed whether it is or is not an asteroid, as indeed the IAU has never defined the word 'asteroid' at all, preferring the term 'minor planet' until 2006, and 'small Solar System body' and 'dwarf planet' after 2006. Lang (2011) comments, "The [IAU has] added a new designation to Ceres, classifying it as a dwarf planet. ... By [its] definition, Eris, Haumea, Makemake and Pluto, as well as the largest asteroid, 1 Ceres, are all dwarf planets", and describes it elsewhere as "the dwarf planet–asteroid 1 Ceres".^[42] NASA continues to refer to Ceres as an asteroid, saying in a 2011 press announcement that "Dawn will orbit two of the largest asteroids in the Main Belt",^[43] as do various academic textbooks.^[44][45]

Physical characteristics[edit]

Sizes of the first ten main-belt objects discovered profiled against theMoon. Ceres is far left (1).

Hubble Space Telescope images of Ceres, taken in 2003–04 with a resolution of about 30 km. The nature of the bright spot is uncertain.^[46]

Ceres is the largest object in the asteroid belt.^[13] The mass of Ceres has been determined by analysis of the influence it exerts on smaller asteroids. Results differ slightly between researchers.^[47]The average of the three most precise values as of 2008 is 9.4×10²⁰ kg.^[8][47] With this mass Ceres comprises about a third of the estimated total 3.0 ± 0.2×10²¹ kg mass of the asteroid belt,^[48]which is in turn about 4% of the mass of the Moon. The mass of Ceres is sufficient to give it a nearly spherical shape in hydrostatic equilibrium.^[7] Among Solar System bodies, Ceres is intermediate in size between the smaller Orcus and 2002 MS₄ and the largerTethys. The surface area is approximately equal to the land area of India or Argentina.^[49]

Internal structure[edit]

Ceres's oblateness is inconsistent with an undifferentiated body, which indicates that it consists of a rocky core overlain with an icy mantle.^[7] This 100-kilometer-thick mantle (23%–28% of Ceres by mass; 50% by volume)^[50] contains 200 million cubic kilometers of water, which is more than the amount of fresh water on Earth.^[51] This result is supported by the observations made by the Keck telescope in 2002 and by evolutionary modeling.^[8][52] 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.^[8]

Alternatively, the shape and dimensions of Ceres may be explained by an interior that is porous and either partially differentiated or completely undifferentiated. The presence of a layer of rock on top of ice would be gravitationally unstable. If any of the rock deposits sank into a layer of differentiated ice, salt deposits would be formed. Such deposits have not been detected. Thus it is possible that Ceres does not contain a large ice shell, but was instead formed from low-density asteroids with an aqueous component. The decay of radioactive isotopes may not have produced sufficient heat to cause differentiation.^[53]

Surface[edit]

The surface composition of Ceres is broadly similar to that of C-type asteroids.^[13] Some differences do exist. The ubiquitous features of the Cererian IR spectra are those of hydrated materials, which indicate the presence of significant amounts of water in the interior. Other possible surface constituents include iron-rich clay minerals (cronstedtite) and carbonate minerals (dolomite and siderite), which are common minerals incarbonaceous chondrite meteorites.^[13] The spectral features of carbonates and clay minerals are usually absent in the spectra of other C-type asteroids.^[13] Sometimes Ceres is classified as a G-type asteroid.^[54]

The Cererian surface is relatively warm. The maximum temperature with the Sun overhead was estimated from measurements to be 235 K (about −38 °C, −36 °F) on 5 May 1991.^[17]

Diagram showing a possible internal structure of Ceres

Only a few Cererian surface features have been unambiguously detected. High-resolution ultravioletHubble Space Telescope images taken in 1995 showed a dark spot on its surface, which was nicknamed "Piazzi" in honor of the discoverer of Ceres.^[54] This was thought to be a crater. Later near-infrared images with a higher resolution taken over a whole rotation with the Keck telescope usingadaptive optics showed several bright and dark features moving with Ceres's rotation.^[8][55] Two dark features had circular shapes and are presumably craters; one of them was observed to have a bright central region, whereas another was identified as the "Piazzi" feature.^[8][55] More recent visible-lightHubble Space Telescope images of a full rotation taken in 2003 and 2004 showed 11 recognizable surface features, the natures of which are currently unknown.^[12][56] One of these features corresponds to the "Piazzi" feature observed earlier.^[12]

