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Knowledge of our solar system changed drastically in 2006. Before then, most of us knew there were nine planets in the sun’s solar system. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. There were even rhymes to remember it. Then, in 2006, the International Astronomical Union said that Pluto was actually a dwarf planet. The controversial statement caused an uproar worldwide: How could Pluto not be a planet? Was Pluto now no longer part of the solar system? Were we all living a lie? So what’s the status now? Is Pluto a planet?

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How Was Pluto Discovered?

Pluto was discovered in 1930 after astronomers set out to find the ninth planet in the solar system. A world they had dubbed, 'Planet X.' As this was going on, a 24-year-old astronomer named Clyde Tombaugh carefully studied pictures of the night sky. That was when he noticed what appeared to be the yet-to-be-discovered planet. Pluto's name came from the mind of an 11-year-old girl, Venetia Burney, who suggested the new planet be named after the Roman god of the underworld.

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Who Said Pluto Wasn’t a Planet?

In 2006, there was a controversial statement denouncing Pluto as a planet. This came as a shock to most people, and it was met with criticism, despite being a statement by a professor of astronomy. That professor's name was Dr. Mike Brown who soon became known as "The Man Who Killed Pluto." He's aware of the public's sentimentality towards the reclassified dwarf planet but stands by everything he said.

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Why is Pluto Not Considered a Planet?

When Pluto was discovered, it was mistakenly thought to be as big as Jupiter. In fact, it's smaller than our moon. To be fair, from its discovery, Pluto was the misfit of the solar system. Not only did it go undiscovered for so long, but there were dwarf planets that were even bigger than it was. For scientists, that meant that if they classified Pluto as a planet, those bodies such as another dwarf planet, Eris, would also have to be considered planets. Funnily enough, it was Eris's discovery that put the wheels in motion for Pluto to be denounced.

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What Are the Criteria for a Planet?

Three criteria are taken into account when naming a full-sized planet. The requirements include that it's in the Sun's orbit, is round, and has objects of a similar size in its own orbit. Pluto was nearly there, checking two of the three, but it falls at the last hurdle. Therefore Pluto, scientifically speaking, is absolutely not a planet. It’s a dwarf planet.

dwarf planet pluto dottedhippo / Getty Images

What’s a Dwarf Planet?

Dwarf planets appear similar to full-size planets, but they don't fit the scientific criteria. They also usually don't have the size. Neither planets nor satellites, dwarf planets are celestial bodies that orbit the sun. Unfortunately, that's about it. Our solar system has five dwarf planets, including Pluto, which is the biggest.

pluto and charon moon NiPlot / Getty Images

Is Pluto Still Part of the Solar System?

Yes. Although astronomers declassified Pluto as a planet, that doesn’t mean that it isn’t still in the solar system. Our solar system is divided into three zones. Its first zone consists of Mercury, Venus, Earth, and Mars. These are the planets closest to the sun and are dense with rock. The second zone belongs to Jupiter, Saturn, Uranus, and Neptune; gas giants with surfaces largely made of ice. Then, there's the third zone. For most, Pluto might even be the only recognizable name in it. It, alongside other dwarf planets, make up what's known as the Kuiper belt. One of the biggest structures in the solar system.

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Is it Still Classified as Number Nine?

Removing Pluto's place as a planet meant dropping it from the nine planets as we knew them. The uproar it created was intense, but it made sense. For school kids these days, there are only eight main planets. As hard as this is for some of us to get our heads around, it’s just the way it is. Reinstating Pluto as a planet would mean making hundreds of other celestial bodies the same.

pluto rendering with galaxy dottedhippo / Getty Images

Are Other Dwarf Planets in the Solar System?

As well as Pluto and Eris, there are three other dwarf planets in the solar system. These two are almost the same size where the others are quite a bit smaller. Haumea, discovered in 2003, has a strange, elongated shape. Two years later, in 2005, astronomers discovered Makemake. Its name is Polynesian in origin, referring to the Polynesian god of fertility. Lastly, there's Ceres. Astronomers first spotted Ceres in 1801, and it was, at first, classified as a planet and then an asteroid. Ceres is also the closest planet to us on Earth.

pluto lit by sun dottedhippo / Getty Images

Can Humans Live on Pluto?

As the option of interplanetary travel begins to look more and more possible, we find ourselves asking which planets could be livable. Pluto remains the strangest and most confusing object in the galaxy that we know of. We have no idea whether or not it could sustain human life or not. What we do know, however, is that Pluto is only half as wide as the United States. That and one year on Pluto is 248 Earth years. Is Pluto, therefore, the fountain of youth?

lonely planet pluto dottedhippo / Getty Images

Is Pluto a Planet Again?

In 2015, the Pluto debate came back with a vengeance. After all, it wasn't just the general public who disagreed with Pluto's declassification. Scientists such as Alan Stern, the principal investigator of NASA's New Horizons mission, felt the same way. The New Horizons mission sparked Stern and another planetary scientist, David Grinspoon, to write a book that states that Pluto is, indeed, still a planet. So, is Pluto still a planet? If you ask the experts, it is if you want it to be.

solar system planetarium toy SolStock / Getty Images

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