The existence of Pluto was theoretically predicted by American astronomer Percival Lovell in 1915. Discovered by Clyde Tombaugh in 1930. After the discovery of Pluto, scientists used indirect methods to study the planet. So, if Mars is conditionally moved to the distance of Pluto, then it will be illuminated by the Sun 625 times weaker. In addition, due to its distance from the Earth, it will shine at us even 1600 times weaker. As a result, the brightness of Mars will decrease by 15 magnitudes, i.e. will be the same as Pluto's. Consequently, Pluto is comparable in size to Mars, and if its albedo (reflectivity) is less than that of Mars, then to the Earth.
Therefore, for 40 years, Pluto was considered equal in size and mass to the Earth, or, in extreme cases, to Mars. But in April 1965, Pluto passed close to a 15th magnitude star, so close that if its diameter exceeded 5500 km, it would have completely obscured this star. In fact, the star was not closed. This meant that Pluto's diameter was less than 5,500 km.
Back in the 50-60s of our century, it was established that the brightness of the most distant planet in the solar system periodically changes. Measurements showed that the period of brightness changes is 6 days 9 hours 17 minutes. This value was accepted as the rotation period of Pluto, but it was not only the rotation period of Pluto itself. Pluto is a faint object, but there are quite a few "good" photographs of it in which Pluto appears as a shapeless, blurry speck. These photographs were published in scientific publications and lay in the closets and on the desks of scientists. And, as sometimes happens, along with the photographs on the tables lay the future discovery. All you had to do was look closely: the pictures of the planet looked like a slightly elongated speck, oriented differently. Unfortunately, until 1978 no one paid attention to this. No one imagined that a close double planet was hidden behind the elongation of the spot! Both bodies have similar sizes, so it is more correct to talk about a double planet or a system of two satellites, and not about a planet and a satellite. Charon constantly faces Pluto with one side, just like the Moon faces Earth. But the ideality of this synchronously moving pair lies in the fact that Pluto is always turned towards Charon by the same hemisphere. In other words, the periods of rotation of both bodies around their axes and the orbital period of Charon coincide, it is equal to 6.4 days.
Pluto's satellite is so large and so close to the planet that it was only possible to separate them using interferometry methods. The period of 6.387 days turned out to be the period of mutual revolution of the components (or the period of their rotation around a common barycenter - the center of mass).
A new stage in the research of Pluto began in 1978, when astronomer James Christie at the Naval Observatory in the same Flagstaff, using a one and a half meter reflector, discovered its dim satellite, which received the name Charon (according to ancient Greek mythology, this was the name of the carrier who ferried the souls of the dead through the rivers of the underground). kingdoms). Based on the period of revolution of the satellite around the planet, astronomers calculated the mass of Pluto - 1.3 * 10 22 kg, which is approximately 1/500 of the mass of the Earth and 1/6 of the mass of the Moon. Based on estimates of the mass of the planet, it was possible to find the distance between Pluto and Charon using the value of the period. On a cosmic scale, it turned out to be incredibly small - only 18-20 thousand km.
It remained to determine the exact sizes of Pluto and Charon. And here the scientists were extremely lucky. Charon's orbit is located in such a way that once every 124 years (half the period of Pluto's revolution around the Sun), a five-year period begins for earthly observers, when every 6.4 days Charon passes in front of Pluto's disk and at the same interval (but for 3.2 days sooner or later) hides behind the planet. The next series of such passages and coverings occurred in 1985-90. Observations of these phenomena made it possible to accurately determine the diameters of Pluto (2290 km) and Charon (1186 km). An independent determination of the size of Pluto was made from observations of its coverage of the star on June 9, 1988. The average density of both bodies was calculated - 1800 kg/m 3. This is less than the density of rock, but greater than the density of ice. Apparently Pluto is made up of both (Pluto is made up of 70% mixed rock and rock and 30% frozen water).
Thus, Pluto is the smallest planet among the large planets. In addition, it (and not the Earth) has the most massive satellite (in terms of satellite/planet mass ratio). Charon is 1/8-1/10 the mass of Pluto. Back in 1976, Dale Cruikshank and his colleagues from the University of Hawaii (USA) discovered a rarefied atmosphere of methane (CH 4) near Pluto. Further research confirmed their discovery. The pressure of this atmosphere at the surface of the planet is 7 thousand times less than the atmospheric pressure at the surface of the Earth.
