Mercurio Ingles

Mercury (planet) 1

Mercury (planet)

Mercury  ☿

MESSENGER false-color image of Mercury

Designations

Pronunciation i/ˈmɜrkjəri/

Adjective Mercurian, Mercurial[1]

Orbital characteristics[2]

Epoch J2000

Aphelion •• 69,816,900 km• 0.466 697 AU

Perihelion •• 46,001,200 km•• 0.307 499 AU

Semi-major axis •• 57,909,100 km•• 0.387 098 AU

Eccentricity 0.205 630[3]

Orbital period • 87.969 1 d• (0.240 846 a)• 0.5 Mercury solar day

Synodic period 115.88 d[3]

Average orbital speed 47.87 km/s[3]

Mean anomaly 174.796°

Inclination • 7.005° to Ecliptic• 3.38° to Sun’s equator• 6.34° to Invariable plane[4]

Longitude of ascending node 48.331°

Argument of perihelion 29.124°

Satellites None

Physical characteristics

Mean radius • 2,439.7 ± 1.0 km[5][6]

•• 0.3829 Earths

Mercury (planet) 2

Flattening 0[6]

Surface area • 7.48×107 km2[5]

•• 0.147 Earths

Volume • 6.083×1010 km3[5]

•• 0.056 Earths

Mass • 3.3022×1023 kg[5]

•• 0.055 Earths

Mean density 5.427 g/cm3[5]

Equatorial surface gravity • 3.7 m/s2

• 0.38 g[5]

Escape velocity 4.25 km/s[5]

Sidereal rotationperiod

•• 58.646 day• 1407.5 h[5]

Equatorial rotation velocity 10.892 km/h (unknown operator: u'strong' m/s)

Axial tilt 2.11′ ± 0.1′[7]

North pole right ascension •• 18 h 44 min 2 s• 281.01°[3]

North pole declination 61.45°[3]

Albedo • 0.068 (Bond)[8]

• 0.142 (geom.)[8]

Surface temp.   0°N, 0°W [9]

   85°N, 0°W[9]

min mean max

100 K 340 K 700 K

80 K 200 K 380 K

Apparent magnitude −2.6[10] to 5.7[3][11]

Angular diameter 4.5" – 13"[3]

Atmosphere[3]

Surface pressure trace

Composition • 42% Molecular oxygen• 29.0% sodium• 22.0% hydrogen• 6.0% helium• 0.5% potassium• Trace amounts of argon, nitrogen, carbon dioxide, water

vapor, xenon, krypton and neon

Mercury is the innermost and smallest planet in the Solar System,[1] orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits. The perihelion of Mercury's orbit precesses around the Sun at an excess of 43 arcseconds per century, a phenomenon that was explained in the 20th century by Albert Einstein's General Theory of Relativity.[2] Mercury is bright when viewed from Earth, ranging from −2.3 to 5.7 in

Mercury (planet) 3

apparent magnitude, but is not easily seen as its greatest angular separation from the Sun is only 28.3°. SinceMercury is normally lost in the glare of the Sun, unless there is a solar eclipse it can be viewed only for shortintervals before sunrise when it is near its maximum western elongation, or after sunset when near its maximumeastern elongation. At relatively high latitudes such as those of many European and North American populationcentres, it is even then near the horizon and obscured in a relatively bright twilit sky. However, at tropical andsubtropical latitudes, Mercury is more easily seen because of two effects. (i) the Sun ascends above the horizon moresteeply at sunrise and descends more steeply at sunset, so the twilight period is shorter, and (ii) at the right times ofyear, the Ecliptic intersects the horizon at a very steep angle, meaning that Mercury can be relatively high (altitudeup to 28°) in a fully dark sky. Such conditions can pertain, for instance, after sunset near the Spring Equinox, inMarch/April for the southern USA and in September/October for South Africa and Australasia. Conversely,pre-sunrise viewing is easiest near the Autumn Equinox.Comparatively little is known about Mercury; ground-based telescopes reveal only an illuminated crescent withlimited detail. The first of two spacecraft to visit the planet was Mariner 10, which mapped about 45% of its surfacefrom 1974 to 1975. The second is the MESSENGER spacecraft, which attained orbit around Mercury on March 17,2011,[3] to map the rest of the planet.[4]

Mercury is similar in appearance to the Moon: it is heavily cratered with regions of smooth plains, has no naturalsatellites and no substantial atmosphere. Unlike the Moon, it has a large iron core, which generates a magnetic fieldabout 1% as strong as that of the Earth.[5] It is an exceptionally dense planet due to the large relative size of its core.Surface temperatures range from about 90 to 700 K (−183 °C to 427 °C),[6] with the subsolar point being the hottestand the bottoms of craters near the poles being the coldest.Recorded observations of Mercury date back to at least the first millennium BC. Before the 4th century BC, Greekastronomers believed the planet to be two separate objects: one visible only at sunrise, which they called Apollo; theother visible only at sunset, which they called Hermes.[7] The English name for the planet comes from the Romans,who named it after the Roman god Mercury, which they equated with the Greek Hermes (Ἑρμῆς). The astronomicalsymbol for Mercury is a stylized version of Hermes' caduceus.[8]

Internal structureMercury is one of four terrestrial planets in the Solar System, and is a rocky body like the Earth. It is the smallestplanet in the Solar System, with an equatorial radius of 2,439.7 km.[3] Mercury is even smaller—albeit moremassive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists ofapproximately 70% metallic and 30% silicate material.[9] Mercury's density is the second highest in the Solar Systemat 5.427 g/cm3, only slightly less than Earth’s density of 5.515 g/cm3.[3] If the effect of gravitational compressionwere to be factored out, the materials of which Mercury is made would be denser, with an uncompressed density of5.3 g/cm3 versus Earth’s 4.4 g/cm3.[10]

Mercury’s density can be used to infer details of its inner structure. While the Earth’s high density results appreciablyfrom gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not nearlyas strongly compressed. Therefore, for it to have such a high density, its core must be large and rich in iron.[11]

Mercury (planet) 4

Size comparison of terrestrial planets (left to right): Mercury, Venus, Earth, and Mars

Internal structure of Mercury:1. Crust: 100–300 km thick

2. Mantle: 600 km thick3. Core: 1,800 km radius

Geologists estimate that Mercury’s core occupies about 42% of its volume; for Earth this proportion is 17%. Recentresearch strongly suggests Mercury has a molten core.[12][13] Surrounding the core is a 500–700 km mantleconsisting of silicates.[14][15] Based on data from the Mariner 10 mission and Earth-based observation, Mercury’scrust is believed to be 100–300 km thick.[16] One distinctive feature of Mercury’s surface is the presence ofnumerous narrow ridges, extending up to several hundred kilometers in length. It is believed that these were formedas Mercury’s core and mantle cooled and contracted at a time when the crust had already solidified.[17]

