Why is Pluto no longer in the parade of planets in our solar system

(ORDO NEWS) — Remember how in school years at the lesson of natural history we crammed the names of 9 planets of the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and baby Pluto.

Yes, yes, in those years, Pluto was considered the most real planet. What did Pluto do in 2006 that he was kicked out of the friendly family of planets in our solar system?

Let’s start with a small but fascinating backstory

Back in 1801, astronomer Giuseppe Piazzi with a group of astronomers who called themselves the “celestial police” found a completely new planet between the orbits of Mars and Jupiter and gave it the name Ceres – in honor of the Roman goddess of fertility.

Less than a year later, Pallas, Vesta and Juno were found in the same orbit.

Too many planets, don’t you think? So it seemed to astronomers after they found another hundred of the same mini planets. Then it was decided to expel these four from the planets and call them asteroids, that is, “similar to stars.”

And in 1845, to the delight of astronomers, the eighth, already “real”, “big” planet, Neptune, was found. According to their calculations, the planet had to move in its orbit according to all Kepler’s laws. But she didn’t!

The planet moved as it pleased. It was obvious that something huge and heavy was either slowing down or accelerating Neptune. Scientists continued the search for the now mysterious “Planet X”.

For 85 years, astronomers around the world have been playing hide-and-seek with the ninth planet. During this time, they managed to find out the mass and size of the planet, with what speed it moves in orbit.

They just couldn’t find it. The mysterious, smallest ninth planet was discovered by the American astronomer Clyde Tombaugh in 1930. Yes, it was Pluto.

Why is Pluto no longer in the parade of planets in our solar system 2

However, the joy subsided rather quickly. Instead of a large and heavy planet, Pluto turned out to be quite tiny, six times lighter than the Moon.

And the orbit of the new planet turned out to be somehow inclined, and not “circular”. Sometimes Pluto flew up to the Sun even closer than Neptune (about four and a half billion kilometers), and sometimes moved away almost seven and a half billion kilometers.

After the discovery of Pluto’s satellite Charon in 1978, and the tiny 100-kilometer Albion in 1992, scientists suspected a repeat of the story with asteroids of 1805.

The last straw was the object discovered in 2003, which was named Eris. Scientists searched the entire sky and beyond the orbit of Neptune found hundreds of small similar planets – ranging in size from 50 to 2500 kilometers.

Rules for membership in the solar system

After all, in order for an object of the solar system to be considered a planet, it must meet the requirements defined by the International Astronomical Union (IAU):

  • The object must be in orbit around the sun. There are no questions for Pluto.
  • It must be massive enough to provide itself with a spherical shape by its force of gravity. And here with Pluto, everything seems to be in order.
  • It must not be a satellite of another object. Pluto boasts five moons.
  • It must be able to clear the space around its orbit from other objects. This is where Pluto gave a notch. This was the main reason to exclude him from the status of the planet.

Pluto, which was searched for as long as 85 years, it was decided to deprive the status of a large planet. It was recorded in the category of “dwarf planets”, of which today there are eleven pieces: Pluto, Eris, Haumea, Makemake, Charon, Gun-Gun, Quaoar, Sedna, Ceres, Orc and Salacia.

And this is not a definitive list. Scientists are confident that it will still be replenished.

They all revolve around the Sun, have enough mass for gravitational forces to form them into a spherical shape, but because of their small size, they are not able to clear their orbit from other objects.

Although Pluto is only the largest dwarf planet, it still continues to fascinate astronomers and remains in the memory of many people as the ninth planet in the solar system.


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