Pluto's surface is covered with methane ice and is therefore grayish in contrast to the reddish Charon, which is dominated by ordinary rock and water ice.
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| This is the clearest image of Pluto and Charon to date. The image was taken on February 21, 1994 (Hubble), when the planet was at a distance of 4.4 billion km from the Earth, which is approximately 30 times the radius of the Earth's orbit. Using data from the Hubble telescope, a rough map of Pluto was created. |
| LOST WORLD |
| Images of Pluto and its moons taken by the Hubble telescope on February 15, 2006. New images of the Pluto system in different spectral ranges have shown that the planet's satellites have almost the same color and reflect sunlight with the same intensities. |
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For several years before and after perihelion, Pluto is closer to the Sun than Neptune. This period can be considered "summer" for Pluto. Nevertheless, the temperature at the surface of the planet at this time ranges (according to various estimates) from 45 to 67 K (from -228 to -206 ° C). The last time Pluto passed its perihelion was on September 9, 1989. In 124 years, when it is at aphelion, the influx of solar heat will decrease threefold and the temperature will drop to 32-50 K.
In 1995, American scientists, using special equipment mounted on the orbiting Hubble Space Telescope, photographed the entire surface of Pluto and compiled its map. The planet's north pole is covered with a cap of frozen gases. In other areas, light and dark areas are interspersed with bright elongated stripes. It is assumed that this is due to frost deposits: the oldest of them, which had time to decompose under the influence of ultraviolet radiation from the Sun, have a darker color, and the more recent ones have a light color.
The orbits of Pluto and Neptune lie in different planes, so they do not intersect, as you might think when looking at a diagram of the Solar System, where all orbits are projected onto the ecliptic plane. Moreover, since the orbital periods of Neptune and Pluto are in the ratio 2:3, the motion of these planets occurs, as they say, in resonance, and the distance between them is never less than 18 AU. Even Uranus sometimes comes closer to Pluto than Neptune: it can be at 14 AU. from the most distant planet.
In 1936, the English astronomer Raymond Littleton hypothesized that Pluto was a satellite of Neptune in the past. But it has not yet been possible to convincingly substantiate it. Pluto and Charon are a distant, lost world living its own life. Methane ice evaporates, maintaining the planet's thin atmosphere. Gases carry tiny pieces of ice into the atmosphere, creating a haze of aerosols. Meteorites fall on Pluto. A comet rushes past. Against the background of the constellations familiar to us, Charon shines dimly...
In 2005, the space telescope. Hubble reliably detected the presence of two more components of the Pluto system. They received temporary designations S/2005 P1 and S/2005 P2 and became candidates for the satellites of Pluto. The candidates move counterclockwise at a distance of 44 thousand km from Pluto. They are visible in these deep space telescope images taken three days apart. These small satellites were also discovered in space telescope images in 2002, and observations are planned to be made in February next year (2006) to confirm this discovery. Compared to the sizes of Pluto and Charon - 2300 km and 1300 km respectively - the moons are estimated to be between 60 and 200 km across. The satellites' orbits lie within the Kuiper Belt, a region beyond the orbit of Neptune in which the Pluto system is the first known quadruple system.
Pluto's two moons, discovered in 2005, were created at the same time as Charon, the planet's largest moon, during a massive cosmic collision. The group of astronomers who announced the discovery in November spent six months testing their findings and have now published their work with official confirmation, as well as a new hypothesis about the origin of distant celestial bodies. Robin Canup from the American South-west Research Institute performed a computer simulation of the birth of Charon, Pluto's moon. The Pluto-Charon pair is unique in our solar system because Charon's diameter is about half the size of the planet it orbits, whereas most moons are only a few percent the size of their planets. Previously, astronomers successfully simulated on a computer how the collision of the young Earth and a body the size of Mars gave birth to the Moon (which was confirmed by precise calculations and analysis of lunar soil). A similar theory has been put forward regarding the Pluto-Charon system; researchers believe that Pluto's gravity may have captured a "stray" object from the Kuiper Belt.