Mercury's core has a higher iron content than that of any other major planet in the Solar System, and several theorieshave been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal-silicateratio similar to common chondrite meteorites, thought to be typical of the Solar System's rocky matter, and a massapproximately 2.25 times its current mass.[18] Early in the Solar System’s history, Mercury may have been struck bya planetesimal of approximately 1/6 that mass and several hundred kilometers across.[18] The impact would havestripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[18] Asimilar process, known as the giant impact hypothesis, has been proposed to explain the formation of Earth’sMoon.[18]

Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized. Theplanet would initially have had twice its present mass, but as the protosun contracted, temperatures near Mercurycould have been between 2,500 and 3,500 K (Celsius equivalents about 273 degrees less), and possibly even as highas 10,000 K.[19] Much of Mercury’s surface rock could have been vaporized at such temperatures, forming anatmosphere of "rock vapor" which could have been carried away by the solar wind.[19]

A third hypothesis proposes that the solar nebula caused drag on the particles from which Mercury was accreting,which meant that lighter particles were lost from the accreting material.[20] Each hypothesis predicts a differentsurface composition, and two upcoming space missions, MESSENGER and BepiColombo, both aim to makeobservations to test them.[21][22]

Mercury (planet) 5

Surface geology

Image from MESSENGER's second Mercuryflyby. Kuiper crater is just below center. Anextensive ray system emanates from Hokusai

crater near the top.

Mercury’s surface is very similar in appearance to that of the Moon,showing extensive mare-like plains and heavy cratering, indicating thatit has been geologically inactive for billions of years. Since ourknowledge of Mercury's geology has been based on the 1975 Marinerflyby and terrestrial observations, it is the least understood of theterrestrial planets.[13] As data from the recent MESSENGER flyby isprocessed this knowledge will increase. For example, an unusual craterwith radiating troughs has been discovered which scientists called "thespider."[23] It later received the name Apollodorus.

Names for features on Mercury come from a variety of sources. Namescoming from people are limited to the deceased. Craters are named forartists, musicians, painters, and authors who have made outstanding orfundamental contributions to their field. Ridges, or dorsa, are namedfor scientists who have contributed to the study of Mercury.Depressions or fossae are named for works of architecture. Montes arenamed for the word "hot" in a variety of languages. Plains or planitiae are named for Mercury in various languages.Escarpments or rupēs are named for ships of scientific expeditions. Valleys or valles are named for radio telescopefacilities.[24]

Albedo features refer to areas of markedly different reflectivity, as seen by telescopic observation. Mercurypossesses Dorsa (also called "wrinkle-ridges"), Moon-like highlands, Montes (mountains), Planitiae, or plains, Rupes(escarpments), and Valles (valleys).[25][26]

Mercury was heavily bombarded by comets and asteroids during and shortly following its formation 4.6 billion yearsago, as well as during a possibly separate subsequent episode called the late heavy bombardment that came to an end3.8 billion years ago.[27] During this period of intense crater formation, the planet received impacts over its entiresurface,[26] facilitated by the lack of any atmosphere to slow impactors down.[28] During this time the planet wasvolcanically active; basins such as the Caloris Basin were filled by magma from within the planet, which producedsmooth plains similar to the maria found on the Moon.[29][30]

Data from the October 2008 flyby of MESSENGER gave researchers a greater appreciation for the jumbled nature ofMercury's surface. Mercury's surface is more heterogeneous than either Mars' or the Moon's, both of which containsignificant stretches of similar geology, such as maria and plateaus.[31]

Impact basins and craters

Mercury’s Caloris Basin is one of the largest impact features in the Solar System

Mercury (planet) 6

The so-called "Weird Terrain" was formed at the point antipodal to the Caloris Basin impact

Craters on Mercury range in diameter from small bowl-shaped cavities to multi-ringed impact basins hundreds ofkilometers across. They appear in all states of degradation, from relatively fresh rayed craters to highly degradedcrater remnants. Mercurian craters differ subtly from lunar craters in that the area blanketed by their ejecta is muchsmaller, a consequence of Mercury's stronger surface gravity.[32]

The largest known crater is Caloris Basin, with a diameter of 1,550 km.[33] The impact that created the Caloris Basinwas so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater.At the antipode of the Caloris Basin is a large region of unusual, hilly terrain known as the "Weird Terrain". Onehypothesis for its origin is that shock waves generated during the Caloris impact traveled around the planet,converging at the basin’s antipode (180 degrees away). The resulting high stresses fractured the surface.[34]

Alternatively, it has been suggested that this terrain formed as a result of the convergence of ejecta at this basin’santipode.[35]

Overall, about 15 impact basins have been identified on the imaged part of Mercury. A notable basin is the 400 kmwide, multi-ring Tolstoj Basin which has an ejecta blanket extending up to 500 km from its rim and a floor that hasbeen filled by smooth plains materials. Beethoven Basin has a similar-sized ejecta blanket and a 625 km diameterrim.[32] Like the Moon, the surface of Mercury has likely incurred the effects of space weathering processes,including Solar wind and micrometeorite impacts.[36]

PlainsThere are two geologically distinct plains regions on Mercury.[32][37] Gently rolling, hilly plains in the regionsbetween craters are Mercury's oldest visible surfaces,[32] predating the heavily cratered terrain. These inter-craterplains appear to have obliterated many earlier craters, and show a general paucity of smaller craters below about30 km in diameter.[37] It is not clear whether they are of volcanic or impact origin.[37] The inter-crater plains aredistributed roughly uniformly over the entire surface of the planet.Smooth plains are widespread flat areas which fill depressions of various sizes and bear a strong resemblance to thelunar maria. Notably, they fill a wide ring surrounding the Caloris Basin. Unlike lunar maria, the smooth plains ofMercury have the same albedo as the older inter-crater plains. Despite a lack of unequivocally volcaniccharacteristics, the localisation and rounded, lobate shape of these plains strongly support volcanic origins.[32] Allthe Mercurian smooth plains formed significantly later than the Caloris basin, as evidenced by appreciably smallercrater densities than on the Caloris ejecta blanket.[32] The floor of the Caloris Basin is filled by a geologicallydistinct flat plain, broken up by ridges and fractures in a roughly polygonal pattern. It is not clear whether they arevolcanic lavas induced by the impact, or a large sheet of impact melt.[32]

One unusual feature of the planet’s surface is the numerous compression folds, or rupes, which crisscross the plains. As the planet’s interior cooled, it may have contracted and its surface began to deform, creating these features. The folds can be seen on top of other features, such as craters and smoother plains, indicating that the folds are more recent.[38] Mercury’s surface is flexed by significant tidal bulges raised by the Sun—the Sun’s tides on Mercury are

