Why is Pluto not part of the Sun s 9 planets right now?

After Pluto was discovered. Astronomers seem to have found a brother. Gleefully make it the ninth largest planet in the solar system.

But later, with the development of science and technology, after learning more and more about it, I found that it was much smaller than I originally thought. And it has been calculated that its orbit will be within the orbit of Neptune. This violates people's accepted standards for large planets.

Since then, the debate over whether Pluto is a big planet has begun. And the immediate cause of this is the discovery of another planet larger than it outside Pluto - Xena. In this way, astronomers believe that there may be countless such "large planets" in the Kuiper Belt where Pluto and Xena are located.

That's when the debate about Pluto heats up. Astronomers are faced with the choice of either expelling Pluto from the ranks of the great planets; Either accept Xena as the "tenth planet". And the trouble with accepting Xena is that there may be hundreds or thousands of "big planets" behind her!

In this way, astronomers around the world debated and finally adopted a new definition of the planet at the International Astronomical Union Congress in August 2006. A large planet must meet three conditions:

1. The celestial body should revolve around the star;

2. With a large enough mass, it must be able to rely on its own gravity and make its own shape reach an approximate spherical shape through hydrostatic equilibrium;

3. The object plays a dominant role in the orbital region and is not disturbed by adjacent objects in orbit.

Pluto conforms to the first 2 but not to the 3rd. Its orbital region crosses the orbit of Neptune and is visibly disturbed by it. So it can't be considered a big planet.

By the new definition, it is called a "dwarf planet". In fact, this third is "tailor-made" for Pluto. The goal is to kick it out of the ranks of the great planets.

A planet must meet three conditions: it must be the largest object in the region; It must have a large enough mass to be able to rely on its own gravity to achieve an approximate spherical shape through hydrostatic equilibrium; Nuclear fusion reactions cannot occur inside celestial bodies. According to this scheme, in the solar system, only eight celestial bodies in the solar system, including Venus, Saturn, Jupiter, Mercury, Earth, Mars, Uranus, and Neptune, are confirmed as large planets, and Pluto is not among the large planets.

Because Pluto is just a dwarf planet, it doesn't fit the characteristics. To put it simply, it doesn't have satellites.

Now Pluto has been relegated to a dwarf planet.

Early geography textbooks had nine planets in the solar system.

Now there are only eight planets

It's too small, and there are many planets about the same size that have been found around it, if it's counted as nine planets, then I won't do it later when I find it haha.

Due to being attracted away from the solar system by a planet in the extragalactic galaxy, he was removed from the Astronomical Society a few years ago, and it is not known that he was attracted to that planet.

The eight planets Pluto is now a dwarf planet although there are still calls for Pluto to be restored to its status.

Strictly speaking, there are eight planets. Pluto has been removed from the ranks of large planets and is now called a dwarf planet, which is a category between large planets and small planets, which cannot be considered big or small, but of course it still belongs to the solar system. There are also eight planets, namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

From the distance from the Sun from the smallest to the largest, it is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. In order of size, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, and Mercury are listed in order. In order of mass, Jupiter, Saturn, Neptune, Uranus, Earth, Venus, Mars, and Mercury are ranked by mass.

There are eight planets.

It is no longer part of the solar system.

There are also Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Pluto has been relegated to a dwarf planet because the criteria for being a planet are: it has a certain orbit and can clear small objects from its orbit.

Pluto has been relegated to a dwarf planet and is no longer a planet of the original solar system, and now has eight planets.

A planet is a planet because it is the dominant gravitational body in this orbit (other objects in and around the planet's orbit should be centered on the planet), but Pluto does not meet this criterion, there are many Pluto-like objects in and around Pluto's orbit, and the mass is not much different from Pluto's. Pluto is only twice as massive as the other objects in its orbit. If Pluto can be considered a planet, then other celestial bodies inside and outside this orbit should also qualify.

Pluto, as the smallest and farthest planet from the Sun, travels comfortably in its orbit, and everything is fine for Pluto. But with advances in science and technology, scientists have discovered other Pluto-like objects, which are also made up of ice and rock.

This creates problems for Pluto, as it is tantamount to treating Pluto as part of a large ensemble of scattered Kuiper Belt objects (most of which are made up of rock and ice). The Kuiper Belt extends about 55 astronomical units (55 times the distance between the Sun and Earth) from Neptune's orbit, and astronomers estimate that there are about 70,000 Pluto-like objects in the Kuiper Belt. <>

Obviously, Pluto has no motivation to mix up in the solar system at all, and being expelled is a normal thing. Just because Pluto is removed from the planetary ranks does not mean that it can still exist as a planet. There is still a reason why Pluto is not represented by the ranks of the eight planets, and there is nothing else in Pluto's orbit except the presence of Pluto, and such an orbit is also found in dwarf planets.

For example, the dwarf planets SeDNA and 2012VP113 have no other celestial bodies in their orbits.

Pluto Null does not conform to the third law of planets, it does not have enough gravity to clear the small objects next to it, and it is not very large. And there is a dwarf planet named "Xena" that is larger than Pluto, which is also a very important reason why Pluto is devalued <>

Scientists have made it clear that Pluto's return to the planetary family is impossible, because Pluto is not a planet at all. Therefore, we all have to get used to changing the nine planets of the solar system to eight planets in the future!

Because the number of moons around Pluto is not up to the required number, and Pluto is not a regular spherical shape, but an oval.

In 2006, the International Astronomical Union (IAU) adopted a scientific definition of planetary standards. Contents include:1

It has a large enough mass that its gravity allows itself to maintain mechanical equilibrium in the static dispersion of the fluid: if it does not rotate, it is spherical; If rotated, it is ellipsoidal. 2.

Orbiting the Sun and not other celestial bodies. 3.Able to empty its own orbit, there are no other objects with relatively high mass within the same orbital distance.

According to this definition, the number of planets in the solar system is officially reduced to 8, and Pluto is no longer a wild bent planet in the solar system.

He is too small, his mass is only two-thousandths that of Earth, and there are too many planets like him in his orbit.

Because scientists discovered another planet that was bigger than it, Xena, and then Pluto was kicked out because it was far behind.

Because Pluto is downgraded, it will only be called a "dwarf planet" along with some other "siblings" of about the same size.

The term "planet" originated from the Greek word for "wanderer" in the solar system. For nearly a thousand years, Mercury, Venus, Earth, Mars, Jupiter, and Saturn have been considered the standard planets in the solar system. After the 19th century, astronomers discovered Uranus, Neptune and Pluto one after another, making the "planets" of the solar system nine in number.

Since then, the "Nine Planets" have become a household name.

However, new astronomical discoveries continue to call into question the traditional notion of the "Nine Planets".

According to the new definition adopted by the International Astronomical Union Conference, a "planet" is a celestial body orbiting the Sun, whose gravitational pull is sufficient to overcome its rigid physical strength to make the celestial body spherical, and capable of clearing other objects in the vicinity of its orbit. According to the new definition, the planets of the solar system will include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, all of which were discovered and buried before 1900.

According to the new definition, a celestial body that also has sufficient mass and is spherical in shape, but cannot clear other objects in the vicinity of its orbit is called a "dwarf planet". Pluto is a dwarf planet. Other objects orbiting the Sun that do not meet the above conditions are collectively referred to as "small bodies of the solar system". Liquid-free.