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= = Atmosphere = =
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There are indications that Ceres may have a tenuous water vapor atmosphere outgassing from water ice on the surface .
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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 . Water... |
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 regions , de... |
= = Origin and evolution = =
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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 ejected fr... |
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 suffi... |
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 such a la... |
= = Potential habitability = =
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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 bearing ... |
= = Observation and exploration = =
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= = = Observation = = =
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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 December... |
Some notable observations and milestones for Ceres include :
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1984 November 13 : An occultation of a star by Ceres observed in Mexico , Florida and across the Caribbean .
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1995 June 25 : Ultraviolet Hubble Space Telescope images with 50 @-@ kilometer resolution .
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2002 : Infrared images with 30 km resolution taken with the Keck telescope using adaptive optics .
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2003 and 2004 : Visible light images with 30 km resolution ( the best prior to the Dawn mission ) taken using Hubble .
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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 .
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2014 : Ceres was found to have an atmosphere with water vapor , confirmed by the Herschel space telescope .
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2015 : The NASA Dawn spacecraft approached and orbited Ceres , sending detailed images and scientific data back to Earth .
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= = = Exploration = = =
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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 . AGOR... |
In the early 1990s , NASA initiated the Discovery Program , which was intended to be a series of low @-@ cost scientific missions . In 1996 , the program 's study team recommended as a high priority a mission to explore the asteroid belt using a spacecraft with an ion engine . Funding for this program remained problem... |
It was launched on 27 September 2007 , as the space mission to make the first visits to both Vesta and Ceres . On 3 May 2011 , Dawn acquired its first targeting image 1 @.@ 2 million kilometers from Vesta . After orbiting Vesta for 13 months , Dawn used its ion engine to depart for Ceres , with gravitational capture o... |
Dawn 's mission profile calls for it to study Ceres from a series of circular polar orbits at successively lower altitudes . It entered its first observational orbit ( " RC3 " ) around Ceres at an altitude of 13 @,@ 500 km on 23 April 2015 , staying for only approximately one orbit ( fifteen days ) . The spacecraft wi... |
Dawn 's arrival in a stable orbit around Ceres was delayed after , close to reaching Ceres , it was hit by a cosmic ray , making it take another , longer route around Ceres in back , instead of a direct spiral towards it .
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The Chinese Space Agency is designing a sample retrieval mission from Ceres that would take place during the 2020s .
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= = Maps = =
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= = = Map of quadrangles = = =
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The following imagemap of the dwarf planet Ceres is divided into 15 quadrangles . They are named after the first craters whose names the IAU approved in July 2015 . The map image ( s ) were taken by the Dawn space probe .
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= = Gallery = =
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= = = True @-@ color images = = =
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= = = Animations = = =
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= Skye =
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Skye , or the Isle of Skye ( / skaɪ / ; Scottish Gaelic : An t @-@ Eilean Sgitheanach or Eilean a ' Cheò ) , is the largest and most northerly major island in the Inner Hebrides of Scotland . The island 's peninsulas radiate from a mountainous centre dominated by the Cuillins , the rocky slopes of which provide some o... |
The island has been occupied since the Mesolithic period and its history includes a time of Norse rule and a long period of domination by Clan MacLeod and Clan Donald . The 18th @-@ century Jacobite risings led to the breaking up of the clan system and subsequent Clearances that replaced entire communities with sheep ... |
The main industries are tourism , agriculture , fishing and forestry . Skye is part of the Highland Council local government area . The island 's largest settlement is Portree , known for its picturesque harbour . There are links to various nearby islands by ferry and , since 1995 , to the mainland by a road bridge . ... |
= = Etymology = =
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The first written references to the island are Roman sources such as the Ravenna Cosmography , which refers to Scitis and Scetis , which can be found on a map by Ptolemy . One possible derivation comes from skitis , an early Celtic word for winged , which may describe how the island 's peninsulas radiate out from a mo... |
In the Norse sagas Skye is called Skíð , for example in the Hákonar saga Hákonarsonar and a skaldic poem in the Heimskringla from c . 1230 contains a line that translates as " the hunger battle @-@ birds were filled in Skye with blood of foemen killed " . The island was also referred to by the Norse as Skuy ( misty is... |
Eilean a ' Cheò , which means island of the mist ( a translation of the Norse name ) , is a poetic Gaelic name for the island .