These last observations also determined that the north pole of Ceres points in the direction of right ascension 19 h 24 min (291°), declination +59°, in the constellation Draco. This means that Ceres'saxial tilt is very small—about 3°.^[7][12]

Atmosphere[edit]

There are indications that Ceres may have a tenuous atmosphere and water frost on the surface.^[57] Surface water ice is unstable at distances less than 5 AU from the Sun,^[58] so it is expected to sublime if it is exposed directly to solar radiation. Water ice can migrate from the deep layers of Ceres to the surface, but escapes in a very short time. As a result, it is difficult to detect water vaporization. Water escaping from polar regions of Ceres was possibly observed in the early 1990s but this has not been unambiguously demonstrated. It may be possible to detect escaping water from the surroundings of a fresh impact crater or from cracks in the subsurface layers of Ceres.^[8] Ultraviolet observations by the IUE spacecraft detected statistically significant amounts of hydroxide ions near the Cererean north pole, which is a product of water-vapor dissociation by ultraviolet solar radiation.^[57]

In early 2014, using data from the Herschel Space Observatory, it was discovered that there are several localized (not more than 60 km in diameter) mid-latitude sources of water vapor on Ceres, which each give off about 10²⁶ molecules (or 3  kg) of water per second.^[59][60][c] Two potential source regions, designated Piazzi (123°E, 21°N) and Region A (231°E, 23°N), have been visualized in the near infrared as dark areas (Region A also has a bright center) by the W. M. Keck Observatory. Possible mechanisms for the vapor release are sublimation from about 0.6 km² of exposed surface ice, or cryovolcanic eruptions resulting from radiogenic internal heat.^[59] Surface sublimation would be expected to decline as Ceres recedes from the Sun in its eccentric orbit, while internally powered emissions should not be affected by orbital position. The limited data available are more consistent with cometary-style sublimation.^[59] The spacecraft Dawn will arrive at Ceres in 2015 as it approachesaphelion, which may constrain its ability to observe this phenomenon.^[59]

Potential for extraterrestrial life[edit]

Although not as actively discussed as a potential home for extraterrestrial life as Mars, Titan or Europa, the presence of water ice has led to speculation that life may exist there,^[63][64][65] and that hypothesized ejecta could have come from Ceres to Earth.^[66]

Orbit[edit]

Orbit of Ceres

Ceres follows an orbit between Mars and Jupiter, within the asteroid belt, with a period of 4.6 Earth years.^[5] The orbit is moderately inclined (i = 10.6° compared to 7° for Mercury and 17° for Pluto) and moderately eccentric (e = 0.08 compared to 0.09 for Mars).^[5]

The diagram illustrates the orbits of Ceres (blue) and several planets (white and gray). The segments of orbits below the ecliptic are plotted in darker colors, 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 theperihelia (q) and aphelia (Q) of Ceres and Mars. The perihelion of Mars is on the opposite side of the Sun from those of Ceres and several of the large main-belt asteroids, including 2 Pallas and 10 Hygiea. The bottom diagram is a side view showing the inclination of the orbit of Ceres compared to the orbits of Mars and Jupiter.

Proper (long-term mean) orbital elements compared to osculating (instant) orbital elements for Ceres:

Element type	a (in AU)	e	i	Period (in days)
Proper[6]	2.7671	0.116198	9.647435	1681.60
Osculating[5] (Epoch 2010-Jul-23)	2.7653	0.079138	10.586821	1679.66
Difference	0.0018	0.03706	0.939386	1.94

In the past, Ceres had been considered a member of anasteroid family.^[67] These groupings of asteroids share similar proper orbital elements, which may indicate a common origin through an asteroid collision some time in the past. Ceres was found to have spectral properties different from other members of the family, and so this grouping is now called the Gefion family, named after the next-lowest-numbered family member, 1272 Gefion.^[67]Ceres appears to be merely an interloper in its own family, coincidentally having similar orbital elements but not a common origin.^[68]

The rotational period of Ceres (the Cererian day) is 9 hours and 4 minutes.^[69]

Ceres is in a near-1:1 mean-motion orbital resonance with Pallas (their orbital periods differ by 0.3%).^[70] However, a true resonance between the two would be unlikely; due to their small masses relative to their large separations, such relationships among asteroids are very rare.^[71]