Mercury (planet) 7

about 17 times stronger than the Moon’s on Earth.[39]

Surface conditions and "atmosphere" (exosphere)

Radar image of Mercury's north pole

The surface temperature of Mercury ranges from 100 K to 700 K[40]

due to the absence of an atmosphere and a steep temperature gradientbetween the equator and the poles. The subsolar point reaches about700 K during perihelion then drops to 550 K at aphelion.[41] On thedark side of the planet, temperatures average 110 K.[42] The intensityof sunlight on Mercury’s surface ranges between 4.59 and 10.61 timesthe solar constant (1,370 W·m−2).[43]

Although the daylight temperature at the surface of Mercury isgenerally extremely high, observations strongly suggest that ice existson Mercury. The floors of deep craters at the poles are never exposedto direct sunlight, and temperatures there remain below 102 K; farlower than the global average.[44] Water ice strongly reflects radar, andobservations by the 70 m Goldstone telescope and the VLA in the early1990s revealed that there are patches of very high radar reflection nearthe poles.[45] While ice is not the only possible cause of these reflective regions, astronomers believe it is the mostlikely.[46]

The icy regions are believed to contain about 1014–1015 kg of ice,[47] and may be covered by a layer of regolith thatinhibits sublimation.[48] By comparison, the Antarctic ice sheet on Earth has a mass of about 4×1018 kg, and Mars'south polar cap contains about 1016 kg of water.[47] The origin of the ice on Mercury is not yet known, but the twomost likely sources are from outgassing of water from the planet’s interior or deposition by impacts of comets.[47]

Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time; it doeshave a "tenuous surface-bounded exosphere"[49] containing hydrogen, helium, oxygen, sodium, calcium, potassiumand others. This exosphere is not stable—atoms are continuously lost and replenished from a variety of sources.Hydrogen and helium atoms probably come from the solar wind, diffusing into Mercury’s magnetosphere beforelater escaping back into space. Radioactive decay of elements within Mercury’s crust is another source of helium, aswell as sodium and potassium. MESSENGER found high proportions of calcium, helium, hydroxide, magnesium,oxygen, potassium, silicon and sodium. Water vapor is present, released by a combination of processes such as:comets striking its surface, sputtering creating water out of hydrogen from the solar wind and oxygen from rock, andsublimation from reservoirs of water ice in the permanently shadowed polar craters. The detection of high amountsof water-related ions like O+, OH-, and H2O+ was a surprise.[50][51] Because of the quantities of these ions that weredetected in Mercury's space environment, scientists surmise that these molecules were blasted from the surface orexosphere by the solar wind.[52][53]

Sodium, potassium and calcium were discovered in the atmosphere during the 1980–1990s, and are believed toresult primarily from the vaporization of surface rock struck by micrometeorite impacts.[54] In 2008 magnesium wasdiscovered by MESSENGER probe.[55] Studies indicate that, at times, sodium emissions are localized at points thatcorrespond to the planet's magnetic poles. This would indicate an interaction between the magnetosphere and theplanet's surface.[56]

Mercury (planet) 8

Magnetic field and magnetosphere

Graph showing relative strength of Mercury'smagnetic field

Despite its small size and slow 59-day-long rotation, Mercury has asignificant, and apparently global, magnetic field. According tomeasurements taken by Mariner 10, it is about 1.1% as strong as theEarth’s. The magnetic field strength at the Mercurian equator is about300 nT.[57][58] Like that of Earth, Mercury's magnetic field isdipolar.[56] Unlike Earth, Mercury's poles are nearly aligned with theplanet's spin axis.[59] Measurements from both the Mariner 10 andMESSENGER space probes have indicated that the strength and shapeof the magnetic field are stable.[59]

It is likely that this magnetic field is generated by way of a dynamoeffect, in a manner similar to the magnetic field of Earth.[60][61] Thisdynamo effect would result from the circulation of the planet's iron-rich liquid core. Particularly strong tidal effectscaused by the planet's high orbital eccentricity would serve to keep the core in the liquid state necessary for thisdynamo effect.[62]

Mercury’s magnetic field is strong enough to deflect the solar wind around the planet, creating a magnetosphere. Theplanet's magnetosphere, though small enough to fit within the Earth,[56] is strong enough to trap solar wind plasma.This contributes to the space weathering of the planet's surface.[59] Observations taken by the Mariner 10 spacecraftdetected this low energy plasma in the magnetosphere of the planet's nightside. Bursts of energetic particles weredetected in the planet's magnetotail, which indicates a dynamic quality to the planet's magnetosphere.[56]

During its second flyby of the planet on October 6, 2008, MESSENGER discovered that Mercury’s magnetic fieldcan be extremely "leaky." The spacecraft encountered magnetic "tornadoes" – twisted bundles of magnetic fieldsconnecting the planetary magnetic field to interplanetary space – that were up to 800 km wide or a third of the radiusof the planet. These 'tornadoes' form when magnetic fields carried by the solar wind connect to Mercury's magneticfield. As the solar wind blows past Mercury's field, these joined magnetic fields are carried with it and twist up intovortex-like structures. These twisted magnetic flux tubes, technically known as flux transfer events, form openwindows in the planet's magnetic shield through which the solar wind may enter and directly impact Mercury'ssurface.[63]

The process of linking interplanetary and planetary magnetic fields, called magnetic reconnection, is commonthroughout the cosmos. It occurs in Earth's magnetic field, where it generates magnetic tornadoes as well. TheMESSENGER observations show the reconnection rate is ten times higher at Mercury. Mercury's proximity to theSun only accounts for about a third of the reconnection rate observed by MESSENGER.[63]

Orbit and rotation

Mercury (planet) 9

Orbit of Mercury (yellow). Dates refer to 2006.

