Why was Pluto, one of the nine planets, kicked out of the list of planets?

The reason for this controversy and the end result is that astronomy is constantly evolving, and the planets that are close to Pluto within the range of Pluto's orbit are constantly evolving. And, according to **, there will be hundreds more such planets. In order to avoid the embarrassment of the "ten planets" and "eleven planets" constantly appearing, some people advocate that the "nine planets" are just historical terms.

revolving around the sun; It has enough mass to overcome the solid stresses to form a shape that is in static equilibrium of the fluid (close to the sphere). Emptied other celestial bodies in orbit.

Pluto does not meet the second and third conditions. Because Pluto is small in both mass and volume. Pluto is only one-sixth the mass of the Moon and one-third the volume of the Moon.

Because Pluto's orbit intersects Neptune's, Neptune cannot be a planet if you think of Pluto as a planet. Pluto was removed due to disagreement. Pluto as the ninth large planet, Clyde Tobo discovered, in fact, before that, astronomers also predicted the existence of a ninth large planet in addition to Neptune, but it has never been discovered.

Clyde Tombaugh compares starlight taken at different times** to find moving objects. Generally speaking, celestial bodies that move significantly in a short period of time are those that are very close to us. At least there are comets, asteroids, etc. in the solar system.

When Pluto was first discovered, the astronomical community was very excited, thinking that the level of human observation was limited and that Pluto and the eight known planets should be similar, so Pluto no longer thought about it and became the ninth planet. In fact, it is a foreshadowing of Pluto being driven out of the ranks of the big planets. Especially with the improvement of observation technology, scientists have discovered more celestial objects outside Neptune, proving that Pluto is not the only one, and Pluto's status is increasingly doubted.

The distance between Pluto and the Sun averages 40 astronomical units, or 40 days. Very little solar radiation energy is received, and the temperature on Pluto's surface can drop to minus 230 degrees. What is this concept?

If the Earth is at such a temperature, then eventually the Earth's atmosphere will turn into "ice crystals" and fall to the ground like snow.

Pluto was originally the smallest of the nine planets in the solar system, with only the mass of the Earth, but it is the largest known object in the Kuiper Belt at the edge of the solar system, with its rotation in the opposite direction to the Earth. This means that the Sun rises westward from Pluto.

Because Pluto is relatively small, it does not meet the volume and mass requirements of the eight planets, and it does not meet the standards of the eight planets, so it is eliminated.

Because Pluto's orbit is not the same as that of other planets, it is not in a plane, and Pluto's mass is so small that it does not meet the criteria of a planet.

Because its mass has been surpassed by other planets, and other stars have overtaken it and taken its place, making it a thing of the past.

The reason Pluto was kicked out of the Nine Planets was because on August 24, 2006, the International Astronomical Union (IAU) passed a decision to redefine the definition of "planet", according to which Pluto is no longer considered a planet.

According to the new definition, the following three conditions must be met:

1.It must revolve around the sun;

2.It must be large enough to become a geometrically balanced body under the action of its own gravity, not an asteroid;

3.It must have been cleared of other objects in its orbit, meaning that no other relatively large objects exist near its orbit.

According to the third condition, Pluto is no longer considered a planet because it shares orbit with other asteroids, dwarf planets, and celestial bodies. Conversely, Pluto is classified as a "dwarf planet," meaning that it is a smaller shed of objects in the solar system and, like other dwarf planets and bodies, does not meet the definition of a "planet."