Forgotten by all pluto and charon. Planet Pluto and satellite Charon
Pluto (left) and its moon Charon (photo taken with the Hubble Space Telescope).
After complex mathematical processing on a computer, based on the original image (top inset), scientists were able to build a photometric model of the surface of the planet Pluto.
The satellite telescope, named after the American astronomer Hubble, made the first observations of Pluto - the most distant (ninth in order from the Sun) of the major planets of the solar system. This tiny cold planet, moving at a distance of 40 times greater from the Sun than the Earth, for a long time remained completely unexplored.
In one of last year's articles (see "Science and Life" No. 1, 1997), we said that spacecraft were not directed to Pluto, and almost nothing could be distinguished on it using ground-based telescopes. And that now, it seems, the chance to explore the atmosphere of this planet has been lost. Because Pluto, which has a highly elongated orbit, will move away from the Sun in the next hundred years. The atmosphere of the planet will soon freeze and fall on its surface in the form of snow. Only two hundred years later, Pluto will again be at the closest distance from the Sun and will be in an advantageous position for observations from the Earth.
The existence of the planet Pluto, as is known, was first theoretically predicted by the American astronomer P. Lovell in 1915. 15 years later, the planet was discovered by an amateur astronomer K. Tombo. He found in the photographs taken by the observatory in Flagstaff (USA), an asterisk of the 15th magnitude moving among the other stars. And I realized that this is the ninth largest planet in the solar system. For several decades, it was not known that Pluto had a satellite. It was discovered almost by accident in 1978 by an American astronomer. Looking through photographic images of the planet, he noticed that in the pictures the faint star, which is obtained when photographing Pluto, looks slightly elongated. Astronomers rechecked this discovery several times and made sure that Pluto has a satellite. He was named Charon.
It was only very recently that the Hubble Space Telescope for the first time took an image where both Pluto and Charon are clearly visible.
Now we know that the diameter of Pluto is 2320 kilometers, and its satellite is 1270 kilometers. A truly unique couple. Nowhere else in the solar system is there such a planet that is only twice the size of its satellite. It would be fair to call Pluto a double planet.
After several shooting sessions with the Hubble telescope, astronomers have accumulated enough information to build the first, of course, a very approximate map of the surface of the mysterious planet. With the help of complex mathematical processing, they created a terrain model with the location of all any noticeable light and dark formations. The map is not very impressive, but if you imagine that it can be compared to trying to see something on a tennis ball, carried at a distance of 125 kilometers ...
So far, almost nothing can be said about the nature of Pluto and its satellite, except that Charon is somewhat bluer in color than Pluto. This may mean that they were not formed from a single cloud, and only then were somehow brought together by circumstances unknown to us. In order to expand our knowledge of the most distant planet in the solar system, additional observations are needed with a space telescope. We will wait for them.
Until 2006, Pluto, whose moon is Charon, was considered the ninth planet in 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.
Mystery of the ninth planet
Observation of Neptune, analysis of its orbit showed that he alone cannot have such a strong impact on the movement of the seventh planet - Uranus. In 1906, American philanthropist, amateur astronomer Percival Lowell launched the Planet X project to search for the ninth "inhabitant" of the solar system. Various combinations of circumstances (marriage in the emulsion of a photographic plate, the 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. Tombo, 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
The calculation of the exact physical parameters of the planet, due to the 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 not characteristic of the planets. During the last century, repeated attempts were 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 moon, Charon, was discovered. This made it possible to 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 in this gravitational equation? The search for "Object X" resumed again with the same zeal, but did not bring results.
To the relief of many, information returned to Earth by the unmanned Voyager 2 spacecraft in 1989, and refined calculations performed by NASA experts four years later, explained all the inconsistencies in the motion of Uranus.
ice world
Pluto can only be seen through a telescope as an object of 15th magnitude. 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 apparent brightness vs. time curve is indicative of the inhomogeneous structure of Pluto's surface. The average density of matter on the planet is 2 g/cm 3 . The core of Pluto (from 50 to 70% of the 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. In terms of mass, Pluto is five times lighter than the Moon. To date, five natural satellites are known. The last - Styx - was opened in 2012. The largest satellite is Charon. With him, not everything is so simple, but more on that below.
The cosmic body got its name from the ancient Greek mythical boatman who transported the souls of the dead through the waters of the Styx. Charon is the first satellite of the planet discovered (D. Christie, USA, 06/22/1978). It is sometimes referred to as 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 space bodies is 19.6 thousand km. The satellite Charon runs through its orbit in 6.4 days, which coincides with the period of the planet's revolution around its axis (a similar pattern 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, which is indicative of today's geological activity on Charon.
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 found in the solar system. There are double asteroids. The most famous of them is Antiope (Main Belt). There are also trans-Neptunian (kyubivano) binary objects - Force-Nunam. The only space 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 union Pluto - Charon would be recognized as a binary system. At that time, the resolution did not receive the support of the majority of the forum participants, although it is possible that the issue may be revised in the future.
