What constellation is 1978520 _ 19780520?

Pluto

The following information refers to the original Pluto, which has no name. Define the asteroid serial number: 134340.

According to the resolution of the General Assembly of the International Astronomical Union on August 24, 2006, Pluto is regarded as a "dwarf planet" in the solar system and is no longer regarded as a planet. There are seven satellites larger than Pluto in the solar system (Moon, Io, Europa, Ganymede, Callisto, Titan and Triton).

Orbit: The average distance from the sun is 59 13520000 km (39.5 astronomical units).

Diameter: 2274 km

Mass: 1.27e22

In Roman mythology, Pluto (Greek called Pluto) was the leader of the underworld. The planet got this name (rather than other suggestions) because it was too far away from the sun and kept silent in endless darkness. Coincidentally, the first two letters of Pluto are the discoverer percival Lowell, which is an abbreviation.

Pluto was discovered by a lucky coincidence in 1930. A calculation "conclusion" that was later found to be wrong: based on the study of the operation of Uranus and Neptune, there is another planet behind Neptune. Clyde W. Tombaugh of Lowell Observatory in Arizona, USA, made a very careful observation of the solar system because he didn't know this calculation error. However, because of this, Pluto was discovered.

After Pluto was discovered, people soon found that Pluto was too small and its orbit was different from that of other planets. The research on the unknown planet (Planet X) continues, but nothing has been found. If the mass of Neptune calculated by Voyager 2 spacecraft is adopted, another mass difference will disappear and there will be no tenth planet.

Pluto is the only planet that has not been visited by a spaceship. Even the Hubble Space Telescope can only observe its surface.

Fortunately, Pluto has a moon, Phobos. It's also lucky to be found. This was discovered in 1978, when it was running into the solar system, just at the edge of its orbit. So it is possible to observe a lot of Pluto's motion through Pluto, and vice versa. By accurately calculating what objects are covered and when, and observing the bright curves, astronomers can draw a rough map of the bright and dark areas of the two hemispheres.

The radius of Pluto is still unknown. The value of JPL (Jet Propulsion Laboratory) 1 137 km is considered to have an error of 8, almost 1%.

Although the total mass of Pluto and Phobos is clearly known (it can be determined by accurately measuring the period and radius of Phobos orbit and Kepler's third law), it is difficult to determine the respective mass of Pluto and Phobos. This is because it is necessary to measure the center of mass of Pluto and Pluto-1 system more accurately to calculate the mass alone, but they are too small and far away from us, and even the Hubble Space Telescope can't do anything about it. The mass ratio of these two stars may be between 0.084 and 0. 157. More observations are going on, but only one spaceship can be sent there to get really accurate data.

Pluto is the second celestial body with great contrast in the solar system (second only to Partos). Exploring the reasons for these differences is one of the main goals of the planned Pluto Express.

Pluto's orbit is very abnormal, and sometimes it is closer to the sun than Neptune (starting from 1979, 1 and continuing to 1999).

The common motion ratio of Pluto and Neptune is 3:2, that is, the period of revolution of Pluto is exactly 1.5 times that of Neptune. Its orbital intersection angle is also far from other planets. So although Pluto's orbit seems to cross Neptune's orbit, it doesn't. So they will never collide (explained in great detail here)

Like Uranus, Pluto's equatorial plane is almost at right angles to its orbital plane.

The surface temperature of Pluto is not very clear, but it is about 35 to 45K(-238 to -228℃).

The composition of Pluto is unknown, but its density (about 2g/cm3) indicates that Pluto may be composed of 70% rocks and 30% ice water like Triton. Bright parts of the earth's surface may be covered with some solid nitrogen and a small amount of solid methane and carbon monoxide. The composition of the dark part of Pluto's surface is unknown, but it may be a photochemical reaction caused by some basic organic substances or cosmic rays.

Little is known about Pluto's atmosphere, but it may be mainly composed of nitrogen and a small amount of carbon monoxide and methane. The atmosphere is extremely thin, and the ground pressure is only a few micro-pa. Pluto's atmosphere may only be gas when Pluto is near perihelion; In the remaining years of Pluto, gases in the atmosphere condensed into solids. Near perihelion, part of the atmosphere may escape into the universe, and may even be attracted to Phobos. The planners of the Pluto Express mission hope to reach Pluto when the atmosphere slides and freezes.

Pluto and Triton have unusual orbits and similar volumes, which makes people feel that there is a historical origin between them. It was once thought that Pluto was once a satellite of Neptune, but now it is not. A more general theory holds that Triton, like Pluto, was originally in an independent orbit around the sun and was later attracted by Neptune. Triton, Pluto and Phobos may be members of a large class of similar celestial bodies, while others are excluded from the Oort Oort Cloud (matter outside the Kuiper Belt). Pluto may be the product of a collision between Pluto and another celestial body, just like the earth and the moon.