Animation of Mercury's and Earth's revolution around the Sun

Mercury has the most eccentric orbit of all the planets; its eccentricity is 0.21 with its distance from the Sun rangingfrom 46 to 70 million kilometers. It takes 88 days to complete an orbit. The diagram on the right illustrates theeffects of the eccentricity, showing Mercury's orbit overlaid with a circular orbit having the same semi-major axis.The higher velocity of the planet when it is near perihelion is clear from the greater distance it covers in each 5-dayinterval. The size of the spheres, inversely proportional to their distance from the Sun, is used to illustrate thevarying heliocentric distance. This varying distance to the Sun, combined with a 3:2 spin-orbit resonance of theplanet's rotation around its axis, result in complex variations of the surface temperature.[9] This resonance makes asingle day on Mercury last exactly two Mercury years, or about 176 Earth days.[64]

Mercury's orbit is inclined by 7 degrees to the plane of Earth's orbit (the ecliptic), as shown in the diagram on theright. As a result, transits of Mercury across the face of the Sun can only occur when the planet is crossing the planeof the ecliptic at the time it lies between the Earth and the Sun. This occurs about every seven years on average.[65]

Mercury's axial tilt is almost zero,[66] with the best measured value as low as 0.027 degrees.[7] This is significantlysmaller than that of Jupiter, which has the second smallest axial tilt of all planets at 3.1 degrees. This means that toan observer at Mercury's poles, the center of the Sun never rises more than 2.1 arcminutes above the horizon.[7]

At certain points on Mercury's surface, an observer would be able to see the Sun rise about halfway, then reverse andset before rising again, all within the same Mercurian day. This is because approximately four days beforeperihelion, Mercury's angular orbital velocity exactly equals its angular rotational velocity so that the Sun's apparentmotion ceases; at perihelion, Mercury's angular orbital velocity then exceeds the angular rotational velocity. Thus,the Sun appears to move in a retrograde direction. Four days after perihelion, the Sun’s normal apparent motionresumes at these points.[9]

Mercury (planet) 10

Spin–orbit resonance

After one orbit, Mercury has rotated 1.5 times, soafter two complete orbits the same hemisphere is

again illuminated.

For many years it was thought that Mercury was synchronously tidallylocked with the Sun, rotating once for each orbit and always keepingthe same face directed towards the Sun, in the same way that the sameside of the Moon always faces the Earth. Radar observations in 1965proved that the planet has a 3:2 spin–orbit resonance, rotating threetimes for every two revolutions around the Sun; the eccentricity ofMercury’s orbit makes this resonance stable—at perihelion, when thesolar tide is strongest, the Sun is nearly still in Mercury’s sky.[67]

The original reason astronomers thought it was synchronously lockedwas that, whenever Mercury was best placed for observation, it wasalways nearly at the same point in its 3:2 resonance, hence showing thesame face. This is because, coincidentally, Mercury's rotation period isalmost exactly half of its synodic period with respect to Earth. Due toMercury's 3:2 spin–orbit resonance, a solar day (the length betweentwo meridian transits of the Sun) lasts about 176 Earth days.[9] Asidereal day (the period of rotation) lasts about 58.7 Earth days.[9]

Simulations indicate that the orbital eccentricity of Mercury varies chaotically from nearly zero (circular) to morethan 0.45 over millions of years due to perturbations from the other planets.[9][68] This is thought to explainMercury's 3:2 spin-orbit resonance (rather than the more usual 1:1), since this state is more likely to arise during aperiod of high eccentricity.[69] Numerical simulations show that a resonant orbital interaction with Jupiter may causethe eccentricity of Mercury's orbit to increase to the point where there is a 1% chance that the planet may collidewith Venus within the next five billion years.[70]

Advance of perihelionIn 1859, the French mathematician and astronomer Urbain Le Verrier reported that the slow precession of Mercury’sorbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the knownplanets. He suggested, among possible explanations, that another planet (or perhaps instead a series of smaller'corpuscules') might exist in an orbit even closer to the Sun than that of Mercury, to account for this perturbation.[71]

(Other explanations considered included a slight oblateness of the Sun.) The success of the search for Neptune basedon its perturbations of the orbit of Uranus led astronomers to place faith in this possible explanation, and thehypothetical planet was named Vulcan, but no such planet was ever found.[72]

The perihelion precession of Mercury is 5600 arc seconds (1.5556°) per century. Newtonian mechanics, taking intoaccount all the effects from the other planets, predicts a precession of 5557 seconds of arc (1.5436°) per century.[73]

In the early 20th century, Albert Einstein’s General Theory of Relativity provided the explanation for the observedprecession. The effect is very small: the Mercurian relativistic perihelion advance excess is just 42.98 arcseconds percentury, therefore it requires a little over twelve million orbits for a full excess turn. Similar, but much smaller,effects operate for other planets: 8.62 arcseconds per century for Venus, 3.84 for Earth, 1.35 for Mars, and 10.05 for1566 Icarus.[74][75]

Mercury (planet) 11

Coordinate systemLongitude on Mercury increases in the westerly direction. A small crater named Hun Kal provides the referencepoint for measuring longitude. The center of Hun Kal is 20° west longitude.[76]

Observation

First high-resolution image of Mercurytransmitted by MESSENGER (false color)

Mercury’s apparent magnitude varies between −2.6[10] (brighter thanthe brightest star Sirius) and about +5.7. The extremes occur whenMercury is close to the Sun in the sky.[10][11] Observation of Mercuryis complicated by its proximity to the Sun, as it is lost in the Sun’sglare for much of the time. Mercury can be observed for only a briefperiod during either morning or evening twilight. The Hubble SpaceTelescope cannot observe Mercury at all, due to safety procedureswhich prevent its pointing too close to the Sun.[77]

Like the Moon, Mercury exhibits phases as seen from Earth. It is"new" at inferior conjunction and "full" at superior conjunction. Theplanet is rendered invisible from Earth on both of these occasionsbecause of its relative nearness to the Sun. The first and last quarterphases occur at greatest elongation east and west, respectively, whenMercury's separation from the Sun ranges anywhere from 17.9° atperihelion to 27.8° at aphelion.[78][79] At greatest elongation west, Mercury rises at its earliest before the Sun, and atgreatest elongation east, it sets at its latest after the Sun.[80]

Mercury attains inferior conjunction every 116 days on average,[3] but this interval can range from 105 days to 129days due to the planet’s eccentric orbit. Mercury can come as close as 77.3 million km to the Earth.[3] In 871 AD, thenearest approach was the first in about 41,000 years to be closer than 82.2 Gm, something that has happened 68times since then. After much longer gaps, the next approach to within 82.1 Gm is in 2679, and to 82 Gm in 4487.But it will not be closer to Earth than 80 Gm until 28,622.[81] Its period of retrograde motion as seen from Earth canvary from 8 to 15 days on either side of inferior conjunction. This large range arises from the planet's high orbitaleccentricity.[9]

Mercury is more often easily visible from Earth’s Southern Hemisphere than from its Northern Hemisphere; this isbecause its maximum possible elongations west of the Sun always occur when it is early autumn in the SouthernHemisphere, while its maximum possible eastern elongations happen during late winter in the SouthernHemisphere.[80] In both of these cases, the angle Mercury strikes with the ecliptic is maximized, allowing it to riseseveral hours before the Sun in the former instance and not set until several hours after sundown in the latter incountries located at southern temperate zone latitudes, such as Argentina and New Zealand.[80] By contrast, atnorthern temperate latitudes, Mercury is never above the horizon of a more-or-less fully dark night sky. Mercurycan, like several other planets and the brightest stars, be seen during a total solar eclipse.[82]