Mr. Kanap created a computer model that demonstrated for the first time that the Charon impact theory was very likely. The results show that the impact of an object measuring between 1,600 and 2,000 kilometers traveling at a speed of approximately one kilometer per second could have spawned Pluto's moon Charon. The impact likely created a disk of debris around Pluto, from which Charon later “glued together.” Astronomers were able to calculate that Charon's density is 1.71 times the density of water, that is, it is a rock-ice body. The version of the cataclysm is supported by consistent trajectories and a similar density of satellites. It is known that all three bodies revolve in the same plane in circular orbits, and while Charon makes one revolution, the second satellite manages to make exactly two, and the third - three. Scientists do not rule out that in the same plane there is a ring of space debris - small debris left after an ancient cataclysm. It is not yet possible to verify this - even Pluto and Charon themselves are difficult to distinguish from the Earth or from near-Earth space, and even more so the new satellites, the diameter of which (depending on the albedo) is no less than 46-61 kilometers and no more than 137-167 km. Pluto's moons S/2005P1 and S/2005P2 orbit at a distance of 64,700 km (+/- 850 km) and 49,400 km (+/- 600 km) from the planet, respectively. The circulation period of P1 is about 38 days, P2 is about 25 days. The orbits of P1 and P2 are probably in resonance with the orbit of Charon. Observations have shown that within the orbits of the three already discovered satellites there are no other satellites, up to a brightness 40 times less than that of P1 and P2. This means, firstly, that Pluto’s system is extremely compact, and, secondly, it is quite “empty” - Pluto has no other large satellites.
For the same reason, Pluto and its related bodies are known relatively recently - the planet was discovered in 1930, and its main satellite in 1978. In addition to the Pluto system, astronomers in recent decades have discovered a family of “trans-Neptunian” objects that together form the Kuiper Belt. The authors of the discovery suggest that other “multiple” systems of asteroids (or planetoids) may be concentrated there - at least, a pair of satellites have already been discovered for the object 2003 EL61. According to current estimates, at least 20% of Kuiper Belt objects have satellites. Probably many of them have several such satellites. The number of Kuiper belt objects is now roughly estimated at 40 thousand, but the fact of the impact origin of Pluto’s satellites can lead to a significant revision of the frequency of collisions, and, consequently, the number of celestial bodies. Taking into account other strange features of Kuiper belt objects, we should expect the emergence of the most unexpected hypotheses.
New images of the Pluto system in different spectral ranges showed that the planet's satellites have almost the same color and reflect sunlight with the same intensities at different wavelengths of the visible spectrum (observations were carried out with blue and red-green filters). All three of Pluto's moons (Charon, S/2005 P1 and S/2005 P2) also share a common orbital plane. All this confirms the previously stated assumption that all satellites were formed simultaneously as a result of the impact process. Moreover, it has become possible to make assumptions about the probable nature of the surface of the new small satellites of Pluto, discovered last year 2005. Since Charon is covered with water ice, and the spectral characteristics of all three satellites are very close to each other, most likely they are all covered with ordinary ice. Interestingly, spectral properties similar to the satellites of Pluto are also characteristic of the Earth’s satellite, the Moon. Pluto itself is unlike any of its satellites and is distinguished by a characteristic reddish tint, apparently due to the presence of methane ice on its surface.
Characteristics The average distance from the Sun is 39.23 AU. Pluto has the largest eccentricity among the planets of the Solar System: e = 0.244. Thus, Pluto has the most elongated orbit. The point of the orbit closest to the Sun is at a distance of 4447 million km from the Sun, and the most distant point is at a distance of 7392 million km. From 1979 to 1999, Pluto was closer to the Sun than Neptune, making it the eighth planet during that period rather than the ninth. The average speed of Pluto's orbital motion is 4.8 km/s, the inclination of the orbital plane to the ecliptic plane is 17.2°. Since its opening in 1930, it has not yet completed half a full revolution. The period of rotation around the axis is 6.39 days (153.29 hours). The inclination of the equator to the orbital plane is 122.5°. Gravity acceleration g = 0.07g = 0.78 m/s2. The planet appears to be composed of ice mixed with rock. Pluto's albedo is 0.3. Pluto has a rarefied atmosphere in which methane, argon, and neon are detected (according to some sources, the atmosphere is made of nitrogen with carbon monoxide and methane). Pluto's orbit is highly elongated: the planet is currently moving away from the Sun. In this case, Pluto's atmosphere will soon solidify and fall onto its surface in the form of snow (solid methane). Only after two hundred years will Pluto again be at its closest distance from the Sun, and its atmosphere can again be explored. Since Pluto is so small and has low density, for some time they even wanted to demote it from the ranks of the planets of the solar system, but the International Astronomical Union (IAU) issued a statement that Pluto’s status as a planet would not be changed. Pluto is smaller than the seven satellites of the solar system planets: the Moon, Io, Europa, Ganymede, Callisto, Titan and Triton. Pluto is the only planet not visited by any spacecraft. Even the Hubble Space Telescope can only resolve the largest features on its surface. |
In the solar system there are planets so small that they are called Lilliputians. This includes Pluto. But even small planets have satellites. Her largest companion is Charon. But he is not the only one of his kind. There are others too. They are, of course, not so significant, but they are also of great importance.
