Charon (Charon/ˈ ʃʃ n/or/ˈ k ɛ ə r ə n/, often translated as Caron, also known as (134340) Pluto I,) Yesdwarf planetThe largest of the five known natural moons of Pluto.Its average radius is 606 kilometers (377 miles).The underworld guard is the successorPluto（Pluto），Eris （Eris），Haumea （Haumea），Bird God Star(Makemake) andGonggong Star(Gonggong), the sixth largest offshore Uranus object.[1]On June 22, 1978, the American astronomer James ChristyU.S.AWashington, D.CUS Naval ObservatoryThe discovery of Triton was made using photographic negatives taken with the telescope at the Flagstaff Station (NOFS) of the US Naval Observatory.
The diameter of Pluto is half that of Pluto, and its mass is one eighth that of Pluto. Compared with its parent planet, Pluto is a very large satellite.Its gravitational influence makes Pluto's systemcentroidLocated outside Pluto.The red and brown cap on the north pole of Hades One is composed ofTorin(Tholins) organic macromolecules, which may be essential to life.These tolins are released from Pluto's atmospheremethane，nitrogenAnd related gases and transferred to the surface of the satellite 19000km (12000 miles) away.[2]
Detector onlyNew Horizon NoThe spacecraft has visited the Pluto system.It approached Triton in 2015, with the nearest distance of 27000 km (17000 miles).
James Christy, an astronomer from the US Naval Observatory, discovered Pluto using the 1.55 meter (61 inch) telescope of the US Naval Observatory's Flagstaff Station (NOFS).[5]On June 22, 1978, on the photographic plate taken with a telescope two months ago, Christie noticed that Pluto's high magnification image periodically appeared a slight bulge, which can be traced back to the picture on April 29, 1965.[6]International Astronomical UnionOn July 7, 1978, Christie's discovery was officially announced to the world.[7]
It is found that Pluto's circular surface has periodic slight bulges in the picture of Pluto
Subsequent observations of Pluto confirmed that the bulge was caused by a smaller companion star.From Pluto'sPhotorefractive curveIt is known that the periodicity of the bulge is similar to that of PlutoRotation periodMatch.This indicates that Pluto has a synchronous orbit satellite, which strongly indicates that the bulge effect is real rather than false.Therefore, Pluto's size, mass and other physical characteristics need to be reassessed, because the previously calculated Pluto's mass and albedo are actually the Pluto Pluto 1 system.
When Pluto and Pluto entered the five-year period from 1985 to 1990OccultationAnd transit, scientists eliminated the existence of its doubt.Seen from Earth, the orbital plane of Pluto Pluto and Plutocelestial sphereThis happens when the plane is vertical, and only twice in the 248 year cycle of Pluto's orbit.Fortunately, one of these intervals happened just after Pluto I was discovered.
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writerEdmund Hamilton(Edmond Hamilton)（Calling Captain Future）The three moons of Pluto are named Charon, Styx and Cerberus respectively.Today, Charon is the first sign of Pluto, Styx is the fifth sign of Pluto, and Kerberos is the fourth sign of Pluto (in Greek, Cerberus has been used for the 1865 asteroid).[8]According to the established practice at that time, the temporary name S/1978 P 1 was initially used after the discovery of Hades One.On June 24, 1978, Christy first proposed to use the name Charon as the scientific pronunciation version of his wife Charlene's nickname "Char".[9][10]Although colleagues at the Naval Observatory put forward the name Persephone, Christie insisted on it after discovering that Charon happened to be a Greek mythological figure.[9]Charon (/ˈ k ɛ r ə n/, Greek:Hades(Hades or Plouton, Greek: Πλ ο των, Plo ú t ō n). In Roman mythology, the Pluto was called Pluto.The name was officially adopted by the International Astronomical Union at the end of 1985 and announced on January 3, 1986.[11]
Charon, the ferry man of Styx, works of Alexander Litovchenko, a 19th century Russian painter
There is still a little debate about the preferred pronunciation of the name.Major English dictionaries, such as Merriam Webster andOxford DictionaryThey all use the classical pronunciation established for the mythical ferry man Charon, with the sound "k".[12][13]When referring specifically to Pluto's moon Pluto, these only indicate Charon's "k" pronunciation.People who speak languages other than English, as well as many English speaking astronomers, follow this pronunciation.[14]
However, Christie herself pronounced the initial ch as "sh" sound (IPA/ʃ/) according to the name of his wife Charlene.Therefore, as a recognition of Christie, sometimes it can even be seen as a joke. When astronomers speak English, they often use "sh" as the initial pronunciation of Charon,[14-16]This is also the official pronunciation used by NASA and the New Horizons team.[17]
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Robin Canup published in 2005《science》The simulation research in the magazine shows that Pluto may have been formed by the collision about 4.5 billion years ago, just like the formation of the Earth and the moonBig collision hypothesisSame.In this model, a hugeKuiper beltThe celestial body crashed into Pluto at high speed, destroying itself and blasting out Pluto's outer mantle, while Pluto 1 was formed by the merger of these fragments.[18]However, this situation will lead scientists to find more ice material for Pluto, and more rock material for Pluto.Later, it was thought that Pluto and Pluto might be two colliding objects before they revolved around each other.The collision degree should be enough to vaporizemethane（CHfour）And other volatile ice substances, but not enough to cause any of them to be destroyed.Pluto and Pluto are very similar in density, which means that they did not disintegrate completely when the impact occurred.[19]