New Horizons
In the spring of 2015, after a nine-year flight, NASA's New Horizons unmanned spacecraft 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).
At a minimum distance of 12.5 thousand km, the device approached Pluto on July 14. The program was implemented within 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" open to us?
Received full confirmation of the alleged geological activity of Pluto. The transmitted images show that there are very few meteorite craters on the surface of the planet (compared to Charon). This indicates the periodic renewal of the outer layers of the planet as a result of tectonic processes.
The atmosphere of Pluto 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 shell 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 tholins
Charon also presented many surprises. The hemisphere turned to 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.
Of great interest is the northern polar "cap" of the satellite. Unlike many cosmic bodies, on Charon it is dark red. According to astronomer W. Gandhi (Lowell Observatory, USA), the pole can be colored by the same organic copolymers - tholins, which form a thin layer on the surface through complex physical and chemical processes.
The same region, called Mordor, was found on another satellite of Pluto - Nikta.
Amazing in its characteristics and mysterious in origin, Pluto's satellite Charon was considered the only natural satellite of a small planet in our solar system, until 2005, when astronomers found two more celestial bodies revolving around this planet. Charon is located almost twenty thousand kilometers from the planet, its mass is 1.9 sextillion kilograms, and the radius of the planet, according to rough estimates, is 600 km.
Pluto's moon Charon
For many years since the discovery of the satellite Charon, and this is 1978, it was believed that the planet Pluto had only one single satellite. And that his discovery was due to a careful study of the images of Pluto, where the planet appeared with a slight bulge, which turned out to be its satellite passing in front of the disk of the planet. In 1985-1990, Pluto and the satellite Charon entered the eclipse phase, when their orbits, both the planet and its satellite, became visible from the Earth, as if from an edge. This is a rare phenomenon that occurs only 2 times in Pluto's 248-year revolution around the Sun, so we can say that scientists were very lucky to get into this period, which accurately established the presence of a satellite and its size.
(In the picture, the surface of Pluto and the large satellite Charon in the imagination of the artist)
The satellite, due to its remoteness from the star, has a low temperature on its surface, it is 53 degrees Kelvin, which, translated into degrees Celsius, means a mark of 220 degrees below zero. Therefore, the entire surface of the satellite is covered with water ice, this will once again make scientists think about the origin of this celestial body. There is an opinion that the satellite has geological activity, which can form liquid on the surface, scientists justify this fact by the fact that ammonia hydrates were found on the surface, which should have undergone rapid decay due to solar activity.
(In the picture Pluto and its satellite Charon in the imagination of the artist)
All data obtained by spectral analysis are reliable, but scientists promise to soon provide new parameters of the planet, because by 2015 research will be more closely involved. An interesting fact is that Pluto and Charon turn at the same time, because of this they are always directed to each other by one side.
Small moons of Pluto
The Pluto-Charon system turned out to have smaller brothers and sisters. These are two small satellites, S/2005 P1 "Hydra" and S/2005 P2 "Nikta", discovered in 2005, their diameter is not more than 45 - 60 km. Then, in 2011, the fourth P4 satellite with a diameter of 13-34 km was discovered, and a year later, the fifth smallest P5 satellite, whose diameter is only 10-25 km, was added to the family of known Pluto satellites.
(The image taken by the Hubble Space Telescope on July 7, 2012 shows the five moons of Pluto, two of which P4 and P5 are likely to be named Vulcan and Cerberus, which received the highest number of votes in the SETI internet voting)
Thus, at present, for 2013, exactly 5 satellites of the planet are known, the last 2 of which will soon receive their names p4, most likely - "name", and P5 - "" according to information ... (source)
Origin of Pluto's moons
(On 3D modeling, a view from the surface of Pluto, the satellite Charon and its younger sister are clearly visible, most likely the Hydra satellite in the artist's imagination, and a bright star is seen far, far away - this is the Sun)
The Pluto-Charon system is called so because, by studying very different properties and planets, scientists hypothesized that both objects of the Solar System appeared during a collision during the independent formation of the planet Pluto and its future satellite, that is, the Charon satellite was formed from fragments of the planet. By the way, two other satellites of Pluto, Nikta and Hydra, may have formed from the same fragments. But the origin of other small satellites of Pluto is still a mystery, since it is not clear how such small objects can be so close to a fairly large Charon, despite the fact that their circular orbit rejects the assumption that they are captured by Pluto's gravity.
Scientists believe that if Pluto still has satellites, then their diameter will be no more than 20 km and their appearance is more likely associated with a collision in the distant past, which also does not exclude the possibility of Pluto having rings from the same fragments.
In the solar system there are planets so small that they are called dwarfs. Pluto is one of these. But even small planets have satellites. Its largest satellite is Charon. But he is not the only one of his kind. There are others. Of course, they are not so great, 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 other, smaller satellites.
