Pluto issolar systemOne ofdwarf planet。It is found that there are five satellites, namely, Caron, Nix, Hydra, Coporos and Styx.In 2006,International Astronomical UnionPluto and Charon are among the dwarf planets.Pluto and Charon are a pair of double planets in the solar system. The ratio of their diameters is about 3:1. The gravitational center is located in the free space on the outer surface of Pluto, so their movements are like dancing in the sky.
Five are known.The first one was discovered by Christie in 1978. It was temporarily numbered 1978P1 at that time, and is now named Karon. It is also called Minwei I in Chinese.Its discovery made people get the accurate value of Pluto's mass for the first time, established Pluto's position as a major planet, and led to a new classification method of planets, which is of great significance.After several calculations, Pluto's radius is 580 ± 50 kilometers, more than half of Pluto's, and it is the satellite with the largest proportion of planets in the solar system.It can be estimated that its mass is 1.3 × 10twenty-oneKg.Pluto is located in the orbit of Pluto's geostationary satellite. The center distance between the two is 19000 kilometers, so it is a natural geostationary satellite in the solar system. Not only does Pluto always face Pluto on the same side, Pluto also faces Pluto on the same side all the time.The rotation period of Pluto I, the revolution period around Pluto and the rotation period of Pluto are 6.3867 days.
On July 7, 2012, the fifth satellitehubble space telescope It is found that the code is S/2012 (134340) 1 (or P5).
Basic parameters
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Arranged according to the distance from Pluto.amongboldIt represents that the star is a satellite that reaches the hydrodynamic balance (sphere).Some satellites that are not spherical will use numbers like "60 × 40 × 34" to represent their lengths on the three axes.The reference system of inclination is Pluto's equator.The center of mass of Pluto's system is not within Pluto, so all orbital data are based on the center of mass, including Pluto itself.
Pluto satellite system
S/N
Chinese name
English name
diameter
Mass (× 10nineteenkg）
Semi major axis (km)
Revolution period (d)
Eccentricity
Inclination (°)
Year of discovery
00
Pluto
Pluto
2376.6±3.2
1305±7
two thousand and thirty-five
six point three eight seven two three zero
zero point zero two two
zero point zero zero one
one thousand nine hundred and thirty
01
Charon
Charon
1212±1
158.7±1.5
17536±3
six point three eight seven two three zero
zero point zero two two
zero point zero zero one
one thousand nine hundred and seventy-eight
02
Hell Guard Five
Styx
16×9×8
zero point zero zero zero seven five
42656±78
20.16155±0.00027
zero point zero zero five seven nine
zero point eight one
two thousand and twelve
03
Hell Guard II
Nix
49.8×33.2×31.1
0.005±0.004
48694±3
24.85463±0.00003
zero point zero zero two zero four
zero point one nine five
two thousand and five
04
Kerberos
Kerberos
19×10×19
0.0016±0.0009
57783±19
32.16756±0.00014
zero point zero zero three two eight
zero point three eight nine
two thousand and eleven
05
Hydra
Hydra
50.9×36.1×30.9
0.005±0.004
64738±3
38.20177±0.00003
zero point zero zero five eight six
zero point two one two
two thousand and five
Specific introduction
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Charon
Minwei, also known as Karon, was discovered in 1978.Caron was a draughtsman of Pluto, the god of the underworld in Roman mythology. He asked the dead for money to row across the Styx River for them.In 2005, two more Pluto moons were discovered: Pluto II (Nix) and Pluto III (Hydra).According to the current definition, Pluto may be the largest moon of Pluto, or it may form a double dwarf planet with Pluto.
The New Horizons mission visited Pluto and Charon in 2015.
Charon
The name of Charon is easily confused with Chiron, another small object in the solar system (2060).
The discovery of the keeper
Caron was discovered on June 22, 1978, when the astronomer Jim Christy inspected the images of a group of photographic negatives of Pluto a month ago at a high magnification.Christie noticed that a small bulge would appear periodically.Later, the negative film dated back to April 29, 1965 also confirmed the bulge.
Charon
Naming of Hades One
The original temporary name of Charon was S/1978 P 1, which was given according to the new naming rules formulated by the General Assembly at that time.Later, Christie called it "Charon", but not until 1985International Astronomical UnionOnly then did they agree that this name was an official name.In Greek mythology, Caron is the ferry for the dead, and is closely linked with Hades (Pluto in Roman mythology) in the mythological map.
Although the traditional English pronunciation in the myth picture is a hard k sound, Christie changed the pronunciation of ch to that of the satellite, and then his wife Charlene's nickname was "Char" (carbon gray), and the pronunciation of sh was also popular in the astronomical world, and everyone used this pronunciation as the custom.In European languages other than English, they still use the mythical pronunciation, saying ch.