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Pluto and Pluto circle each other every 6.387 days.The two objects are gravitationally locked to each other, so they maintain the same orientation.This is mutualTidal locking In contrast, the tide locking of the earth to the moon is different. One side of the moon always faces the earth, but the earth is not locked by the moon.The average distance between Pluto and Pluto is 19570 kilometers (12160 miles).The discovery of Pluto allows astronomers to accurately calculate the overall mass of Pluto's system. Mutual occultation reveals their size, but it is impossible to calculate the separate mass of these two objects.It was not until the discovery of Pluto's outer moons in late 2005 that their masses could be calculated.According to the detailed information of the outer satellite orbit, Pluto's mass is 12% of Pluto's.[20]
physical property
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Pluto has a diameter of 1212 kilometers (753 miles), although it is only half the diameter of Pluto,[3][19]But it's a dwarf planetCeresIt is the twelfth largest natural satellite in the solar system.The slow rotation of Pluto means that if Pluto is big enough to be in theHydrostatic balanceState, there should be almost no stretching or tidal deformation.As a result, New Horizons could not find any deviation between Triton and the ideal sphere through observation.Saturn's moon Iapetus is similar in size to Pluto, but obviouslyOblatenessIt can be traced back to its early history.The low oblateness of Pluto may mean that it is in hydrostatic equilibrium, or just that its orbit is close to the early relatively warm period of its history.[21]
The rotating center of mass of Pluto and Pluto is outside Pluto
The mass of Pluto is about 1/45 of that of the moon, but it is the largest satellite in the solar system in terms of the size ratio of its satellite to its planet.Pluto's mass is only about 8 times that of Pluto, while the mass of the Earth is 81 times that of the Moon, and Jupiter is thousands of times larger than its largest satellite.According to the mass update of the New Horizon observation, the mass ratio of Pluto to Pluto is 0.1218:1.This is much larger than the mass ratio of the moon to the earth (0.0123:1).Due to the high mass ratio, the center of mass is outside the radius of Pluto, and Pluto Pluto 1 system is informally called a double dwarf planet.Due to the uniqueness of four smaller satellites orbiting two larger bodies, Pluto Pluto 1 system can be used to study the stability of the orbits of planets orbiting binary stars.[22]
Planetary interior
Possible internal composition of Hades One
Using the volume and mass of Triton, its density can be calculated as 1.702 ± 0.017g/cm3,[3]Therefore, it can be determined that the density of Pluto is slightly lower than that of Pluto, suggesting that 55% of the rocks and 45% of the ice are composed (± 5%), while Pluto is about 70% of the rocks.The difference is far lower than that of most satellites suspected to have been formed by collision.Before New Horizons flew by, there were two contradictory theories about the internal structure of Pluto: some scientists believed that Pluto was an internally differentiated celestial body like Pluto, with a rock core and an icy mantle, while others believed that Pluto never differentiated internally.[23]In 2007, evidence supporting the former position was found, whenGemini Observatory An active low-temperature fountain was found by observing the ammonia hydrate and crystal on the surface of Triton.The fact that ice is still in crystalline form indicates that it was deposited recently, because solar radiation can degrade it into amorphous state in about 30000 years.[24]
Planetary surface
Pluto's surface is composed of nitrogen and methane ice, while Pluto's surface is different from that of Pluto, which seems to be dominated by less volatile water ice.In 2007, the ammonia hydrate and crystal patches observed by Gemini Observatory on the surface of Triton indicate that there are active low-temperature fountains andIce volcano。[24-25]Its surface atmosphere is only about 0.1MillibarAbout one ten thousandth of the atmospheric concentration on the earth's surface, which is nearly nonexistent. At present, scientists are trying to study the surface of Triton to determine whether the satellite hasatmosphere。
