What was Project Pluto?

Pluto (asteroid serial number: 134340 Pluto ; astronomical code: , Unicode code: U + 2647) is a dwarf planet in the Kuiper belt. Pluto was the first Kuiper Belt object to be discovered. Pluto is the dwarf planet with the largest volume and the second-largest mass known in the solar system. Of the celestial bodies orbiting directly around the Sun, Pluto ranks ninth in volume and tenth in mass. Pluto is the largest overseas celestial body, and its mass is second only to Pluto in a discrete disk. Like other Kuiper Belt objects, Pluto is mainly composed of rocks and ice. Pluto is relatively small, only one sixth of the moon's mass and one third of the moon's volume. Pluto's orbital eccentricity and inclination are relatively high, with perihelion points of 30 astronomical units (4.4 billion kilometers) and distant points of 49 astronomical units (7.4 billion kilometers). Pluto therefore periodically enters the inside of Neptune's orbit. Neptune and Pluto do not collide due to mutual orbital resonance. It takes 5.5 hours for Pluto to reach Pluto on average.

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Since its discovery in 1930, Pluto has long been included in the nine planets of the solar system. However, since 2000, new celestial bodies have been continuously discovered in the Kuiper belt on the edge of the solar system and outside of Neptune, and their size is getting larger and larger, especially the planet Pluto discovered in 2005, which was considered to be larger than Pluto at that time, because it was estimated at that time Pluto is only about 2,300 kilometers in diameter.

But scientists have made it clear that returning to the planetary family is impossible, because Pluto is not a planet at all. So what's so special about Pluto, and why was it removed?

1. Pluto is very small: Many people think that Pluto is very small, just like ordinary asteroids. In fact, this dwarf planet has a diameter of 2360 kilometers, which is two thirds of the diameter of the moon and three quarters of the diameter of Europa. Pluto's largest moon, Pluto, is about 1207 kilometers in diameter.

2. Pluto used to be Neptune's "satellite": In 1965, researchers discovered an orbital resonance-there is an optimal gravitational point in the orbit between Pluto and Neptune. This orbital resonance prevents two planets from getting too close to each other.

1930, American astronomer

Pluto low-temperature volcano exposure

Detector captures suspected Pluto giant low-temperature volcano

On January 17, 2016, NASA said that the New Horizons space probe captured high-resolution images of one of two low-temperature volcanoes that may exist on Pluto.

In July 2015, the probe was taken from a distance of 48,000 kilometers from Pluto. The height of the suspected low-temperature volcano was 4,000 meters and the diameter reached 150 kilometers.

"Snow Mountain" found on Pluto

On March 4, 2016, the tops of some high mountains on Pluto were like the earth, and they were covered with snow. This was the latest discovery of the NASA New Horizons probe project team.

Researchers have discovered that in the dark area informally named "Cthulhu" on Pluto, there is a mountain range of about 420 kilometers long, and the top of the mountain is covered by "exotic snow and ice".
Scientists believe that the main component of these snow and ice is methane in Pluto's atmosphere, which condenses and falls to the top of the mountain. New Horizons team scientist John Stansbury said in a statement that the substance only covers the top of mountain peaks, which means that methane, like water in the Earth s atmosphere, will condense at high latitudes to " Snow and ice. "

Clouds in Pluto

According to the British Daily Mail, the NASA New Horizons probe reached Pluto for the first time in 2005. In July 2015, the probe was again close to Pluto's orbit. New Horizons probes have sent images of Pluto's icebergs, ice blocks, craters, and even snow. Recently, the latest pictures show evidence of the presence of clouds in Pluto.

This research raises the question-Should Pluto return to planetary status? But physicists say this is unlikely. According to John Spencer of the Southwest Research Institute in Colorado, the clouds appear to "stand out" from Pluto's surface.

There is a very bright low-altitude smoke over the southeast of the Sputnik Plain on the left side of the picture. There is a discrete fuzzy cloud on the sunlit surface of the Krun Macula area on the right side of the picture, but the New Horizons research team cannot confirm the true existence of the cloud. Published by Johns Hopkins University Applied Physics Laboratory

Clouds can be seen above Pluto

In other words, the research team believes that this is evidence of the existence of Pluto's atmosphere, including complex haze, and scientists continue to analyze and discuss input data as part of the normative scientific process.

If Pluto has clouds, it means that it has an active cycle, such as the Earth's water cycle or the Titan methane cycle. This research raises new questions about the surface and atmosphere of Pluto. Professor Martin Barstow, president of the Royal Astronomical Society, said: "This is an exciting new discovery when the New Horizons probe flies over Pluto, although I Think it takes some time to understand what we observe. "

Compared to Earth, Pluto's atmosphere is thinner, so there is greater uncertainty as to whether there are clouds. Barstow said: "The earth s atmospheric clouds are formed by suspended water droplets in the atmosphere. We may see a similar effect, but not necessarily water, especially when the temperature is very low, or the surface releases substances to form clouds. There is more gas in the area and it looks more opaque than the surrounding area. "

But physicists stress that even if Pluto has some type of active cycle, it won't restore planetary identity. It is reported that in 2006, Pluto lost its planetary identity. ^[10] Barstow pointed out that other planets in the solar system also have active cycles, such as Titan (Saturn's largest moon), and I don't think this latest research will be strong evidence to restore the identity of Pluto planet. ^[11]

Top 10 scientific discoveries of Pluto and its satellite system

1. The complexity of Pluto and its satellite systems far exceeds what astronomers had previously predicted.

2. The intensity of Pluto's surface activity and the new age of the geological formations in some areas have shocked scientists.

3. Pluto's atmospheric structure is lower and more hazy than expected, and its escape ratio is different from previous models.

4. There are obvious extension geological structures in the equatorial area of Charon, indicating that in ancient times, there may have been ice oceans. Other evidence returned by New Horizons suggests the possibility of an internal ocean beneath Pluto's surface.

5. Among the satellites of Pluto, those that can be age-determined by craters were born at the same time, which validated the scientists' assumption: these satellites were in a violent collision between Pluto and another Kuiper Belt object in ancient times. Forming.

6. Charon has a dark red north pole, which has never appeared in other known celestial bodies in the solar system. Scientists speculate that this was formed by the re-aggregation of atmospheric matter that escaped from Pluto on the surface of Charon.

7. The Sponic Plain, where "Heart of Pluto" is located, is formed by the strong convection of nitrogen ice, with a width of 1,000 kilometers, which is also the largest known glacial structure in the solar system.

8. "New Horizons" evidence shows that there is a huge pressure difference in Pluto's atmosphere, which means that there may have been liquid volatilization on the surface of Pluto. We only have a few solar system planets on Earth, Mars, and Titan This phenomenon was observed on.

9. The visit of New Horizons greatly enriched scientists' knowledge of several other small moons of Pluto.

10. Pluto's atmosphere is blue.

"It's unbelievable that we knew so little about Pluto's system just a year ago," said He Weaver, a mission scientist at New Horizons. "Today, however, we realize that Pluto is so special. , It overthrows our previous ideas. More exciting is that it continues to surprise us with discoveries. " ^[1]