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Yeah, Pluto is just too little.

Just another Perl hooker - Selling my %hash for $cash.

Pluto-Charon should be classified as a Binary Planet (just like Sirius is a Binary Star)

Pluto remembers when it was Planet Nine.

Slashdot: A New Definition Would Add 102 Planets To Our Solar System -- Including Pluto

Alexander

As far as i am concerned it never lost it's "planethood". I am not constrained by idiots who decide silly things by their own silly rules.

bump... agreed

We constantly redefine our world based on new information. Things get re-classified. Hell, I am now classified as 'old'! :-)

Is Pluto a planet? Does it qualify? For an object to be a planet, it needs to meet these three requirements defined by the IAU:

• It needs to be in orbit around the Sun – Yes, so maybe Pluto is a planet.
• It needs to have enough gravity to pull itself into a spherical shape – Pluto…check
• It needs to have “cleared the neighborhood” of its orbit – Uh oh. Here’s the rule breaker. According to this, Pluto is not a planet.

The definition of planet the IAU came up with in 2006 was shortsighted. It was crafted to make sure that only bodies that formed from the accretion disk are planets, hence the third definition part. (By the third part, Neptune is not a planet since it has not finished clearing Pluto out of its path.)

Their whole definition falls apart when applying it to the almost weekly announcement of new planets orbiting other stars (which also violates the first part.) Do we know if those new planets have cleared their paths? Do we know if they are all in their ecliptic planes? We don't even know if they are spherical (although I don't know how they couldn't be for the size we have been finding.)

Why should it matter how a body got into orbit around a star? If we have a huge round ball orbiting, it is a planet. Doesn't matter if it is in the ecliptic or 90 degrees off. Doesn't matter if it was born there or left on the doorstep from a close stellar encounter. Should we do the same for moons? Jupiter has four moons and umpteen dwarf moons? Mars has no moons?

I would rather say we have dozens of planets orbiting the sun than the current artificial distinction. Modify the definition above to replace sun with star in the first part and get rid of the third part completely. Then just live with the idea that there are still planets orbiting the sun waiting to be discovered.

The page I linked to earlier mentions that

In the new paper, which the scientists plan to put forward to the IAU, the current definition is described as "technically flawed" - it only recognises planets as objects that are orbiting our Sun and not other stars. It also says the need for zone-clearing means "no planet in our Solar System" meets the criteria for planets.

The authors argue the new definition is "geophysical" and based on the physics of the world itself.

So e.g. if the positions of Earth and Pluto were swapped, the Earth would no longer be a planet according to the IAU's definition.

The paper they refer to is short and readable.

We constantly redefine our world based on new information.

But what's the point?

When classification for the purpose of helping or understanding, reclassification helps. But what does reclassifying what a planet is help? Classification for the sake of classification doesn't seem to be very popular.

But what does reclassifying what a planet is help?

Reclassification becomes necessary when our thinking (or models, if you will) on a certain subject cannot jive or be sustained given the new findings. (Re)classification is going on all of the time. There is already substantial resistance to it since doing so means rerunning potentially thousands of experiments and rewriting a very many papers/textbooks on anything involving it. Imagine how many things had to be rewritten/done when Einstein's theories were verified!

Let me be clear that there is no classification for its own sake going on. The sheer amount of work and potential embarrassment involved if your findings are unsound is enough to keep most people in the scientific community from doing virtually anything trivial.

Celebrate Intellectual Diversity

Apparently, even Earth hasn't cleared it's orbit: pesky Asteroid 2016 H03. We live on a dwarf planet!

You forgot one... a planet's orbit should be distinct from other planets' orbits... in other words, two planets' orbits should not cross paths... This is true for the other 8, but Pluto cuts across Neptune's orbit, which is a big no-no.

in other words, two planets' orbits should not cross paths

And why is that Pluto crosses Neptune's path? Why not the other way around? It's not like Neptune hasn't done this before.

I just call it an "honorary planet".

Why does this poll only have two options? It's missing: Whatever, I don't care, and All of the above.

With those options, it would be harder to Make Pluto Great Again :)

I propose a middle ground. Let's have "planets" include "dwarf planets". We can have "major planets" and "dwarf planets" and call them all "planets" when there's no reason to distinguish between the two.

We can have "major planets" and "dwarf planets" and call them all "planets" when there's no reason to distinguish between the two.

Wow! That's actually a great idea.

It's orbit is tilted out of the ecliptic. The orbit is sufficiently irregular that it comes inside Neptune's (every umpty-ump years...). It just doesn't match the established pattern. A reg-exp that matches "planet-like" chars would not match Pluto (sorry Percival).

Hey now, who *wouldn't* want Saturday, Saturday-2, Sunday?

$management

Unless I missed it I'm a bit surprised that no one has mentioned that the search is presently on for the mysterious Planet 9 in our solar system. Evidence suggests that is should be there but there is a very large space where it could be apparently. NASA is crowdsourcing the search right now, so those you desperate to return to the Nine Planet Realm can participate!