In this article we will look at the features of Pluto and find out what Charon, the satellite of this planet, is. Let's also talk about the other, smaller satellites.
Until 2006, Pluto stood on a par with the main planets of the solar system and was a full-fledged unit.
Now it was given the name dwarf planet, after which they began to believe that it is the largest object in the dark disk-shaped zone.
One day, it became clear to scientists that Pluto is not a unique object in its environment, like all the other planets located in the Solar System. And that more than one such object can be discovered if you study the space beyond the orbit belonging to Neptune. And soon a certain body was indeed discovered, called Eris. It was a trans-Neptunian object that can be compared to Pluto. After this discovery, it became clear that the world, in fact, lacks the definition of a planet. And in 2006, a definition was approved that included three positions. According to it, those space objects that correspond to only two out of three positions are called a dwarf planet. Pluto is one of these.
It got its name from an eleven-year-old girl who decided that the name of the god of the underworld was suitable for a distant, perhaps cold and dark planet, and told her grandfather about it. And the grandfather already conveyed his granddaughter’s wish to the observatory, where it was finally approved.
In 2006, a spacecraft called New Horizons was launched towards the planet Pluto. It was the month of January. This device flew up to the planet at a distance of 12 thousand km and accumulated a huge amount of information about it. All this data is gradually transferred to scientists. This is due to the too slow transmission of information over such significant distances.
Features of the planet
Pluto has the shape of a perfect sphere. This discovery came as a surprise, as did the discovery of various landforms on the surface.
Moreover, there are extended areas on the planet that are completely devoid of impact craters. It is also known that Pluto’s glaciers are unevenly distributed over its surface, but it is still not clear why.
The planet Pluto and the satellite Charon, like other small satellites, are quite far removed from the Earth. Therefore, they have not been studied very well. There is an assumption that the surface of this planet has a rocky base, which is covered with water ice, also frozen methane and nitrogen. It is the products resulting from the photodissociation of methane that color the planet red.
Rotating in its orbit, which is far from a circle, Pluto can either get very close to the Sun, or, conversely, move away to a great distance. As it approaches, glaciers melt and an atmosphere consisting of methane and nitrogen forms around the planet. The further the planet moves away from the Sun, the smaller the atmosphere becomes, and eventually only a small haze remains, which, when viewed with the naked eye, has a red tint. This happens because the glaciers are freezing again.
Moons of Pluto. Charon and the planet's small satellites
Pluto has five natural satellites. The largest satellite, Charon, was discovered in 1978. Two smaller moons, named Nikta and Hydra, were seen in 2005.
Kerber was next. Its discovery occurred thanks to the Hubble telescope in 2011. And finally, in 2012, scientists discovered the presence of a fifth satellite of Pluto, which was named Styx. All the names of the satellites in one way or another refer to the underworld of Greek mythology.
Charon is a satellite of the planet Pluto
Charon got its name in honor of the carrier of the souls of dead people from the myths of Old Greece. It was discovered by US astrophysicist James Christie. This happened at the Naval Observatory in 1978.
This satellite is very large. Its size is equal to half the size of Pluto itself. The distance separating it from the planet it accompanies is almost 20 thousand km. This is approximately the same as from London to Sydney.
Charon is a satellite of Pluto, which many scientists have come to consider as a minor component of a binary system of planets. It was even given the name Pluto 1. The rotation periods of Pluto and Charon are the same. Thanks to this phenomenon, they always face each other with the same side. This phenomenon even got its own name - tidal lock.