The physical properties of MikyoThe diameter of Cajon is about 1212 kilometers (750 miles), which is about half of Pluto. Its surface area is about 4580000 square kilometers. The surface is covered with frozen nitrogen and methane.Unlike Pluto, the surface of Charon may appear to be frozen, nonvolatile water.The surface temperature of Cajon is about - 230 ℃, and the density is 1.63 g/cm3. It shows that more than half of the composition is rock, while the ice is a little less than half.Its surface atmosphere is only about 0.1 mbar, which is one ten thousandth of the atmospheric concentration on the earth's surface, and it is nearly nonexistent. At present, scientists are trying to study the surface of Mimas to determine whether the satellite has an atmosphere.
Charon
Orbital characteristics of MibosThe surface of Pluto and Charon, from the change in luminosity, is confirmed to be in the mutual masking period.Pluto and Charon are inTidal locking In a 6.387 day period, they will circle each other at the same position forever.The average distance between the two is 19570 kilometers (12163 miles).Caron's discovery enables astronomers to accurately measure the total mass of Pluto's system, while mutual masking can calculate their respective sizes (diameters), but individual masses can only be estimated. Until the discovery of Pluto's outer satellites in 2005, it was revealed that Caron's mass was about 11.65% of Pluto's according to the orbital details of the outer satellites,It also shows that the density is 1.65 ± 0.06 grams/cubic centimeter, and it is suggested that 55 ± 5% is "rock" and 45% is ice.Pluto has a high density, about 70% of "rocks".The formation of Phobos was simulated by Robin Kanji and published in 2005. It is suggested that Charon was formed in the great collision about 4.5 billion years ago, which is very similar to the situation of the Earth and the moon.In this model, a giant Kuiper Belt object crashed into Pluto at a high speed, destroying itself and blowing away most of Pluto's mantle, and Caron was formed from these fragments.However, such an impact should make Pluto more rocky than we found, while Charon would have more ice.Therefore, it is believed that Pluto and Charon were two different celestial bodies before the collision in orbit. Although the collision was fierce, it could only evaporate ice like methane, but it was not enough to cause disintegration.
Satellites or dwarf planetsThe center of mass of Pluto Charon falls outside these two celestial bodies, so one of them is not really orbiting the other, and the masses of the two can be compared with each other, so Charon is not suitable for being used as a satellite of Pluto.Instead, they should be double dwarf planets, which should be reclassified with Pluto.
stayInternational Astronomical UnionThere is a draft of the annual meeting in 2006, which suggests that planets must revolve around the sun and have enough gravity to make themselves into spheres.Under such a draft, Charon is qualified to be a planet, because the draft clearly defines the condition that the satellite is the center of gravity of the system must be inside the main celestial bodies.But the final reclassification classified Pluto as a dwarf planet, but there was no formal definition of the planet's satellite, making the identity of Caron very unclear.(So far, Charon has not been included in the list of dwarf planets approved by the International Astronomical Union.)
The International Astronomical Union's planetary standard stipulates that in a multi body system that revolves around a star, if the main body is a planet and the secondary body is spherical, and meets certain conditions, it can also be called a planet, that is, the gravity center between the main body and the secondary body is not inside the main body.So the star Charon meets this condition.
Pluto 2 (Nix) and Pluto 3 also surround the same center of gravity, but they are not big enough to be spherical, so they can be easily identified as Pluto's satellites.(Or, in other words, the satellite of Pluto Charon system)
If Pluto and Pluto 1 are completely closed, their distance from the center of mass is determined according to their mass relationship. According to the universal gravitation and its related formula, the period of Pluto around the center of mass is far shorter than that of Pluto 1 around the center of mass.But the actual observation shows that their periods are the same, which makes their systems unbalanced, so Pluto's extra force around the center of mass is around the sun.Pluto is a satellite, not a planet.
Hell Guard II
Hell Guard II
It was first observed by Pluto Companion Search Team through the Hubble Space Telescope in May 2005.Its photos were taken by the Hubble Space Telescope on May 15, 2005 and May 18, 2005;On May 15, 2005, after being confirmed and estimated, Max J. Mutchler announced the news of satellite discovery on October 31, 2005. It was initially numbered S/2005 P2, and was officially named Nix at the meeting of the International Astronomical Union in late June 2006. The name of the satellite was set off for Pluto in January 2006New Horizons (New Horizons) The first letter of the detector name is concept.
Observations show that it is similar to Charon, with an orbit radius of 50000 km and a cycle of 25 days around Pluto;It is estimated that its diameter is 32-145 km (more accurate data can be determined according to the albedo).The second keeper is 25% darker than the third keeper, so it may also be smaller.
