Why is Pluto, the dwarf planet of the solar system, no longer considered a planet?


Pluto, formerly the ninth planet of the solar system, was downgraded to a dwarf planet in 2006.
Margherita Erriu Margherita Erriu 4 minutes

Years ago about the discovery Pluto its existence was already assumed due to some anomalies in the movement of Uranus and Neptune. In fact, the two planets moved in space as if another object disrupted their trajectory due to gravitational attraction.

Arm yourself with a lot of patience a number of astronomers years, therefore, they observed the sky in search of the so-calledplanet“. What they didn’t know it was actually that Abnormal behavior in the motion of Uranus and Neptune did not come from the presence of a the third planet with which they gravitationally interacted, but from one incorrect estimate of Neptune’s mass.

Discovery of the ninth planet of the solar system

Therefore, despite completely wrong assumptions February 18, 1930 astronomer Clyde Tombaugh he discovered what he longed for the ninth planet.

However, within a few years it was discovered that this new planet did too small to be the one who has influenced the movement of Uranuswas therefore not responsible for orbital peculiarities but it was still discovered, there were in fact gods heavenly bodies in motion around our star, but with outer orbits compared to Neptune.

As time passes researchers improved their knowledge on this planet we are actually aware some important differences between it and the other 8 planets our planetary system.

First, as already mentioned, Pluto is really tinyabout average only 2,376 kmequal about half than that Quicksilveranother very small planet and her Surface it shows covered with ice. Not only that, but his circulate era strange, very inclined and very flattened. These quirks do look like Pluto and its movement more like a comet than a planet.

But it didn’t work depose Pluto into the role of a simple comet, because she still had one important analogies with other planetsas spherical shape and the fact that we have gods satellites.

Differences and similarities with other planets, clarity is needed

It comes from here need to be defined Therefore what features make a celestial body a planet. For this reason in 2006 L’Astronomical Union solid 3 criteria decide whether the object is a planet or not: he had to orbit around the sunmust have had such a gravitational force that it had a spherical shapeand finally he had to have one enough mass to clear its path of debris.

Alas, Pluto failed all 3 requirements but only the first 2 and for this reason he came demoted to a dwarf planet.

As of 2006, the planets are therefore the solar system back to 8while I dwarf planets there are currently 5 of them: Ceres, Pluto, Haumea, Makemake AND Eris. Instead, there are other celestial bodies pending classification exact.


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