Transits of planets from Ceres[edit]

Mercury, Venus, Earth, and Mars can all appear to cross the Sun, or transit it, from a vantage point at Ceres. The most common transits are those of Mercury, which usually happen every few years, most recently in 2006 and 2010. The corresponding dates are 1953 and 2051 for Venus, 1814 and 2081 for Earth, and 767 and 2684 for Mars.^[72]

Origin and evolution[edit]

Ceres is probably a surviving protoplanet (planetary embryo), which formed 4.57 billion years ago in the asteroid belt.^[52] Although the majority ofinner Solar System protoplanets (including all lunar- to Mars-sized bodies) either merged with other protoplanets to form terrestrial planets or were ejected from the Solar System by Jupiter,^[73] Ceres is believed to have survived relatively intact.^[52] An alternative theory proposes that Ceres formed in the Kuiper belt and later migrated to the asteroid belt.^[74] Another possible protoplanet, Vesta, is less than half the size of Ceres; it suffered a major impact after solidifying, losing ~1% of its mass.^[75]

The geological evolution of Ceres was dependent on the heat sources available during and after its formation: friction from planetesimal accretion, and decay of various radionuclides (possibly including short-lived elements like ²⁶Al). These are thought to have been sufficient to allow Ceres to differentiate into a rocky core and icy mantle soon after its formation.^[12][52] This process may have caused resurfacing by water volcanism andtectonics, erasing older geological features.^[52] Due to its small size, Ceres would have cooled early in its existence, causing all geological resurfacing processes to cease.^[52][76] Any ice on the surface would have gradually sublimated, leaving behind various hydrated minerals like clay minerals and carbonates.^[13]

Today, Ceres appears to be a geologically inactive body, with a surface sculpted only by impacts.^[12] The presence of significant amounts of water ice in its composition^[7] raises the possibility that Ceres has or had a layer of liquid water in its interior.^[52][76] This hypothetical layer is often called an ocean.^[13] If such a layer of liquid water exists, it is believed to be located between the rocky core and ice mantle like that of the theorized ocean on Europa.^[52] The existence of an ocean is more likely if solutes (i.e. salts), ammonia, sulfuric acid or other antifreeze compounds are dissolved in the water.^[52]

When Ceres has an opposition near the perihelion, it can reach a visual magnitude of +6.7.^[14] 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. Ceres was at its brightest (6.73) on December 18, 2012.^[15] The only other asteroids that can reach a similarly bright magnitude are 4 Vesta, and, during rare oppositions near perihelion, 2 Pallas and 7 Iris.^[77] At a conjunction Ceres has a magnitude of around +9.3, which corresponds to the faintest objects visible with 10×50 binoculars. It can thus be seen with binoculars whenever it is above the horizon of a fully dark sky.

Some notable observational milestones for Ceres include:

• An occultation of a star by Ceres observed in Mexico, Florida and across the Caribbean on November 13, 1984.^[78]
• Ultraviolet Hubble Space Telescope images with 50 km resolution taken on June 25, 1995.^[54][79]
• Infrared images with 30 km resolution taken with the Keck telescope in 2002 using adaptive optics.^[55]
• Visible light images with 30 km resolution (the best to date) taken using Hubble in 2003 and 2004.^[12][56]
• In 2014, Ceres was found to have an atmosphere with water vapor, confirmed by the Herschel space telescope.^[80]

Occultations[edit]

On December 22, 2012, 1 Ceres occulted the star TYC 1865-00446-1 over parts of Japan, Russia, and China.^[81] Ceres's brightness was magnitude 6.9 and the star, 12.2.^[81]

Exploration[edit]

Artistic montage of Dawn firing itsion rocket engine, with conjectural Vesta, Ceres (right), and asteroid field.

No space probe has visited Ceres, though one is on its way.

Radio signals from spacecraft in orbit around and on the surface of Mars have been used to estimate the mass of Ceres from its perturbations on the motion of Mars.^[48] On April 20, 2014, Mars rover Curiositysnapped the first ever photos of asteroids from the Martian surface, including Ceres and Vesta.^[82]

The spacecraft Dawn, launched by NASA in 2007, is continuing on to Ceres after having orbited asteroid 4 Vesta from July 15, 2011 to September 5, 2012.^[83] Dawn is scheduled to enter Ceres orbit in late March or early April 2015, several months prior to the arrival of New Horizons at Pluto.