Surface and composition of the satellite
The satellite Charon differs in its composition from Pluto. Unlike the planet, it is covered not by nitrogen, but by water ice. This is due to the fact that its surface temperature is 220 degrees Celsius below zero. But also the reasons for this composition include the fact that Charon is not so massive as to retain volatile compounds. The color of the satellite is more neutral, grayish. According to the existing theory, Charon was formed from fragments of Pluto itself that found themselves in orbit. Also, many scientists believe that the atmosphere of Pluto and Charon is connected.
Satellite Nikta
Charon is Pluto's largest moon, but there are others. One of them is Nikta. The discovery of this satellite was made public in 2005, on October 31. It owes its name to the goddess of the endless night.
The orbit in which the satellite is located is circular. There is no information yet about the exact dimensions of Nikta, but it is presumably smaller than Hydra. This is indicated by the darker color of the surface.
Hydra
If you look closely at the existing images, you can see that Hydra is located in the same plane as the satellite Charon. The distance between Pluto and Hydra is approximately 65 thousand km. There is no data on the exact size of this satellite. Scientists only assume that its diameter ranges from 52 to 160 km.
Hydra's surface is brighter than Nyx's. By about 25%. This means that its reflectivity is higher, which means its dimensions are larger. The satellite received its name in honor of a monster from Greek mythology with a hundred heads.
Kerberos and Styx
Pluto's fourth satellite is named Kerberos, also named after the mythical character of the underworld. Before the discovery of the fifth satellite, it was considered the smallest. Its estimated diameter is 13-34 kilometers.
The discovery of Kerberos was made thanks to the Hubble Space Telescope. The orbit in which the fourth satellite rotates is located between the orbits of Nix and Hydra. It orbits the planet in thirty-one days.
The smallest size is the fifth satellite Styx. Presumably its diameter is between 10 and 25 kilometers. This satellite rotates in an orbit located between the orbits of Charon and Nix. Its resonance with Charon is a ratio of one to three. It owes its name to the river, which in the myths of Old Greece separates two worlds - the living and the dead. It was also discovered by Hubble in June 2012.
Many issues have been addressed in this article. We found out which planet Charon is a satellite of, what are its features, size and composition. Now to the question: “Charon is a satellite of which planet?” - you will confidently answer: “Pluto.” By the way, one of the theories for the appearance of satellites around Pluto states that they were all formed as a result of the collision of this planet with some large object from the Kuiper belt. Unfortunately, today almost nothing more can be learned about these amazing objects. After all, Pluto is not only too far from Earth, but also does not have very good reflectivity.
Satellite Charon is almost half the size of Pluto. This small moon is so large that Pluto and Charon are sometimes called a double dwarf planetary system. The distance between them is 19,640 km (12,200 miles).
Satellite Charon - a distant guest
This new photograph of the region of Pluto's largest moon, Charon, reveals a unique feature: numerous depressions, which can be seen in the enlarged portion of the image on the right side.
The Hubble Space Telescope also photographed Pluto in 1994, when Pluto was at a distance of about 30 AU. from the earth. These photographs showed that Charon is grayer than Pluto (which has a red tint), indicating that they have different surface compositions and structures.
A high-resolution image of Charon taken from the Long Range Reconnaissance Imager on NASA's New Horizons spacecraft at its closest approach to the surface on July 14, 2015, with an enlarged color image from the Ralph/Multispectral Visual Imaging Camera (MVIC) superimposed.
A full revolution of Charon around Pluto takes 6.4 Earth days, and one revolution of Pluto (1 day on Pluto) takes 6.4 Earth days. Charon neither rises nor descends in the system's orbit. Pluto always stands on the same side of Charon - this is called tidal capture. Compared to most planets and moons, the Pluto-Charon system is tilted on its side, as is Uranus. Pluto's orbit is retrograde: it rotates in the opposite direction, from east to west (Uranus and Venus also have retrograde orbits).
Pluto's Moon Charon: Discovery
Pluto's moon Charon was discovered in 1978 when sharp-eyed astronomer James Christie noticed that images of Pluto were strangely elongated. The drop seemed to be spinning around Pluto. The direction of elongation is cyclical back and forth for 6.39 days - the rotation period of Pluto. Searching through archives of images of Pluto taken several years ago, Christie found more instances where Pluto appeared elongated. Additional images confirmed that he had discovered Pluto's first known moon.