The luminosity mapping on the surface of Triton shows that the albedo varies withlatitudeThe trend of change is that the equatorial belt is bright and the poles are dark.The New Vision team informally called the Arctic region "Mordor" (from "The Lord of the Rings"), which is a large dark area.[26-28]The best explanation for this phenomenon is that they are formed by condensation of gases escaping from Pluto's atmosphere.These gases (includingnitrogen，carbon monoxideandmethane）Condensate into solid form.When these ice are exposed to solar radiation, they will have chemical reactions and form various reddishTorin(Tholins, organic macromolecule mixture).Later, with the seasonal change of Triton, the region was heated by the sun again, and the temperature at the pole rose to - 213 ° C, resulting in volatile mattersublimationAnd escaped from the underworld, leaving only Torin.Over millions of years, the remaining tolin will accumulate into a thick layer, covering the ice crust.[29]In addition to the Mordor area, New Horizons also found extensive geological evidence in the past, indicating that Mimas may be different;[27]In particular, there are fewer meteorite craters in the southern hemisphere than in the northern hemisphere, and the terrain is relatively low, which indicates that a large-scale reshaping surface event may have occurred.Caused by partially or completely frozen internal oceans - occurring at some time in the past, eliminating many earlier impact craters.[30]
Mordor (Mordor), the dark area of the north pole of Hades One, is named after the Lord of the Rings
In 2018, the International Astronomical Union willImpact craterNamed Revati, he is an Indian epic《Mahabharata》Role in.[31]There are a series of broad grabens or canyons on the surface of Triton, such as Serenity Chasma, which extends at least 1000 kilometers (620 miles) as the equatorial belt.Argo Chasma may reach 9 kilometers (6 miles) deep, and its steep cliffs mayTianwei FiveOn MirandaVerona Rupes (Verona Rupes), the highest cliff in the solar system.[32]
An enhanced color map of the world of Triton taken by New Horizons
In the photos released by New Horizons, an unusual surface feature fascinated and puzzled the team of scientists involved in this task.This image shows a mountain rising from a low spot.Jeff Moore of NASA Ames Research Center said in a statement that this is "a mountain in a trench".He added: "This is a geological feature that shocked and puzzled geologists." New Horizons took this picture at a distance of 79000 km (49000 miles).[33-34]
Surface details of Mieidon taken by New Horizons
Observation and detection
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Since the first blurred satellite image, the Hubble Space Telescope took the first image of Pluto and Pluto breaking down into separate disks in the 1990s.The telescope took the best but not high quality images of the satellite at that time.In 1994, the clearest picture of the Pluto Pluto Triton system showed two different and definite circles.The image was taken by the Hubble Space Telescope's Weak Object Camera (FOC), which was 4.4 billion kilometers (2.6 billion miles) away from the Earth.[35]Later,adaptive optics Technological advances have made it possible to use ground-based telescopes to separate Pluto and Pluto into separate circles.[10]In June 2015, the New Horizons spacecraft took continuous images when approaching Pluto Pluto 1 system. These images were combined in the form of animation, which is the best picture of Pluto 1 so far.In July 2015, the New Horizons spacecraft approached Pluto system, which is the only spacecraft that has visited and studied Pluto to date.When New Horizons was closest to Pluto's system, James Christy, the discoverer of Pluto, and Clyde, the discoverer of Pluto·ThompsonClyde Tombaugh's children were invited to the Johns Hopkins Applied Physics Laboratory.
Phobos (left) and Pluto (right) photographed by New Horizons
Status dispute
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The center of mass of Pluto Pluto 1 lies outside these two celestial bodies.Therefore, there is no case that one of them really orbits the other, and Pluto's mass is 12.2% of Pluto's, so some people think that Pluto and Pluto should be considered as part of the binary system respectively.The International Astronomical Union (IAU) pointed out that Pluto is only a satellite of Pluto, but the idea of classifying Pluto itself as a dwarf planet may be considered later.[36]
For the first time, the International Astronomical Union (IAU) set the standards for planets at its 2006 annual meeting.It is suggested that the planets must revolve around the sun and have enough gravity to make themselves into spheres.In a multi body system that revolves around a star, if the main body is a planet, the secondary body is also spherical and meets the condition that the gravitational center between the main body and the secondary body is not inside the main body, it can also be called a planet.If Pluto is still a planet, Pluto meets this condition to become a planet. However, as Pluto is downgraded to a dwarf planet, whether the above definition of multi body system is applicable to a dwarf planet makes the identity of Pluto very unclear.[37]To date, Pluto has not been included in the list of dwarf planets approved by the International Astronomical Union.[36]If Pluto is defined as a dwarf planet, the tide will accelerate graduallyMoonFar away from the Earth will cause the Earth Moon center of mass not to be inside the Earth, and then the moon will also be classified as a planet.[37]
Other moons of PlutoHell Guard II、Hydra 、Kerberos andHell Guard FiveThey also surround the same center of gravity, but they are not large enough and are not spherical, so they are only recognized as the satellites of Pluto (or the satellites of Pluto - Pluto 1 system).[38]
Merged picture of Pluto and Pluto (distance is not true)