Dawn's mission profile calls for it to enter orbit around Ceres at an altitude of 5,900 km. The spacecraft will reduce its orbital distance to 1,300 km after five months of study, and then down to 700 km after another five months.^[84] The spacecraft instrumentation includes a framing camera, a visual and infraredspectrometer, and a gamma-ray and neutron detector. These instruments will examine Ceres's shape and elemental composition.^[85]

The Chinese Space Agency is in process of designing a sample retrieval‎ mission from Ceres that would take place during the 2020s.^[86]

See also[edit]

Solar System portal

Book: Solar System

• Ceres in fiction
• Colonization of Ceres
• Former classification of planets

Notes[edit]

1. Jump up^ All other languages but one use a variant of Ceres/Cerere: Russian Tserera, Persian Seres, Japanese Keresu. The exception is Chinese, which uses 'grain-god(dess) star' (穀神星 gǔshenxīng). Note that this is unlike the goddess Ceres, where Chinese does use the Latin name (刻瑞斯 keruisī).
2. Jump up^ In 1807 Klaproth tried to change the name to the more etymologically justified "cererium", but it did not take.^[31]
3. Jump up^ This emission rate is modest compared to those calculated for the tidally driven plumes of Enceladus (a smaller body) and Europa (a larger body), 200 kg/s^[61] and 7000 kg/s,^[62] respectively.

References[edit]