But the moons of Jupiter were discovered much earlier. Galileo also discovered
Until 2006, Pluto, whose moon is Charon, was considered the ninth planet of the solar system. In connection with the discovery of many similar objects in the Kuiper belt, 2.5 thousand astronomers at the 26th Assembly of the International Astronomical Union classified Pluto as a dwarf planet.
The Mystery of the Ninth Planet
Observation of Neptune and analysis of its orbit showed that it alone cannot have such a strong impact on the movement of the seventh planet - Uranus. In 1906, the American philanthropist and amateur astronomer Percival Lowell launched the Planet X project to search for the ninth “inhabitant” of the Solar System. Various combinations of circumstances (a defect in the emulsion of a photographic plate, a coincidence of the image with the image of a star) allowed the mysterious planet to elude the optical instruments of astronomers until 1930.
Finally, an employee of the Lowell Observatory, 23-year-old K. Tombaugh, managed to obtain the necessary photographs and identify the movement of the desired object. Of the three options for the name of the planet - Minerva, Kronos and Pluto - the last one was chosen, proposed by the English schoolgirl Venice Burney.
Size matters
Calculating the exact physical parameters of the planet, due to its extremely large distance (on average 39.4 AU, or 5.85 billion km), is fraught with certain difficulties. The estimated orbit of Pluto has an inclination to the ecliptic of 17˚, which is unusual for planets. Over the past century, repeated attempts have been made to clarify the mass of the planet, and with each calculation the value turned out to be smaller and smaller. In 1978, Pluto's first satellite, Charon, was discovered. This made it possible to fairly accurately calculate the mass of the planet. It became clear that with the obtained value (0.2% of the mass of the Earth), the “lightweights” Pluto and Charon (this is a satellite) cannot have a serious impact on Uranus. What planet is still missing from this gravitational equation? The search for “Object X” resumed again with the same zeal, but did not bring any results.
To the relief of many, information transmitted to Earth by the Voyager 2 unmanned spacecraft in 1989, and updated calculations performed by NASA four years later, explained all the discrepancies in the movement of Uranus.
Ice world
Pluto can only be seen through a telescope as a 15th magnitude object. The period of revolution around the Sun is 248 years, around its axis (reverse rotation) - 6.4 days. Spectral analysis of the planet shows that its surface is 98% icy nitrogen. Minor traces of carbon monoxide and methane are present. The curve of apparent brightness versus time indicates the heterogeneous structure of Pluto's surface. The average density of matter on the planet is 2 g/cm 3 . Pluto's core (50 to 70% of its total volume), consisting of rocks, is surrounded by ice. It is possible - due to internal heating due to the decay of radioactive minerals - the existence of a liquid layer.
According to updated data, the equatorial diameter of the planet is 2380 km. Pluto is five times lighter in mass than the Moon. To date, five natural satellites are known. The last one - Styx - opened in 2012. The largest satellite is Charon. Not everything is so simple with him, but more on that below.
The cosmic body got its name from the ancient Greek mythical boatman who transported the souls of the dead across the waters of the Styx. Charon is the planet's satellite, the first to be discovered (D. Christie, USA, 06/22/1978). It is sometimes called Pluto 1.
The diameter of Charon is 1220 km. The mass is six times less than the mass of Pluto. The distance between the centers of cosmic bodies is 19.6 thousand km. The satellite Charon runs through its orbit in 6.4 days, which coincides with the period of revolution of the planet around its axis (a similar picture is observed for the Earth and the Moon). The average density of matter on Charon is 1.73 g/cm 3 . The surface of the satellite is covered with a layer of water ice. Spectral studies indicate the presence of ammonia hydrates, indicating geological activity on Charon today.
Charon still hides many mysteries! Whose satellite this is is clear, but is it a satellite?! The fact is that the center of mass of the Pluto-Charon system (barycenter) lies outside the planet.
Double planet?
No double planets, even dwarf ones, have yet been discovered in the Solar System. There are double asteroids. The most famous of them is Antiope (Main Belt). There are also trans-Neptunian (cubiwano) binary objects - Sila-Nunam. The only cosmic bodies in the vicinity of the Sun that can claim the status of a double planet are Pluto and Charon.