Mercury is brightest as seen from Earth when it is at a full phase. Although the planet is farthest away from Earthwhen it is full the greater illuminated area that is visible and the opposition brightness surge more than compensatesfor the distance.[10] The opposite is true for Venus, which appears brightest when it is a crescent, because it is muchcloser to Earth than when gibbous.[10][83]

Mercury (planet) 12

Studies

Ancient astronomersThe earliest known recorded observations of Mercury are from the Mul.Apin tablets. These observations were mostlikely made by an Assyrian astronomer around the 14th century BC.[84] The cuneiform name used to designateMercury on the Mul.Apin tablets is transcribed as Udu.Idim.Gu\u4.Ud ("the jumping planet").[85][86] Babylonianrecords of Mercury date back to the 1st millennium BC. The Babylonians called the planet Nabu after the messengerto the gods in their mythology.[87]

The ancient Greeks of Hesiod's time knew the planet as Στίλβων (Stilbon), meaning "the gleaming", and Ἑρμάων(Hermaon).[88] Later Greeks called the planet Apollo when it was visible in the morning sky, and Hermes whenvisible in the evening. Around the 4th century BC, Greek astronomers came to understand that the two namesreferred to the same body. The Romans named the planet after the swift-footed Roman messenger god, Mercury(Latin Mercurius), which they equated with the Greek Hermes, because it moves across the sky faster than any otherplanet.[7][89] The Roman-Egyptian astronomer Ptolemy wrote about the possibility of planetary transits across theface of the Sun in his work Planetary Hypotheses. He suggested that no transits had been observed either becauseplanets such as Mercury were too small to see, or because the transits were too infrequent.[90]

Ibn al-Shatir's model for the appearances ofMercury, showing the multiplication of epicycles

using the Tusi-couple, thus eliminating thePtolemaic eccentrics and equant.

In ancient China, Mercury was known as Chen Xing (辰 星), the HourStar. It was associated with the direction north and the phase of waterin the Wu Xing.[91] Modern Chinese, Korean, Japanese andVietnamese cultures refer to the planet literally as the “water star” (水星), based on the Five elements.[92] Hindu mythology used the nameBudha for Mercury, and this god was thought to preside overWednesday.[93] The god Odin (or Woden) of Germanic paganism wasassociated with the planet Mercury and Wednesday.[94] The Maya mayhave represented Mercury as an owl (or possibly four owls; two for themorning aspect and two for the evening) that served as a messenger tothe underworld.[95]

In ancient Indian astronomy, the Surya Siddhanta, an Indianastronomical text of the 5th century, estimates the diameter of Mercuryas 3,008 miles, an error of less than 1% from the currently accepteddiameter of 3032 miles (unknown operator: u'strong' km). Thisestimate was based upon an inaccurate guess of the planet's angulardiameter as 3.0 arcminutes.

In medieval Islamic astronomy, the Andalusian astronomer Abū IshāqIbrāhīm al-Zarqālī in the 11th century described the deferent of

Mercury's geocentric orbit as being oval, like an egg or a pignon, although this insight did not influence hisastronomical theory or his astronomical calculations.[96][97] In the 12th century, Ibn Bajjah observed "two planets asblack spots on the face of the Sun," which was later suggested as the transit of Mercury and/or Venus by theMaragha astronomer Qotb al-Din Shirazi in the 13th century.[98] (Note that most such medieval reports of transitswere later taken as observations of sunspots.[99])

In India, the Kerala school astronomer Nilakantha Somayaji in the 15th century developed a partially heliocentricplanetary model in which Mercury orbits the Sun, which in turn orbits the Earth, similar to the Tychonic system laterproposed by Tycho Brahe in the late 16th century.[100]

Mercury (planet) 13

Ground-based telescopic research

Transit of Mercury. Mercury is the small dot inthe lower center, in front of the Sun. The darkarea on the left of the solar disk is a sunspot.

The first telescopic observations of Mercury were made by Galileo inthe early 17th century. Although he observed phases when he looked atVenus, his telescope was not powerful enough to see the phases ofMercury. In 1631 Pierre Gassendi made the first telescopicobservations of the transit of a planet across the Sun when he saw atransit of Mercury predicted by Johannes Kepler. In 1639 GiovanniZupi used a telescope to discover that the planet had orbital phasessimilar to Venus and the Moon. The observation demonstratedconclusively that Mercury orbited around the Sun.[9]

A very rare event in astronomy is the passage of one planet in front ofanother (occultation), as seen from Earth. Mercury and Venus occulteach other every few centuries, and the event of May 28, 1737 is theonly one historically observed, having been seen by John Bevis at theRoyal Greenwich Observatory.[101] The next occultation of Mercury byVenus will be on December 3, 2133.[102]

The difficulties inherent in observing Mercury mean that it has been far less studied than the other planets. In 1800Johann Schröter made observations of surface features, claiming to have observed 20 km high mountains. FriedrichBessel used Schröter's drawings to erroneously estimate the rotation period as 24 hours and an axial tilt of 70°.[103]

In the 1880s Giovanni Schiaparelli mapped the planet more accurately, and suggested that Mercury’s rotationalperiod was 88 days, the same as its orbital period due to tidal locking.[104] This phenomenon is known assynchronous rotation and is shown by Earth’s Moon. The effort to map the surface of Mercury was continued byEugenios Antoniadi, who published a book in 1934 that included both maps and his own observations.[56] Many ofthe planet's surface features, particularly the albedo features, take their names from Antoniadi's map.[105]

In June 1962 Soviet scientists at the Institute of Radio-engineering and Electronics of the USSR Academy ofSciences led by Vladimir Kotelnikov became first to bounce radar signal off Mercury and receive it, starting radarobservations of the planet.[106][107][108] Three years later radar observations by Americans Gordon Pettengill and R.Dyce using 300-meter Arecibo Observatory radio telescope in Puerto Rico showed conclusively that the planet’srotational period was about 59 days.[109][110] The theory that Mercury's rotation was synchronous had becomewidely held, and it was a surprise to astronomers when these radio observations were announced. If Mercury weretidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was muchhotter than expected. Astronomers were reluctant to drop the synchronous rotation theory and proposed alternativemechanisms such as powerful heat-distributing winds to explain the observations.[111]

Italian astronomer Giuseppe Colombo noted that the rotation value was about two-thirds of Mercury's orbital period,and proposed that the planet's orbital and rotational periods were locked into a 3:2 rather than a 1:1 resonance.[112]

