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40.09115982055664 142 WikiText2 |
20250 The 2006 debate surrounding Pluto and what constitutes a planet led to Ceres being considered for reclassification as a planet . 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 @-@ ... |
28.266462326049805 226 WikiText2 |
20251 Ceres is the largest object in the asteroid belt . 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 cla... |
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20252 = = Orbit = = |
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20253 Ceres follows an orbit between Mars and Jupiter , within the asteroid belt , with a period of 4 @.@ 6 Earth years . The orbit is moderately inclined ( i |
106.30113983154297 33 WikiText2 |
20254 = 10 @.@ 6 ° compared to 7 ° for Mercury and 17 ° for Pluto ) and moderately eccentric ( e = |
275.8310546875 25 WikiText2 |
20255 0 @.@ 08 compared to 0 @.@ 09 for Mars ) . |
256.4100036621094 16 WikiText2 |
20256 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 an... |
31.749908447265625 163 WikiText2 |
20257 Ceres was once thought to be a member of an asteroid family . The asteroids of this family share similar proper orbital elements , which may indicate a common origin through an asteroid collision some time in the past . Ceres was later found to have spectral properties different from other members of the family ... |
45.246761322021484 103 WikiText2 |
20258 = = = Resonances = = = |
202.57293701171875 7 WikiText2 |
20259 Ceres is in a near @-@ 1 : 1 mean @-@ motion orbital resonance with Pallas ( their proper orbital periods differ by 0 @.@ 2 % ) . 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 . Never... |
110.06743621826172 106 WikiText2 |
20260 = = = Transits of planets from Ceres = = = |
294.36773681640625 11 WikiText2 |
20261 Mercury , Venus , Earth , and Mars can all appear to cross the Sun , or transit it , from a vantage point on Ceres . The most common transits are those of Mercury , which usually happen every few years , most recently in 2006 and 2010 . The most recent transit of Venus was in 1953 , and the next will be in 2051 ... |
28.351408004760742 89 WikiText2 |
20262 = = Rotation and axial tilt = = |
123.48329162597656 8 WikiText2 |
20263 The rotation period of Ceres ( the Cererian day ) is 9 hours and 4 minutes . It has a small axial tilt of 4 ° . This is nevertheless large enough for Ceres 's polar regions to contain permanently shadowed craters that are expected to act as cold traps and accumulate water ice over time , similar to the situation... |
75.1907958984375 102 WikiText2 |
20264 = = Geology = = |
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20265 Ceres has a mass of 9 @.@ 39 × 1020 kg as determined from the Dawn spacecraft . With this mass Ceres comprises approximately a third of the estimated total 3 @.@ 0 ± 0 @.@ 2 × 1021 kg mass of the asteroid belt , which is in turn approximately 4 % of the mass of the Moon . Ceres is massive enough to give it a nea... |
36.77360153198242 115 WikiText2 |
20266 = = = Surface = = = |
215.51832580566406 7 WikiText2 |
20267 The surface composition of Ceres is broadly similar to that of C @-@ type asteroids . Some differences do exist . The ubiquitous features in Ceres ' IR spectrum are those of hydrated materials , which indicate the presence of significant amounts of water in its interior . Other possible surface constituents incl... |
32.340206146240234 119 WikiText2 |
20268 Ceres ' surface is relatively warm . The maximum temperature with the Sun overhead was estimated from measurements to be 235 K ( approximately − 38 ° C , − 36 ° F ) on 5 May 1991 . Ice is unstable at this temperature . Material left behind by the sublimation of surface ice could explain the dark surface of Ceres... |
54.99950408935547 73 WikiText2 |
20269 = = = = Observations prior to Dawn = = = = |
135.25994873046875 12 WikiText2 |
20270 Prior to the Dawn mission , only a few surface features had been unambiguously detected on Ceres . High @-@ resolution ultraviolet Hubble Space Telescope images taken in 1995 showed a dark spot on its surface , which was nicknamed " Piazzi " in honor of the discoverer of Ceres . This was thought to be a crater .... |
38.371280670166016 178 WikiText2 |
20271 These last observations indicated that the north pole of Ceres pointed in the direction of right ascension 19 h 24 min ( 291 ° ) , declination + 59 ° , in the constellation Draco , resulting in an axial tilt of approximately 3 ° . Dawn later determined that the north polar axis actually points at right ascension... |
67.00435638427734 108 WikiText2 |
20272 = = = = Observations by Dawn = = = = |
131.80226135253906 11 WikiText2 |
20273 Dawn revealed a large number of craters with low relief , indicating that they lie over a relatively soft surface , probably of water ice . One crater , with extremely low relief , is 270 km ( 170 mi ) in diameter , reminiscent of large , flat craters on Tethys and Iapetus . An unexpectedly large number of Cerer... |