Non-professional telescopes can also observe Pluto, but it is not easy. Mike Harvey's planet sky map can show the nearest position of Pluto (and other planets) in the sky, but it takes more detailed sky map and months of careful observation to really find Pluto. Planetary programs such as "Splendid Galaxy" can draw accurate sky maps.

On August 24, 2006, the planet was discussed at the Prague meeting, excluded from the ranks of the nine major planets and officially downgraded to a dwarf planet.

Debate on Pluto's planetary qualification

When Pluto was first discovered, it was considered several times the size of the earth. Soon, Pluto was also written into textbooks as the ninth largest planet in the solar system. However, with the passage of time and the continuous upgrading of astronomical observation instruments, people increasingly found that the estimation at that time was a major "mistake" because its volume was much smaller than the original estimation. In addition, Pluto's planetary status has always been the focus of debate among astronomers because there has never been a specific and clear definition of a planet. Especially since the first discovery of the Kuiper Belt in 1992, more astronomical discoveries have intensified the debate on planetary qualifications.

This new discovery rekindled the debate.

2 1 century, the improvement of astronomical telescope technology has made people have a deeper understanding of Neptune celestial bodies. In 2002, an asteroid named 50000 Quaoar was discovered. The diameter of this newly discovered asteroid (1280 km) is more than half that of Pluto. In 2004, the asteroid named 90377 Sedna had a maximum diameter of 1800 km, while Pluto had a diameter of only 2320 km.

On July 9, 2005, another newly discovered celestial body besides Neptune was officially named Eris. According to its brightness and albedo, Eris is slightly larger than Pluto. This is the largest celestial body found in the solar system after the discovery of Neptune in 1846. Although there was no official consensus at first, its discoverer and many media initially called it "the tenth largest planet". Some astronomers believe that the discovery of Eris provides strong evidence for rethinking Pluto's planetary status.

Even the salient features of Pluto-its satellites and atmosphere-are not unique. Some asteroids in Neptune's outer celestial belt also have their own moons. In addition, the spectral analysis of Eris shows that it has a surface similar to Pluto, and Eris also has a larger satellite, Mia, Snoww.

Resolution of the International Astronomical Union (IAU)-"Star Registration" for expelling Pluto

According to the resolution adopted by the International Astronomical Union on August 24, 2006, celestial bodies called planets must meet three main conditions.

1. This celestial body must be in orbit around the sun.

2. The celestial body must have enough mass to overcome the solid stress, so as to achieve the shape of hydrostatic balance (approximately spherical).

The celestial body must have cleared the area near its orbit.

Pluto, on the other hand, does not meet the third planetary standard mentioned above.

The International Astronomical Union further decided that Pluto should be classified as a dwarf planet and can be used as the prototype of an unnamed celestial body other than Neptune. Before this resolution, people also put forward different planetary schemes. Some even mentioned that besides Pluto, Mercury should be disqualified from being a planet on the earth, while others suggested that some asteroids should also be included in the planet list.

"New Vision" was launched in June 2006 at 5438+ 10, and it is expected to reach Pluto for observation at 438+05 in 2065.

Of the nine planets, Pluto is the farthest from the sun and has the smallest mass. It hobbles in the cold and dark space 5.9 billion kilometers away from the sun, which is very similar to proto, the god of the underworld in Roman mythology. So people call it Pluto, which is the first two letters of the English name of Pluto in astronomy, and the abbreviation of the name of Lovel, an American astronomer who promoted the discovery of Pluto.

Pluto is the latest planet to be discovered. Compared with the discovery of Uranus and Neptune, the discovery of Pluto is "a lot of trouble". Pluto's brightness is very weak, only 15 and so on. Even in the photos taken by large telescopes, it is no different from ordinary stars. Finding it among thousands of stars is like looking for a needle in a haystack.

In the process of searching for Pluto, Lovel, an American astronomer who is an astronomy enthusiast, calculated the position of this unknown planet in detail and searched it carefully with a telescope, which took more than ten years. Until19161.0616 suddenly died.

1925, Lovel's brother donated a large-field photographic telescope with a diameter of 32.5 cm, which provided excellent conditions for continuing the search for new planets. From 65438 to 0929, the director of Lovel Observatory invited clyde william tombaugh to join the search for unknown planets. They searched one by one, photographed a large number of negatives, and examined each one carefully. This job is hard and boring. 193065438+1October 2 1 day, Tang Bo finally found this new planet in the negative of Gemini.

Mass: 0.0024 Earth mass

Radius:1350km

Period: 90465 days

Half-length diameter of orbit: 39.87 astronomical units.

