Okay, everyone. Sit down, pull your socks up, and get ready because another group of scientists wants to make Pluto a planet again. Back in 2005, some asshole named Mike Brown thought he discovered a new planet, but it was too far from the sun and was too small. The discovery of this almost-10th-planet led to Pluto's ultimate demise: scientists realized that Pluto did not meet their definition of a planet. Mike Brown didn't care. In fact, he released a book about it. We don't like this Mike Brown.
As of now, in order for something to be a planet it must, "(a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and (c) has cleared the neighborhood around its orbit." So, parts A and B make sense. They're pretty straight forward. A planet must orbit the sun and be nearly round. But part C is where things get tricky. What exactly does it mean to "clear the neighborhood around its orbit"? Does that mean that there can't be anything there? Does it mean it can't have anything above a certain size? What? Because, realistically speaking, none of the current "planets" are actually planets by this definition. They all have something in their orbit.
But why? It wasn't Pluto's size, or even the distance from the sun. It was because Pluto's orbit crosses Neptune's, and according to the current definition planetary orbits cannot cross each other. But why did they choose Pluto and not Neptune? Because they hate Pluto those assholes. In case you can't tell, I'm super bitter about this. I care a lot about Pluto, which is why I was so excited when I found out that New Horizons (the group of scientists I mentioned) wants to make Pluto a planet again.
So, how did this happen? How will Pluto become a planet again? Well, New Horizons wants to redefine what a planet is. They want to change the definition of "planet" to "any sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape and adequately described by a triaxial ellipsoid regardless of its orbital parameters." Basically, all round objects that are smaller than stars. In space, obviously.
This new definition would add not only Pluto, but hundreds of other "planets" to our Solar System. That would definitely make memorizing the Solar System difficult! Sadly, this proposal hasn't been submitted yet and New Horizons isn't even sure if they will submit it. Keep your fingers crossed that they submit it!
So, all you 90s kids, get your party hats ready because it could happen. Our cute, icy little rock could be a planet again.