At the 26th IAU Assembly, a proposal was made to assign Charon the status of a dwarf planet. Automatically, the Pluto-Charon union would be recognized as a binary system. Then the resolution did not receive the support of the majority of forum participants, although it is possible that the issue may be reconsidered in the future.
New Horizons
In the spring of 2015, after a nine-year flight, NASA's unmanned spacecraft New Horizons began its mission. Among the main tasks is the study of the Pluto-Charon system, namely:
- surface mapping, construction of temperature diagrams;
- geological and morphological (texture and relief) surveys;
- determination of the composition of the atmosphere or its traces (object - satellite Charon).
The device approached Pluto at a minimum distance of 12.5 thousand km on July 14. The program was implemented over 9 days, during which more than 50 GB of information was sent to Earth. It took a little over a year to transfer the data. What did New Horizons reveal to us?
The alleged geological activity of Pluto has been fully confirmed. The transmitted images show that there are very few meteorite craters on the surface of the planet (compared to Charon). This indicates periodic renewal of the outer layers of the planet as a result of tectonic processes.
Pluto's atmosphere turned out to be more rarefied than scientists expected - the pressure does not exceed a hundred thousandth of the earth's. Presumably, it is in the air envelope of the planet that tholins are formed - polymerized simple hydrocarbons, and then, condensing, they fall to the surface, giving it a bright color.
Mordor and the Tolins
Charon also presented many surprises. The hemisphere facing Pluto is cut by a dense network of abysses. The depth of some exceeds 7.5 km. The entire surface is covered with a layer of dirty water ice.
The northern polar cap of the satellite is of great interest. Unlike many cosmic bodies, on Charon it is dark red. According to astronomer W. Gandhi (Lowell Observatory, USA), the color of the pole can be given by the same organic copolymers - tholins, which through complex physical and chemical processes form a thin layer on the surface.
The same area, called Mordor, was discovered on another satellite of Pluto - Nix.
Despite the fact that Pluto was transferred from the status of a full-fledged planet to dwarfs, its satellites remain faithful to it. The largest of them is Charon, almost identical in size to his “lord”.
The satellite was discovered by American astronomer J. Christie in 1978. While studying a photo of Pluto, he noticed a small elongated protrusion, which was initially mistaken for an image defect. But later it turned out that this was precisely the planet’s satellite.
At first, the new object bore an alphanumeric designation, then they began to come up with its own name. Various options were proposed, but the voice of the discoverer was decisive.
Christie suggested naming his “brainchild” in honor of the Greek mythical character Charon, who transported the souls of the dead to Hades (the underground kingdom of the dead). This name was officially recognized in 1986.
10 facts about Charon that are interesting to know
The diameter of the satellite is 1210 km (this is more than ½ the size of Pluto itself). Its mass is 1.5 * 1021 kg (approximately 11.6% of the planetary mass).
It was the discovery of Charon that allowed researchers to clarify the indicators of Pluto’s massiveness.
The planet and satellite are 19.6 thousand km away from each other. Most likely, they have a common center of gravity, since they move unusually - one after another. Their orbital period is the same and is 6.2 Earth days.
The density of the object is 1.6 g/cm3. This suggests that in its composition rocks (55%) slightly predominate over water ice (45%).
There is no nitrogen in the icy surface of Charon (unlike its planet), since the temperature of the satellite is very low, down to –220°C.
Due to its massiveness, the celestial body has an almost round shape. The surface color is gray, it does not have the reddish tint inherent in Pluto.
According to scientists, the satellite was formed from a collision with a planet. At first it shattered into pieces, then partially recovered.
Charon has no atmosphere, but there are active cryogeysers on the surface. This was shown by images taken using the Hubble telescope.
Because of their common center of mass, many scientists tend to consider Pluto and its largest moon a binary system, like the Earth and the Moon.
At the end of the 20th century, astronomers repeatedly observed eclipses of the system, which occur only twice during the entire orbital path of Pluto, which is 248 years.
In 2006, the IAU proposed recognizing Charon (along with two other satellites) as a full-fledged planet. But after fierce debate, the matter ended with Pluto being deprived of its status, and a new term appeared in the classification - a dwarf planet. Thus, bad luck for the planet and satellite turned out to be common.
Pluto's faithful satellite Charon can be found in. It will become an original talisman gift, charging with cosmic power and strength.