Data from Mariner 10 subsequently confirmed this view.[113] This means that Schiaparelli's and Antoniadi's mapswere not "wrong". Instead, the astronomers saw the same features during every second orbit and recorded them, butdisregarded those seen in the meantime, when Mercury's other face was toward the Sun, since the orbital geometrymeant that these observations were made under poor viewing conditions.[103]

Ground-based optical observations did not shed much further light on the innermost planet, but radio astronomers using interferometery at microwave wavelengths, a technique that enables removal of the solar radiation, were able to discern physical and chemical characteristics of the subsurface layers to a depth of several meters.[114][115] Not until the first space probe flew past Mercury did many of its most fundamental morphological properties become known. Moreover, recent technological advances have led to improved ground-based observations. In 2000, high-resolution lucky imaging observations were conducted by the Mount Wilson Observatory 1.5 meter Hale

Mercury (planet) 14

telescope. They provided the first views that resolved surface features on the parts of Mercury which were notimaged in the Mariner mission.[116] Later imaging has shown evidence of a huge double-ringed impact basin evenlarger than the Caloris Basin in the non-Mariner-imaged hemisphere. It has informally been dubbed the SkinakasBasin.[117] Most of the planet has been mapped by the Arecibo radar telescope, with 5 km resolution, including polardeposits in shadowed craters of what may be water ice.[118]

Research with space probesReaching Mercury from Earth poses significant technical challenges, since the planet orbits so much closer to theSun than does the Earth. A Mercury-bound spacecraft launched from Earth must travel over 91 million kilometersinto the Sun’s gravitational potential well. Mercury has an orbital speed of 48 km/s, while Earth's orbital speed is30 km/s. Thus the spacecraft must make a large change in velocity (delta-v) to enter a Hohmann transfer orbit thatpasses near Mercury, as compared to the delta-v required for other planetary missions.[119]

The potential energy liberated by moving down the Sun’s potential well becomes kinetic energy; requiring anotherlarge delta-v change to do anything other than rapidly pass by Mercury. To land safely or enter a stable orbit thespacecraft would rely entirely on rocket motors. Aerobraking is ruled out because the planet has very littleatmosphere. A trip to Mercury requires more rocket fuel than that required to escape the Solar System completely.As a result, only two space probes have visited the planet so far.[120] A proposed alternative approach would use asolar sail to attain a Mercury-synchronous orbit around the Sun.[121]

Mariner 10

The Mariner 10 probe, the first probe to visit the innermost planet

View of Mercury from Mariner 10

The first spacecraft to visit Mercury was NASA’s Mariner 10 (1974–75).[7] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury, making it both the first spacecraft to use this gravitational “slingshot” effect and the first NASA mission to visit multiple planets.[119] Mariner 10 provided the first close-up images of Mercury’s surface, which immediately showed its heavily cratered nature, and revealed many other types of geological features, such as the giant scarps which were later ascribed to the effect of the planet shrinking slightly as its iron core cools.[122] Unfortunately, due to the length of Mariner 10's orbital period, the same face of the planet was lit at each of Mariner 10’s close approaches. This made observation of both sides of the planet

Mercury (planet) 15

impossible,[123] and resulted in the mapping of less than 45% of the planet’s surface.[124]

On March 27, 1974, two days before its first flyby of Mercury, Mariner 10's instruments began registering largeamounts of unexpected ultraviolet radiation near Mercury. This led to the tentative identification of Mercury's moon.Shortly afterward, the source of the excess UV was identified as the star 31 Crateris, and Mercury's moon passed intoastronomy's history books as a footnote.The spacecraft made three close approaches to Mercury, the closest of which took it to within 327 km of thesurface.[125] At the first close approach, instruments detected a magnetic field, to the great surprise of planetarygeologists—Mercury’s rotation was expected to be much too slow to generate a significant dynamo effect. Thesecond close approach was primarily used for imaging, but at the third approach, extensive magnetic data wereobtained. The data revealed that the planet’s magnetic field is much like the Earth’s, which deflects the solar windaround the planet. The origin of Mercury’s magnetic field is still the subject of several competing theories.[126]

On March 24, 1975, just eight days after its final close approach, Mariner 10 ran out of fuel. Since its orbit could nolonger be accurately controlled, mission controllers instructed the probe to shut down.[127] Mariner 10 is thought tobe still orbiting the Sun, passing close to Mercury every few months.[128]

MESSENGER

MESSENGER being prepared for launch

A second NASA mission to Mercury, named MESSENGER (MErcurySurface, Space ENvironment, GEochemistry, and Ranging), waslaunched on August 3, 2004, from the Cape Canaveral Air ForceStation aboard a Boeing Delta 2 rocket. It made a fly-by of the Earth inAugust 2005, and of Venus in October 2006 and June 2007 to place itonto the correct trajectory to reach an orbit around Mercury.[129] A firstfly-by of Mercury occurred on January 14, 2008, a second on October6, 2008,[130] and a third on September 29, 2009.[131] Most of thehemisphere not imaged by Mariner 10 has been mapped during thesefly-bys. The probe successfully entered an elliptical orbit around theplanet on March 18, 2011. The first orbital image of Mercury was obtained on March 29, 2011. The nominalmapping mission is one terrestrial year.[130]

The mission is designed to clear up six key issues: Mercury’s high density, its geological history, the nature of itsmagnetic field, the structure of its core, whether it has ice at its poles, and where its tenuous atmosphere comes from.To this end, the probe is carrying imaging devices which will gather much higher resolution images of much more ofthe planet than Mariner 10, assorted spectrometers to determine abundances of elements in the crust, andmagnetometers and devices to measure velocities of charged particles. Detailed measurements of tiny changes in theprobe’s velocity as it orbits will be used to infer details of the planet’s interior structure.[21]

BepiColombo

The European Space Agency is planning a joint mission with Japan called BepiColombo, which will orbit Mercurywith two probes: one to map the planet and the other to study its magnetosphere.[132] Once launched, the spacecraftbus is expected to reach Mercury in 2019.[133] The bus will release a magnetometer probe into an elliptical orbit,then chemical rockets will fire to deposit the mapper probe into a circular orbit. Both probes will operate for aterrestrial year.[132] The mapper probe will carry an array of spectrometers similar to those on MESSENGER, andwill study the planet at many different wavelengths including infrared, ultraviolet, X-ray and gamma ray.[134]

Mercury (planet) 16

In culture

Mercury, from a 1550 edition of Guido Bonatti'sLiber astronomiae.

In Western astrology, Mercury is the ruling planet of Gemini andVirgo. That is, the supposed astrological influence of the planet wasgreatest when it was observed in these constellations.[135]

On maps of Mercury created by astronomers before the detailedmapping of recent decades, the Solitudo Hermae Trismegisti(Wilderness of Hermes Trismegistus) was identified as a major featureof the planet Mercury, covering about one-fourth of the planet in theSE quadrant.[136]

Mercury, the Winged Messenger, is a movement in Gustav Holst's ThePlanets.

