9th Planet

[KILROY]

Pluto has not cleared the area of its orbit. It's located in the Kuiper belt. If we were to classify it as a planet, several hundreds of things would meet the criteria. Especially the other dwarf planets Ceres, Eris, Makemake, etc. The IAU changed the definition in 2006 because of this issue. My 8th grader's have no trouble understanding this when I teach them my space and solar system unit. No offense. But we were also taught that it was a planet as kids. Just goes to show you how hard it is to change someone's core ideals even when they are wrong.

https://en.wikipedia.org/wiki/Definition_of_planet

As Wikipedia clearly states "it's an argument" Wikipedia is written by public people, not scientist. My link is written by NASA's scientist, the people who make this up. I respect my links statement, the founders of the definition, before something written by public people.

[perrinoia]

Just goes to show you how hard it is to change someone's core ideals even when they are wrong.

What your wiki article says, is that some people (like you) changed the definition of the word "planet" so as not to include Pluto and the other trans-Neptunian objects, rather than add the new objects to the list of planets.

It also says that other people (like myself) reject the new definition, but doesn't explain why... So I'll explain:

This definition, which applies only to the Solar System, states that a planet is a body that orbits the Sun,

Why limit it to only our solar system? We are aware of objects that orbit other stars, and have referred to them as planets since discovery. Now we must call them something else simply because they don't orbit the Sun? Pluto does orbit the sun, but it is also effected by the gravitational forces of it's own moons. If you think Earth isn't effected by the gravitational pull of it's moon, then you must not know what tides are.

is massive enough for its own gravity to make it round,

Earth isn't perfectly round... There are mountains and valleys. The oceans have tides, and it's only logical to assume the atmosphere has tides too... The shape of Earth is constantly changing, and does not fit this definition without a considerable allowance for variance. Likewise, Pluto has a weird shape, which stays relatively the same throughout it's winter, but when it's orbit brings it closer to the sun than Neptune, it's atmosphere thaws and changes shape. When you stand on Earth's surface, it appears flat. When you look upon Earth from orbit, it appears round, and if you look away, it doesn't appear to exist at all. It's all a matter of perspective, and from my perspective, Earth is no more perfect than Pluto.

and has "cleared its neighbourhood" of smaller objects around its orbit.

Again, are we forgetting about the moon? Are we forgetting about the comets and asteroids, and meteors? Has Earth cleared it's neighborhood of smaller objects around it's orbit? No... No it has not. So, one again, I argue that by this new definition, Earth is no more a planet than Pluto.

But what bothers me the most about these claims of discovering a 9th planet, is that we haven't even seen it yet! How do we know it fits the new definition of a planet better than Pluto? How do we know it's not a tiny black hole, caused by the large hydron collider? I'm pretty sure it's not that, but I'm not a physicist nor an astronomer. Heck, all we know about it, is that there is a slight disturbance in the orbits of some celestial bodies, and mathematics hint at a gravitational force akin to an unseen object, roughly the size of a planet. What is the size of a planet, again? Does Jupiter (a gas giant) count?

The defense rests, your honor!

[KILROY]

BRAVO!!!!

[DaRk]

That is the definition by the IAU (International Astronomical Union), which includes scientist from NASA and all over the world. Regardless if its a wikipedia article, the definition currently remains. It was voted on in 2006. It will probably change as we learn more. Just as the ICS (International Commission on Stratigraphy) votes on changes in the geological time scale based on best fit evidence. It can get a little political, look up the Ediacaran/Vendian issue. Russians mad.

The exoplanets we discover are considered planets cause we can not see things such as small asteroids or meteroids that may surround them. They reflect too little light for us to detect. If we could, some would be dwarf planets by the current definition.

It's called hydrostatic equilibrium, aka nearly round shape. No where does it say it has to be exactly round. It has to orbit a sun, not our Sun to be specific. The gravitational pull of a moon or other planets (Jupiter has a large gravitational impact on planets and other objects in our solar system), but it does not impact the current definition of a planet.

Lastly, the moon orbits us. Making it not in our neighborhood but in equilibrium with us. Where as Pluto and its larger moon Charon orbit each other (think of false start signal). The tides are a combination of both the moon and suns gravity. Eventually, the moon will become tidally locked with Earth and will have drastic changes in our tides. Your understanding of 'clearing the neighborhood is flawed. The difference is that Earth makes up more than 99% of the mass around its orbit, so it is considered cleared. Where as Pluto only makes less than 1% of the mass of the Kuiper belt it is located in.

Don't go B.O.B. on me here Perrin. I don't mind you disagree, but your arguments are scientifically flawed. Science is constantly changing to fit new evidence. That's the greatness behind it. Don't get stuck in the past.

[KILROY]

I understand what you are relaying Dark, but may want to read my article on what NASA is relaying.