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= = Geography = =
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At 1 @,@ 656 square kilometres ( 639 sq mi ) , Skye is the second @-@ largest island in Scotland after Lewis and Harris . The coastline of Skye is a series of peninsulas and bays radiating out from a centre dominated by the Cuillin hills ( Gaelic : An Cuiltheann ) . Malcolm Slesser suggested that its shape " sticks ou... |
There are marcasites black and white , resembling silver ore , near the village Sartle : there are likewise in the same place several stones , which in bigness , shape , & c . , resemble nutmegs , and many rivulets here afford variegated stones of all colours . The Applesglen near Loch @-@ Fallart has agate growing in... |
The Black Cuillin , which are mainly composed of basalt and gabbro , include twelve Munros and provide some of the most dramatic and challenging mountain terrain in Scotland . The ascent of Sgùrr a ' Ghreadaidh is one of the longest rock climbs in Britain and the Inaccessible Pinnacle is the only peak in Scotland that... |
The northern peninsula of Trotternish is underlain by basalt , which provides relatively rich soils and a variety of unusual rock features . The Kilt Rock is named after the tartan @-@ like patterns in the 105 metres ( 344 ft ) cliffs . The Quiraing is a spectacular series of rock pinnacles on the eastern side of the ... |
Beyond Loch Snizort to the west of Trotternish is the Waternish peninsula , which ends in Ardmore Point 's double rock arch . Duirinish is separated from Waternish by Loch Dunvegan , which contains the island of Isay . The loch is ringed by sea cliffs that reach 295 metres ( 967 ft ) at Waterstein Head . Oolitic loam ... |
= = = Towns and villages = = =
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Portree in the north at the base of Trotternish is the largest settlement ( estimated population 2 @,@ 264 in 2011 ) and is the main service centre on the island . Broadford , the location of the island 's only airstrip , is on the east side of the island and Dunvegan in the north @-@ west is well known for its castle... |
= = = Climate = = =
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The influence of the Atlantic Ocean and the Gulf Stream create a mild oceanic climate . Temperatures are generally cool , averaging 6 @.@ 5 ° C ( 43 @.@ 7 ° F ) in January and 15 @.@ 4 ° C ( 59 @.@ 7 ° F ) in July at Duntulm in Trotternish . Snow seldom lies at sea level and frosts are less frequent than on the mainla... |
= = History = =
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= = = Prehistory = = =
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A Mesolithic hunter @-@ gatherer site dating to the 7th millennium BC at An Corran in Staffin is one of the oldest archaeological sites in Scotland . Its occupation is probably linked to that of the rock shelter at Sand , Applecross , on the mainland coast of Wester Ross where tools made of a mudstone from An Corran h... |
Rubha an Dùnain , an uninhabited peninsula to the south of the Cuillin , has a variety of archaeological sites dating from the Neolithic onwards . There is a 2nd or 3rd millennium BC chambered cairn , an Iron Age promontory fort and the remains of other prehistoric settlement dating from the Bronze Age nearby . Loch n... |
= = = Early history = = =
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The late Iron Age inhabitants of the northern and western Hebrides were probably Pictish , although the historical record is sparse . Three Pictish symbol stones have been found on Skye and a fourth on Raasay . More is known of the kingdom of Dál Riata to the south ; Adomnán 's life of Columba , written shortly before... |
The Norse held sway throughout the Hebrides from the 9th century until after the Treaty of Perth in 1266 . However , apart from placenames , little remains of their presence on Skye in the written or archaeological record . Apart from the name " Skye " itself , all pre @-@ Norse placenames seem to have been obliterate... |
= = = Clans and Scottish rule = = =
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