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[105] Merton E. Davies, et al. (1978). "Surface Mapping" (http:/ / history. nasa. gov/ SP-423/ surface. htm). Atlas of Mercury (http:/ / history.nasa. gov/ SP-423/ sp423. htm). NASA Office of Space Sciences. . Retrieved 2008-05-28.

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[110] Mercury (http:/ / scienceworld. wolfram. com/ astronomy/ Mercury. html) at Eric Weisstein's 'World of Astronomy'[111] Murray, Bruce C.; Burgess, Eric (1977). Flight to Mercury. Columbia University Press. ISBN 0-231-03996-4.[112] Colombo, G. (1965). "Rotational Period of the Planet Mercury". Nature 208 (5010): 575. Bibcode 1965Natur.208..575C.

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References

External links• Atlas of Mercury—NASA (http:/ / history. nasa. gov/ SP-423/ sp423. htm)• Gazeteer of Planetary Nomenclature – Mercury (USGS) (http:/ / planetarynames. wr. usgs. gov/ jsp/

SystemSearch2. jsp?System=Mercury)• SolarViews.com—Mercury (http:/ / www. solarviews. com/ eng/ mercury. htm)• Astronomy Cast: Mercury (http:/ / www. astronomycast. com/ astronomy/ episode-49-mercury/ )• Geody Mercury (http:/ / www. geody. com/ ?world=mercury) World’s search engine that supports NASA World

Wind, Celestia, and other applications.• A Day On Mercury (http:/ / btc. montana. edu/ MESSENGER/ Interactives/ ANIMATIONS/ Day_On_Mercury/

day_on_mercury_full. htm) flash animation• Mercury articles in Planetary Science Research Discoveries (http:/ / www. psrd. hawaii. edu/ Archive/

Archive-Mercury. html)• ‘BepiColombo’, ESA’s Mercury Mission (http:/ / www. esa. int/ export/ esaSC/ 120391_index_0_m. html)• ‘Messenger’, NASA’s Mercury Mission (http:/ / messenger. jhuapl. edu/ )