Track eccentricity: 0.256

Orbit inclination: 17. 1.

Strange footprints

Pluto was once considered as a planet outside Neptune's orbit at the beginning of its discovery, but it turns out that it is not. For example, from1979 65438+1October 2 1 to 65438+March 0999 14, Pluto is closer to the sun than Neptune. This is because Pluto's orbital eccentricity and inclination to the ecliptic plane are greater than those of other planets. Pluto is closer to the sun than Neptune at perihelion, and Neptune becomes the farthest planet from the sun. Every once in a while, Pluto and Neptune will approach each other, and the orbits of the two planets will cross on the ecliptic projection map. But there is no need to worry about their collision, because their orbital planes do not coincide, and even near the intersection, the distance between them is still very large. They will fly by like vehicles driving at a fork in the road.

The appearance of satellites

1In July, 978, Christie of the U.S. Naval Observatory, while studying photos of Pluto, happened to find that Pluto's small round surface was slightly elongated. He found all the photos of Pluto since 1970, and found that this phenomenon appeared regularly, so he concluded that Pluto has satellites. Because Pluto is too far away from us, it is impossible to separate Pluto from its satellite in a large telescope. It's like an anemometer at a weather station. The crossbar connects two balls and rotates in the high wind. From a distance, when two spheres are combined into one, only the changes of its time circle and time plane can be detected. Pluto's moon is named Ka Rong. In Greek mythology, Chalong was a serviceman in prout, who devoted himself to crossing the dead in the ghost sea. Chalong period of revolution and Pluto have the same rotation period, which is 6.39 days.

What is the diameter of the ghost king star?

Because Pluto is too dark and too small, it is impossible to determine its size for a long time after its discovery. At first, it was estimated that its diameter was 6600 kilometers, and it was changed from 1949 to 10000 kilometers. 1950, kuiper revised it to 6,000 kilometers with a newly-built 5-meter telescope, 1965, and limited the diameter to 5,500 kilometers by using Pluto to cover the stars. 1977 It was found that the surface of Pluto was frozen methane. According to its albedo, the diameter of Pluto is reduced to 2700 meters. 1980, the 3.6m infrared telescope on Monaque Mountain measured Pluto's diameter at 2600-4000km and Chalong's diameter at 2000km. In recent years, some astronomers have observed that the diameter of Pluto is about 2,400 kilometers, which is smaller than the diameter of the moon (3,475 kilometers), while the diameter of Chalong is 1 180 kilometers, which is the largest ratio of planets to satellites among the nine planets. So some people say that Pluto and its satellites are more like a two-planet system.

An unknown number of planets

Pluto has only been discovered for more than 60 years, plus it is small and far away, which is the most unknown one in the planet at present. The 1970s and 1980s were the golden ages of space exploration in the solar system. Eight of the nine planets have been approached by interplanetary probes, and only Pluto is a blind spot where spacecraft have not set foot. In the list of planetary parameters given by various astronomical books and periodicals, Pluto leaves the most blank. Even if the data are listed, many of them are marked with question marks, indicating inaccuracy.

In addition to a series of unknowns, people also have questions about Pluto's identity. Pluto has the smallest diameter and mass among planets, with a density of 0.8 ~ 2.1g per cubic centimeter and an albedo of 50% ~ 60%, which is very similar to several large satellites of other planets. Is a ghost satellite a planet or a satellite? Or a big asteroid? However, whatever it is, as a celestial body on the distant boundary of the solar system, its mystery has great attraction to astronomers. I believe that in the near future, with the development of exploration technology, Pluto will become a hot topic in planetary astronomy.

Are there any alien stars?

When Copernicus proposed Heliocentrism, Saturn was the boundary of the solar system. Later, with the discovery of Uranus, Neptune and Pluto, the boundaries of the solar system extended again and again. However, in theory, the solar system should be 100 times or even 10,000 times larger than the nine planets. Are there any extra-terrestrial planets in the solar system? In this regard, astronomers have done very extensive and arduous work. During the 14 years after the discovery of Pluto, Tobo has been looking for extraterrestrial planets by looking for Pluto. He carefully examined 362 pairs of negatives with a flash comparator (these negatives account for about 70% of the whole day), looking for possible new planets from each negative. He discovered many new celestial bodies, but there were no extraterrestrial planets. Scientists believe that if there is an extraterrestrial planet, it will inevitably disturb the detector flying near it, and its influence can be reflected in the orbit of the detector. However, after flying over the orbits of Neptune and Pluto, the Voyager probe operated normally and did not provide any clues to prove the existence of unknown objects. Whether there are extraterrestrial planets is still a mystery to be solved.

5.9 billion kilometers from the earth