1. Jump up^ Parker, J.; Thomas, P.; McFadden, L.; Mutchler, M. and Levay, Z."Color View of Ceres". NASA.
2. Jump up^ Schmadel, Lutz (2003). Dictionary of minor planet names (5th ed.). Germany: Springer. p. 15. ISBN 978-3-540-00238-3.
3. ^ Jump up to:^a b Simpson, D. P. (1979). Cassell's Latin Dictionary (5th ed.). London: Cassell Ltd. p. 883. ISBN 978-0-304-52257-6.
4. Jump up^ "The MeanPlane (Invariable plane) of the Solar System passing through the barycenter". 3 April 2009. Archived from the original on 14 May 2009. Retrieved 10 April 2009. (produced with Solex 10 written by Aldo Vitagliano; see also Invariable plane)
5. ^ Jump up to:^a b c d "1 Ceres". JPL Small-Body Database Browser. Archived from the original on 4 August 2012. Retrieved 8 January 2015.
6. ^ Jump up to:^a b "AstDyS-2 Ceres Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. Archived from the original on 5 October 2011. Retrieved 1 October 2011.
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8. ^ Jump up to:^{a b c d e f g} 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.
9. ^ Jump up to:^a b c "Ceres". NASA fact sheet. NASA. 2014-04-02. Retrieved2014-05-04.
10. Jump up^ Calculated based on the known parameters
11. Jump up^ Chamberlain, Matthew A.; Sykes, Mark V.; Esquerdo, Gilbert A. (2007). "Ceres lightcurve analysis – Period determination". Icarus 188 (2): 451–456. Bibcode:2007Icar..188..451C.doi:10.1016/j.icarus.2006.11.025.
12. ^ Jump up to:^{a b c d e f g h} Li, Jian-Yang; McFadden, Lucy A.; Parker, Joel Wm. (2006). "Photometric analysis of 1 Ceres and surface mapping from HST observations". Icarus 182 (1): 143–160.Bibcode:2006Icar..182..143L. doi:10.1016/j.icarus.2005.12.012. Retrieved 8 December 2007.
13. ^ Jump up to:^{a b c d e f g} 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. Retrieved 8 December 2007.
14. ^ Jump up to:^a b 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.
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17. ^ Jump up to:^a b Saint-Pe, O.; Combes, N.; Rigaut F. (1993). "Ceres surface properties by high-resolution imaging from Earth". Icarus 105 (2): 271–281. Bibcode:1993Icar..105..271S. doi:10.1006/icar.1993.1125.
18. Jump up^ "Ceres". Dictionary.com. Random House, Inc. Archived from the original on 5 October 2011. Retrieved 26 September 2007.
19. ^ Jump up to:^{a b c d e f g h i j k} Hoskin, Michael (26 June 1992). "Bode's Law and the Discovery of Ceres". Observatorio Astronomico di Palermo "Giuseppe S. Vaiana". Archived from the original on 18 January 2010. Retrieved5 July 2007.
20. ^ Jump up to:^a b c d Hogg, Helen Sawyer (1948). "The Titius-Bode Law and the Discovery of Ceres". Journal of the Royal Astronomical Society of Canada242: 241–246. Bibcode:1948JRASC..42..241S.
21. Jump up^ Hoskin, Michael (1999). The Cambridge Concise History of Astronomy. Cambridge University press. pp. 160–161. ISBN 978-0-521-57600-0.
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23. Jump up^ Clifford J. Cunningham (2001). The first asteroid: Ceres, 1801–2001. Star Lab Press. ISBN 978-0-9708162-1-4.
24. Jump up^ Hilton, James L. "Asteroid Masses and Densities" (PDF). U.S. Naval Observatory. Retrieved 23 June 2008.
25. Jump up^ Hughes, D. W. (1994). "The Historical Unravelling of the Diameters of the First Four Asteroids". R.A.S. Quarterly Journal 35 (3): 331.Bibcode:1994QJRAS..35..331H.(Page 335)
26. Jump up^ Fodera Serio, G.; Manara, A.; Sicoli, P. (2002). "Giuseppe Piazzi and the Discovery of Ceres". In W. F. Bottke Jr., A. Cellino, P. Paolicchi, and R. P. Binzel. Asteroids III (PDF). Tucson, Arizona: University of Arizona Press. pp. 17–24. Retrieved 25 June 2009.
27. Jump up^ Rupke, Jorg (2011). A Companion to Roman Religion. John Wiley and Sons. pp. 90–. ISBN 978-1-4443-4131-7.
28. Jump up^ Unicode value U+26B3
29. Jump up^ Gould, B. A. (1852). "On the symbolic notation of the asteroids".Astronomical Journal 2 (34): 80. Bibcode:1852AJ......2...80G.doi:10.1086/100212.
30. Jump up^ "Cerium: historical information". Adaptive Optics. Retrieved 27 April2007.
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34. Jump up^ Herschel, William (6 May 1802). "Observations on the two lately discovered celestial Bodies.". Archived from the original on 5 October 2011.
35. Jump up^ Battersby, Stephen (16 August 2006). "Planet debate: Proposed new definitions". New Scientist. Archived from the original on 5 October 2011. Retrieved 27 April 2007.