Planet Pluto
Until 2006, Pluto stood on a par with the main planets of the solar system and was a full-fledged unit.
Now it has been given the name of a dwarf planet, after which it was believed that it is the largest object in the dark disk-shaped zone.
One day, scientists realized that Pluto is not a unique object of its environment, which are all the other planets located in the solar system. And that more than one such object can be found if we explore the space beyond the orbit belonging to Neptune. And soon a certain body, called Eris, was indeed discovered. It was which can be compared with Pluto. After this discovery, it became clear that in the world, in fact, there is no definition of a planet. And in 2006, a definition was approved that includes three positions. According to him, those that correspond to only two of the three positions are called. Pluto belongs to those.
It got its name from an eleven-year-old girl who decided that the name of the god of the underworld would be suitable for a distant, probably cold and dark planet, and told her grandfather about it. And already the grandfather conveyed the wish of his granddaughter to the observatory, where he was finally approved.
In 2006, a spacecraft called New Horizons was launched to the planet Pluto. It was the month of January. This apparatus flew up to the planet at a distance of twelve thousand kilometers and accumulated a large 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.
Planet Features
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.
From the Earth and the satellite Charon, like other small satellites, are removed quite far. Therefore, they are not well studied. There is an assumption that the surface of this planet has a base of rocky composition, which is covered with water ice, as well as 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 the shape of a circle, Pluto can either get very close to the Sun, or, conversely, move away at a great distance. In the process of its approach, the formation of an atmosphere around the planet, which consists of methane and nitrogen, also occurs. 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 is due to the fact that the glaciers freeze again.
Satellites of Pluto. Charon and small satellites of the planet
Pluto has five natural satellites. The largest moon of Charon was discovered in 1978. Two smaller moons, named Nix and Hydra, were seen in 2005.
Kerberos was next. It was discovered by the Hubble telescope in 2011. And finally, in 2012, scientists discovered the presence of a fifth satellite in Pluto, which was named Styx. All the names of the satellites in one way or another refer to the underworld kingdom 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 Ancient Greece. It was discovered by US astrophysicist James Christie. It happened at the Naval Observatory in 1978.
This satellite is very large. Its size equates to half the size of Pluto itself. The distance separating it from the planet it accompanies is almost twenty thousand kilometers. It's about the same as from London to Sydney.
Charon is a satellite of Pluto, which many scientists have come to consider a minor component of the binary system of planets. It was even given the name Pluto-1. The rotation periods of Pluto and Charon are the same. Due to this phenomenon, they are always turned to each other by the same side. This phenomenon even got its name - tidal lock.
The surface and composition of the satellite
The moon Charon differs in 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 below zero by 220 degrees Celsius. But also the reason for this composition is the fact that Charon is not so massive as to hold 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 were in orbit. Also, many scientists believe that Charon is connected.
Satellite of Nikta
Charon is the largest, but there are others. One of them is Nikta. The discovery of this satellite was made public in 2005, on October 31. He owes his name to the goddess of eternal night.
The orbit in which the satellite is located is circular. There is no information about the exact dimensions of Nyx yet, but it is presumably smaller than the Hydra. This is indicated by the darker color of the surface.
Hydra
If you carefully consider the existing images, you can see that Hydra is located in the same plane as the Charon satellite. The distance between Pluto and Hydra is approximately 65,000 kilometers. There is no information about the exact dimensions of this satellite. Scientists only assume that the value of its diameter is in the range from 52 to 160 kilometers.
Hydra's surface is brighter than Nix's. Approximately 25%. This suggests that its reflectivity is higher, which means that the dimensions are larger. The satellite got its name in honor of the monster from Greek mythology, which has a hundred heads.
Kerberos and Styx
The fourth satellite of Pluto is called Kerberos, also received in honor of 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 along which the fourth satellite rotates is located between the orbits of Nix and Hydra. Produces an revolution around the planet in thirty-one days.
The fifth satellite of Styx has the smallest size. Presumably the value of its diameter is between 10 and 25 kilometers. This satellite rotates in an orbit located between the orbits of Charon and Nikta. Its resonance with Charon is a ratio of one to three. It owes its name to the river, which in the myths of Ancient Greece separates two worlds - the living and the dead. It was also discovered thanks to the Hubble in June 2012.
Many issues have been covered in this article. We learned which planet Charon is a satellite of, what are its features, sizes and composition. Now to the question: "Charon is a satellite of which planet?" - you confidently answer: "Pluto". By the way, one of the theories of the emergence of satellites around Pluto suggests that they were all formed as a result of the collision of this planet with some large object from the Kuiper belt. Unfortunately, to date, almost nothing more can be learned about these amazing objects. After all, Pluto is not only too far from the Earth, but also does not have a very good reflectivity.