44.4336051940918 244 WikiText2 |
20274 On 9 December 2015 , NASA scientists reported that the bright spots on Ceres may be related to a type of salt , particularly a form of brine containing magnesium sulfate hexahydrite ( MgSO4 · 6H2O ) ; the spots were also found to be associated with ammonia @-@ rich clays . Another team thinks the salts are sodiu... |
58.69770431518555 63 WikiText2 |
20275 = = = Internal structure = = = |
153.7489013671875 8 WikiText2 |
20276 Ceres ' oblateness is consistent with a differentiated body , a rocky core overlain with an icy mantle . This 100 @-@ kilometer @-@ thick mantle ( 23 % – 28 % of Ceres by mass ; 50 % by volume ) contains up to 200 million cubic kilometers of water , which would be more than the amount of fresh water on Earth . T... |
45.840858459472656 241 WikiText2 |
20277 = = Atmosphere = = |
531.636474609375 5 WikiText2 |
20278 There are indications that Ceres may have a tenuous water vapor atmosphere outgassing from water ice on the surface . |
90.33477020263672 20 WikiText2 |
20279 Surface water ice is unstable at distances less than 5 AU from the Sun , 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 .... |
34.056434631347656 144 WikiText2 |
20280 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 approximately 1026 molecules ( or 3 kg ) of water per second . Two potential source region... |
42.74566650390625 206 WikiText2 |
20281 = = Origin and evolution = = |
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20282 Ceres is possibly a surviving protoplanet ( planetary embryo ) , which formed 4 @.@ 57 billion years ago in the asteroid belt . Although the majority of inner Solar System protoplanets ( including all lunar- to Mars @-@ sized bodies ) either merged with other protoplanets to form terrestrial planets or were ejec... |
37.737178802490234 141 WikiText2 |
20283 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 isotopes such as the cosmogenic nuclide aluminium @-@ 26 ) . These are thought to have been... |
50.45836639404297 134 WikiText2 |
20284 Today , Ceres appears to be a geologically inactive body , with a surface sculpted only by impacts . The presence of significant amounts of water ice in its composition raises the possibility that Ceres has or had a layer of liquid water in its interior . This hypothetical layer is often called an ocean . If suc... |
25.405162811279297 117 WikiText2 |
20285 = = Potential habitability = = |
1194.06103515625 6 WikiText2 |
20286 Although not as actively discussed as a potential home for microbial extraterrestrial life as Mars , Titan , Europa or Enceladus , there is evidence that Ceres ' icy mantle was once a watery subterranean ocean , and that has led to speculations that life could have existed there , and that hypothesized ejecta be... |
48.12065887451172 64 WikiText2 |
20287 = = Observation and exploration = = |
338.5795593261719 7 WikiText2 |
20288 = = = Observation = = = |
116.14639282226562 7 WikiText2 |
20289 When Ceres has an opposition near the perihelion , it can reach a visual magnitude of + 6 @.@ 7 . 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 it . Ceres was at its brightest ( 6 @.@ 73 ) on 18 De... |
40.09257507324219 152 WikiText2 |
20290 Some notable observations and milestones for Ceres include : |
618.5675048828125 9 WikiText2 |
20291 1984 November 13 : An occultation of a star by Ceres observed in Mexico , Florida and across the Caribbean . |
430.7060852050781 21 WikiText2 |
20292 1995 June 25 : Ultraviolet Hubble Space Telescope images with 50 @-@ kilometer resolution . |
392.7257995605469 17 WikiText2 |
20293 2002 : Infrared images with 30 km resolution taken with the Keck telescope using adaptive optics . |
130.69178771972656 17 WikiText2 |
20294 2003 and 2004 : Visible light images with 30 km resolution ( the best prior to the Dawn mission ) taken using Hubble . |
145.2613067626953 24 WikiText2 |
20295 2012 December 22 : Ceres occulted the star TYC 1865 @-@ 00446 @-@ 1 over parts of Japan , Russia , and China . Ceres ' brightness was magnitude 6 @.@ 9 and the star , 12 @.@ 2 . |
301.9616394042969 48 WikiText2 |
20296 2014 : Ceres was found to have an atmosphere with water vapor , confirmed by the Herschel space telescope . |
47.926963806152344 20 WikiText2 |
20297 2015 : The NASA Dawn spacecraft approached and orbited Ceres , sending detailed images and scientific data back to Earth . |
58.34946060180664 21 WikiText2 |
20298 = = = Exploration = = = |
215.84239196777344 7 WikiText2 |
20299 In 1981 , a proposal for an asteroid mission was submitted to the European Space Agency ( ESA ) . Named the Asteroidal Gravity Optical and Radar Analysis ( AGORA ) , this spacecraft was to launch some time in 1990 – 1994 and perform two flybys of large asteroids . The preferred target for this mission was Vesta ... |
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