36. Jump up^ Connor, Steve (16 August 2006). "Solar system to welcome three new planets". NZ Herald. Archived from the original on 5 October 2011. Retrieved 27 April 2007.
37. Jump up^ Gingerich, Owen; et al. (16 August 2006). "The IAU draft definition of "Planet" and "Plutons"". IAU. Archived from the original on 5 October 2011. Retrieved 27 April 2007.
38. Jump up^ "The IAU Draft Definition of Planets And Plutons". SpaceDaily. 16 August 2006. Archived from the original on 18 January 2010. Retrieved27 April 2007.
39. Jump up^ Geoff Gaherty, "How to Spot Giant Asteroid Vesta in Night Sky This Week", 3 August 2011 How to Spot Giant Asteroid Vesta in Night Sky This Week | Asteroid Vesta Skywatching Tips | Amateur Astronomy, Asteroids & Comets | Space.com Archived 5 October 2011 atWebCite
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41. Jump up^ Spahr, T. B. (7 September 2006). "MPEC 2006-R19: EDITORIAL NOTICE". Minor Planet Center. Archived from the original on 5 October 2011. Retrieved 31 January 2008. the numbering of "dwarf planets" does not preclude their having dual designations in possible separate catalogues of such bodies.
42. Jump up^ Lang, Kenneth (2011). The Cambridge Guide to the Solar System. Cambridge University Press. pp. 372, 442.
43. Jump up^ NASA/JPL, Dawn Views Vesta, 2011 Aug 02 Archived 5 October 2011 at WebCite
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45. Jump up^ Mann; Nakamura; Mukai (2009). Small bodies in planetary systems. Lecture Notes in Physics 758. Springer-Verlag. ISBN 978-3-540-76934-7.
46. Jump up^ Parker, J.; Thomas, P. and McFadden, L. (7 September 2005). "Largest Asteroid May Be 'Mini Planet' with Water Ice". NASA. Archived from the original on 5 October 2011. Retrieved 6 June 2011.
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49. Jump up^ about forty percent that of Australia, a third the size of the US or Canada, 12× that of the UK
50. Jump up^ 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
51. Jump up^ 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.
52. ^ Jump up to:^{a b c d e f g h i} McCord, Thomas B. (2005). "Ceres: Evolution and current state". Journal of Geophysical Research 110 (E5): E05009.Bibcode:2005JGRE..11005009M. doi:10.1029/2004JE002244.
53. Jump up^ Zolotov, M. Yu. (2009). "On the Composition and Differentiation of Ceres". Icarus 204 (1): 183–193. Bibcode:2009Icar..204..183Z.doi:10.1016/j.icarus.2009.06.011.
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55. ^ Jump up to:^a b c "Keck Adaptive Optics Images the Dwarf Planet Ceres". Adaptive Optics. 11 October 2006. Archived from the original on 18 January 2010. Retrieved 27 April 2007.
56. ^ Jump up to:^a b "Largest Asteroid May Be 'Mini Planet' with Water Ice". HubbleSite. 7 September 2005. Archived from the original on 5 October 2011. Retrieved 16 August 2006.
57. ^ Jump up to:^a b A'Hearn, Michael F.; Feldman, Paul D. (1992). "Water vaporization on Ceres". Icarus 98 (1): 54–60. Bibcode:1992Icar...98...54A.doi:10.1016/0019-1035(92)90206-M.
58. Jump up^ Jewitt, D; Chizmadia, L.; Grimm, R.; Prialnik, D (2007). "Water in the Small Bodies of the Solar System". In Reipurth, B.; Jewitt, D.; Keil, K.Protostars and Planets V (PDF). University of Arizona Press. pp. 863–878. ISBN 0-8165-2654-0.
59. ^ Jump up to:^a b c d Kuppers, M.; O'Rourke, L.; Bockelee-Morvan, D.; Zakharov, V.; Lee, S.; Von Allmen, P.; Carry, B.; Teyssier, D.; Marston, A.; Muller, T.; Crovisier, J.; Barucci, M. A.; Moreno, R. (2014-01-23). "Localized sources of water vapour on the dwarf planet (1) Ceres". Nature 505 (7484): 525–527. Bibcode:2014Natur.505..525K. doi:10.1038/nature12918.ISSN 0028-0836. PMID 24451541.
60. Jump up^ Campins, H.; Comfort, C. M. (2014-01-23). "Solar system: Evaporating asteroid". Nature 505 (7484): 487–488. doi:10.1038/505487a.PMID 24451536. edit
61. Jump up^ Hansen, C. J.; Esposito, L.; Stewart, A. I.; Colwell, J.; Hendrix, A.; Pryor, W.; Shemansky, D.; West, R. (2006-03-10). "Enceladus' Water Vapor Plume". Science 311 (5766): 1422–1425.doi:10.1126/science.1121254. PMID 16527971. edit
62. Jump up^ Roth, L.; Saur, J.; Retherford, K. D.; Strobel, D. F.; Feldman, P. D.; McGrath, M. A.; Nimmo, F. (26 November 2013). "Transient Water Vapor at Europa's South Pole". Science 343 (6167): 171–174.doi:10.1126/science.1247051. PMID 24336567. Retrieved2014-01-26. edit