Article Sources and Contributors 22

Article Sources and ContributorsMercury (planet)  Source: http://en.wikipedia.org/w/index.php?oldid=477595969  Contributors: -- April, 0, 007croc, 0nullbinary0, 129.128.188.xxx, 1297, 808, 84user, A bit iffy, A. Parrot, A.di M., ALLFUCKYOU, Aahh, Acalamari, Aces lead, Acs4b, Adam McMaster, Adashiel, Addshore, Adi, Adraeus, Ageekgal, Agentgonzo, Ahoerstemeier, Aitias, Ajcounter, Ajraddatz,Akhristov, Aksi great, Alansohn, Albireo3000, Aldebaran66, Aledubr, Alex.muller, AlexDenney, AlexiusHoratius, Alfio, [email protected], Alison, Alksub, All Is One, Allchopin, Allstarecho,Altenmann, Amakuru, Amillar, Aminullah, Anaxial, Andattaca2010, Andonic, Andy120290, Angela, Angela26, Angie Y., Angr, Anirban89, Anishkicks, AnnaFrance, Anonymous editor,Antandrus, Antony1103, Anville, Arakunem, Archaeopteryx, Archer3, Arctic.gnome, Arjun01, Army1987, ArnoldReinhold, Arthur Fonzarelli, Arwel Parry, Ascidian, Ashmoo, Aster2,AstroNomer, Astrobhadauria, Athenean, AuburnPilot, Auricfuzz, Av0id3r, Avenue, AvicAWB, Avicennasis, Avoided, Awolf002, Axl, Ayudante, Az1568, B.d.mills, BFDSB, BGManofID,Badanedwa, Badmadrain, Banes, BarroColorado, BartBenjamin, Barvinok, Basilicofresco, Bassem18, Bawolff, Bcorr, Begoon, Beland, Bender235, Beno1000, Benwildeboer, Bergsten, Bibila,Bigdan201, BiggKwell, BillCook, Biranavy, Bkell, Bkmays, Blindman shady, Blobinator11, BlueMoonlet, Bluezy, BlytheG, Bobblewik, Bobo192, Bobrulesu, Bobthemonkeyz, BodachMor,Bogdangiusca, Bojangles04, Bornhj, Bpell, Brain, Branddobbe, Brandon998, Brian0918, BrianHansen, BrianY, Brighterorange, Brion VIBBER, Bryan Derksen, Bubba73, Burndownthedisco,CSWarren, CWii, Cacadril, Cactus.man, Cadwaladr, Caesar Rodney, Caesura, Cafzal, Caknuck, Calabraxthis, Caltas, Caltrop, Cam, Camw, Can't sleep, clown will eat me, CanadianCaesar,Candee puffs, Canderson7, Canyon1980, Captainbeefart, Carapar999, Catswilltakeovertheworld1day, CelticJobber, Cenarium, CenozoicEra, Ceranthor, Chadjj, Chal7ds, CharlesC, Chesnok,Chetanbhawani, ChicXulub, Chitomcgee, Chrisjj, Chuq, Cimon Avaro, Circeus, Ciroa, Ckatz, Clarityfiend, Claudio M Souza, Cmapm, Cocu, Codwiki, Colipon, ComaDivine, CommonsDelinker,Complex (de), Conversion script, Cookiedog, Corpx, CosineKitty, Cpcheung, Craigsjones, Crakkpot, Crazycomputers, CryptoDerk, Curps, Cybercobra, Cyclopaedia, Cyclopia, Cyde, Cyktsui,CzarNick, D, D.M. from Ukraine, D4g0thur, D4tinf4mznigg4, D6, DVD R W, Dalit Llama, Dan D. Ric, Dan East, Dan100, Danarmstrong, DancingPenguin, Daniel bg, Daniel5127, Danny,Danski14, DasallmächtigeJ, Daveros2008, Davewild, Davidhorman, Dawnseeker2000, Dbach, DeadEyeArrow, Deeptrivia, Deflective, Dekaels, Dekimasu, Delldot, Deltabeignet, Deor,DerHexer, Deuar, Deus Ex, Devatipan, Dfoofnik, Dhartung, Dhiresh, Dialashop, Diannaa, Diderot, Didsrocks, Digitalme, Dingly, Discospinster, Dismas, Divad89, Djinn112, Dlohcierekim,Dlohcierekim's sock, Dolda2000, Don Alessandro, Donarreiskoffer, Doradus, Doze, Dozols, Dp462090, Dr pda, Dr. Submillimeter, DrKiernan, Dracontes, DragonflySixtyseven, Drlesmgolden,Drmies, Dstlascaux, Dtgriscom, Dureo, Dwaipayanc, Dysepsion, E. Ripley, ESkog, Easel3, EasyTarget, Ed Poor, Ed g2s, Edivorce, Edsanville, Egil, Eiaschool, El C, El Shaday, Elader, Elassint,Eleven even, Elijya, Eltener, Eluchil404, Emerson7, Enceladusgeysers, EncycloPetey, Enlil Ninlil, Enviroboy, Eob, Erdal Ronahi, Erimus, Escape Orbit, EscapingLife, Eteq, Euicho,Eurocommuter, Everyking, Evil Monkey, F1enter, Fact man 13, FakeAvJs-A, Falsifian, Fanyavizuri, Faz90, Fearophobia, Felix Dance, Femto, FileMaster, FlatheadScrewdriver, Fleela,Fluffernutter, Flyguy649, Fonzy, Fordmadoxfraud, Fram, Frecklefoot, Freyr, Fryed-peach, Fsswsb, Gadfium, Gcapp1959, Gdr, Gekedo, Gene Nygaard, Geneb1955, General Eisenhower, Geni,Geoffrey.landis, George Lin123, Geruhjima, Gholam, Giftlite, Gilliam, Ginger bowl, Glane23, Glen, Gman124, Gmaxwell, Godlord2, Gogo Dodo, GoingBatty, GoodDay, Goon Noot,Gracenotes, GraemeL, Graham87, GravityIsForSuckers, Graywords, Green meklar, GregAsche, GregorB, Grzond, Gublefink, Gurch, Gwillhickers, Gzkn, HJ Mitchell, Hadal, Haikon, HairyDude, HalfShadow, HannahCRichards, HarDNox, Hardee67, Hassocks5489, Haukurth, Haza-w, Hdt83, Head, Headbomb, Heimstern, Heliac, Henry Flower, HenryLi, Heron, Hfastedge,Hibernian, Hike395, Hmrox, Hong Qi Gong, HorsePunchKid, Hurricane Devon, Huw Powell, Hydrargyrum, ICroch, IVAN3MAN, Iago Dali, Ian Pitchford, Iapetus, Icairns, Icey, IdLoveOne,Igodard, Igorwindsor, Ihcoyc, Ikanreed, Ike9898, Ilikefood, Ilikerps, Illuminatedwax, Iluvcapra, In fact, Indon, Indy-MD, IntrplnetSarah, Iosef, Iridescent, Ixfd64, J Di, J.delanoy, JForget,JFreeman, JHunterJ, Jaeson, Jagged 85, Jameswheeleratskool, Jay Litman, Jayen466, Jbhuntly, Jeff Relf, JeffK1971, Jensbn, Jeppesn, JeramieHicks, Jerichi, Jeronimo, Jerry1234567898765,Jespinos, Jess Mars, Jfdwolff, Jh51681, JiFish, Jim77742, Jimp, Jiy, Jkl, Jklin, Jmorgan, Joanjoc, JoanneB, Joao, Joe Kress, Joedeshon, Joelholdsworth, Joemanhy6, John, John of Reading,John254, JohnOwens, JohnSawyer, Jojit fb, Jonathan Grynspan, JorisvS, Jorunn, Jose77, Jossi, 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Image Sources, Licenses and ContributorsFile:Mercury in color - Prockter07 centered.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_in_color_-_Prockter07_centered.jpg  License: Public Domain  Contributors:NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. Edited version of Image:Mercury in color - Prockter07.jpg by Papa Lima Whiskey.Image:Speakerlink.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Speakerlink.svg  License: Creative Commons Attribution 3.0  Contributors: Woodstone. Original uploader wasWoodstone at en.wikipediaImage:Terrestrial planet size comparisons.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Terrestrial_planet_size_comparisons.jpg  License: Public Domain  Contributors:wikipedia user Brian0918Image:Mercury Internal Structure.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_Internal_Structure.svg  License: GNU Free Documentation License  Contributors: JoelHoldsworth ()File:CW0131775256F Kuiper Crater.png  Source: http://en.wikipedia.org/w/index.php?title=File:CW0131775256F_Kuiper_Crater.png  License: Public Domain  Contributors: NASA / JohnsHopkins University Applied Physics Laboratory / Carnegie Institution of WashingtonImage:Caloris basin labeled.png  Source: http://en.wikipedia.org/w/index.php?title=File:Caloris_basin_labeled.png  License: Public Domain  Contributors: NASAImage:Mercury weird terrain.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_weird_terrain.jpg  License: Public Domain  Contributors: Original uploader was Deuar aten.wikipedia

Image Sources, Licenses and Contributors 23

File:Merc fig2sm.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Merc_fig2sm.jpg  License: Public Domain  Contributors: Quote from : "NASA photo by..."File:Mercury Magnetic Field NASA.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_Magnetic_Field_NASA.jpg  License: Public Domain  Contributors: Joancreus,Materialscientist, Ruslik0Image:ThePlanets Orbits Mercury PolarView.svg  Source: http://en.wikipedia.org/w/index.php?title=File:ThePlanets_Orbits_Mercury_PolarView.svg  License: Creative CommonsAttribution-ShareAlike 3.0 Unported  Contributors: User:EurocommuterImage:Mercuryorbitsolarsystem.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Mercuryorbitsolarsystem.gif  License: Creative Commons Attribution-Sharealike 3.0  Contributors:User:LookangFile:Mercury's orbital resonance.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury's_orbital_resonance.svg  License: GNU Free Documentation License  Contributors: Tos,converted to SVG from PNG. Original author: WorldtravellerFile:Mercury in color c1000 700 430.png  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_in_color_c1000_700_430.png  License: Public Domain  Contributors: NASA/JohnsHopkins University Applied Physics Laboratory/Carnegie Institution of WashingtonImage:Shatir500.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Shatir500.jpg  License: Public Domain  Contributors: Azdi80, Konstable, Leinad-Z, 1 anonymous editsFile:Mercury transit 1.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_transit_1.jpg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors: MilaZinkovaImage:Mariner 10.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mariner_10.jpg  License: Public Domain  Contributors: Oder Zeichner: unbekannt Original uploader was W.wolnyat de.wikipediaImage:Mercury Mariner10.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury_Mariner10.jpg  License: GNU Free Documentation License  Contributors: Original uploaderwas Ricnun at en.wikipediaFile:MESSENGER Assembly.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:MESSENGER_Assembly.jpg  License: Public Domain  Contributors: NASAFile:Mercury-bonatti.png  Source: http://en.wikipedia.org/w/index.php?title=File:Mercury-bonatti.png  License: Public Domain  Contributors: Smerdis of Tlön

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