Hydra
Hydra
It was first observed by Pluto's companion search team through the Hubble Space Telescope in May 2005.The photos were taken on May 15 and May 18 of the same year;On May 15, 2005, after being confirmed and estimated, the observer Max J. Mutchler announced the news of satellite discovery on October 31, 2005, which was temporarily numbered S/2005 P1. In late June 2006, it was officially named Hydra after the meeting of the International Astronomical Union. The concept of the name was taken from the New Horizons flying to Pluto in January 2006The second letter H of the detector name.
Observations show that it is similar to Charon, with an orbit radius of about 65000 km and a cycle of 38 days around Pluto.It is estimated that its diameter is 52-160 km.Xudra (Pluto III) is 25% brighter than Pluto II, so it may also be larger.
Kerberos
Astronomers useHubble Space TelescopeThe discovery of Pluto's fourth moon.This small satellite was temporarily numbered P4. On July 2, 2013, it was officially named "Coporos" by the American scientific research organization "Search for Alien Civilization Institute", also known as Pluto.In fact, this was an unintentional work. At that time, Hubble's original purpose was to see whether Pluto had a halo.Copporos is the watchdog of hell with three heads in the myth.
The new moon discovered this time is the smallest one orbiting Pluto.Its diameter is estimated to be between 13 and 34 kilometers.In contrast, Pluto's largest moon Charon has a diameter of 1043 kilometers.The diameter of the other two small satellites, Nix and Hydra, is also between 32 and 113 kilometers.
Mark Showalter, from SETI in Mountain View, California, said: "It's very incredible. The powerful resolution of the Hubble Space Telescope allows us to distinguish the existence of this satellite so clearly at a distance of 5 billion kilometers."
This observation is one of the contents of NASA's observation plan to support its "New Horizons" project. This probe will fly over the Pluto system in 2015.This close inspection of Pluto and its satellite system will help us to provide more information about this marginal zone of the solar system.For better planning the work plan of the New Horizon probe near Pluto's orbit, Hubble's mapping and imaging of Pluto's surface and the discovery of new satellites will have inestimable significance.
Alan Stern, the chief scientist of the New Horizon project and from the Southwest Research Institute of NASA, said: "This is an incredible discovery. Since we know that Pluto has such a new satellite, we can arrange a detailed observation of Pluto during a close inspection."
The orbit of this new satellite lies between Nix and Hydra, which were also discovered by the Hubble Space Telescope in 2005.Caron was founded in 1978 byUS Naval ObservatoryIt was discovered, but the observation ability at that time was only limited, and because Pluto and Charon were too close to each other, they could not be separated, and only Pluto seemed to have a "bulge" on its surface.It was not until the 1990s after the launch of the Hubble Space Telescope that the two celestial bodies were finally separated clearly with its powerful resolution.
Astronomers believe that Pluto's satellite system was created after it collided with a planet mass object in the early solar system.After the impact, a large amount of material splashed into Pluto's orbit and gradually condensed to form a satellite.
Similarly, according to the returned analysis data of lunar soil and rock samples, geologists got a theory that the moon was most likely formed by the condensation of the splashed materials after the collision between the Earth and a Mars sized object about 4.4 billion years ago.Scientists also doubt whether such an impact will form a halo around Pluto, but Hubble's observations have not found any clues to the existence of such a halo.
Jon Morse, the director of the astrophysics department at NASA headquarters in Washington, said, "This amazing discovery is the best proof of the power of the Hubble Space Telescope as a general observation platform. It is enough to make amazing and unexpected discoveries."
Pluto was first discovered in an image taken by the Hubble Space Telescope with the wide-angle camera - 3 on June 28.Later confirmed in the images taken by Hubble on July 3 and July 18.The reason why the new satellite could not be found in the previous shooting was that the exposure time used by Hubble was too short.In fact, looking back, the small satellite was already photographed in a Hubble image taken in 2006, but was ignored by analysts at that time because the satellite in that image was very weak and could hardly be distinguished from noise.
The Hubble Space Telescope is a large-scale international cooperation project between NASA and the European Space Agency. The NASA Goddard Space Flight Center in Greenbank, Maryland, is responsible for the daily operation management, while the NASA Goddard Space Flight Center in BaltimoreSpace Telescope Research InstituteIs responsible for the operation of scientific projects of the telescope.The Institute is operated with the assistance of the American Association of University Astronomers (AURA).
Hell Guard Five
Astronomers passed the Hubble Telescope on July 7, 2012Wide angle planetary cameraOn the 3rd, Pluto's fifth satellite S/2012 (134340) 1, also known as P5, was discovered. In 2013, the American Scientific Research Organization "Search for Alien Civilization Institute" was named "Styx". By collecting the photo information taken by its astronomical observatory, the orbital information of the satellite was calculated.Styx is a mythical river that flows into hell.
P5 inPlutoThe distance from Pluto in the satellite system ofCharon The average diameter is about 10-25km, the diameter of the revolution track is about 95000km, and the revolution period is about 20.2 days.[1]