63. Jump up^ O'Neill, Ian (5 March 2009). "Life on Ceres: Could the Dwarf Planet be the Root of Panspermia". Universe Today. Retrieved 30 January 2012.
64. Jump up^ Catling, David C. (2013). Astrobiology: A Very Short Introduction. Oxford: Oxford University Press. p. 99. ISBN 0-19-958645-4.
65. Jump up^ Is there life on Ceres? Dwarf planet spews water vapor into space.(22 January 2014)
66. Jump up^ "Glaciopanspermia: Seeding the Terrestrial Planets with Life?" Joop M. Houtkooper, Institute for Psychobiology and Behavioral Medicine, Justus-Liebig-University, Giessen, Germany
67. ^ Jump up to:^a b Cellino, A. et al. (2002). "Spectroscopic Properties of Asteroid Families". Asteroids III (PDF). University of Arizona Press. pp. 633–643 (Table on p. 636). Bibcode:2002aste.conf..633C.
68. Jump up^ Kelley, M. S.; Gaffey, M. J. (1996). "A Genetic Study of the Ceres (Williams #67) Asteroid Family". Bulletin of the American Astronomical Society 28: 1097. Bibcode:1996BAAS...28R1097K.
69. Jump up^ Williams, David R. (2004). "Asteroid Fact Sheet". Archived from the original on 18 January 2010.
70. Jump up^ Kovačević, A. B. (2011). "Determination of the mass of Ceres based on the most gravitationally efficient close encounters". Monthly Notices of the Royal Astronomical Society 419 (3): 2725–2736. arXiv:1109.6455.Bibcode:2012MNRAS.419.2725K. doi:10.1111/j.1365-2966.2011.19919.x.
71. Jump up^ Christou, A. A. (2000). "Co-orbital objects in the main asteroid belt".Astronomy and Astrophysics 356: L71–L74.Bibcode:2000A&A...356L..71C.
72. Jump up^ "Solex numbers generated by Solex". Archived from the original on 29 April 2009. Retrieved 3 March 2009.
73. Jump up^ Petit, Jean-Marc; Morbidelli, Alessandro (2001). "The Primordial Excitation and Clearing of the Asteroid Belt" (PDF). Icarus 153 (2): 338–347. Bibcode:2001Icar..153..338P. doi:10.1006/icar.2001.6702. Retrieved 25 June 2009.
74. Jump up^ About a 10% chance of the asteroid belt acquiring a Ceres-mass KBO. 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
75. Jump up^ Thomas, Peter C.; Binzel, Richard P.; Gaffey, Michael J.; et al. (1997). "Impact Excavation on Asteroid 4 Vesta: Hubble Space Telescope Results". Science 277 (5331): 1492–1495.Bibcode:1997Sci...277.1492T. doi:10.1126/science.277.5331.1492.
76. ^ Jump up to:^a b Castillo-Rogez, J. C.; McCord, T. B.; and Davis, A. G. (2007)."Ceres: evolution and present state" (PDF). Lunar and Planetary Science. XXXVIII: 2006–2007. Retrieved 25 June 2009.
77. Jump up^ Martinez, Patrick, The Observer's Guide to Astronomy, page 298. Published 1994 by Cambridge University Press
78. Jump up^ Millis, L. R.; Wasserman, L. H.; Franz, O. Z.; et al. (1987). "The size, shape, density, and albedo of Ceres from its occultation of BD+8°471".Icarus 72 (3): 507–518. Bibcode:1987Icar...72..507M.doi:10.1016/0019-1035(87)90048-0.
79. Jump up^ "Observations reveal curiosities on the surface of asteroid Ceres".Archived from the original on 5 October 2011. Retrieved 16 August2006.
80. Jump up^ "Water Detected on Dwarf Planet Ceres". Science.nasa.gov. Retrieved 24 January 2014.
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82. Jump up^ "Curiosity Snaps First Ever Photo of Asteroids From Mars". Discovery News. Discovery Channel. 2014-04-25. Retrieved 2014-05-04.
83. Jump up^ "NASA's Dawn Prepares for Trek Toward Dwarf Planet". NASA. Retrieved 1 September 2012.
84. Jump up^ Rayman, Marc (13 July 2006). "Dawn: mission description". UCLA—IGPP Space Physics Center. Archived from the original on 18 January 2010. Retrieved 27 April 2007.
85. Jump up^ Russel, C. T.; Capaccioni, F.; Coradini, A.; et al. (2006). "Dawn Discovery mission to Vesta and Ceres: Present status". Advances in Space Research 38 (9): 2043–2048. Bibcode:2006AdSpR..38.2043R.doi:10.1016/j.asr.2004.12.041.
86. Jump up^http://english.nssc.cas.cn/ns/NU/201410/W020141016603613379886.pdfChina's Deep-space Exploration to 2030 by Zou Yongliao Li Wei Ouyang Ziyuan Key Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, Beijing

External links[edit]

Wikimedia Commons has media related to Ceres (dwarf planet).

• Movie of one Ceres rotation (processed Hubble images)
• A simulation of the orbit of Ceres
• JPL Ephemeris
• How Gauss determined the orbit of Ceres from keplersdiscovery.com
• Hilton, James L. (1999). "U.S. Naval Observatory Ephemerides of the Largest Asteroids". The Astronomical Journal 117 (2): 1077.Bibcode:1999AJ....117.1077H. doi:10.1086/300728.

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