Pluto Could Still Be A Planet! (Who Cares?)


All right, that title was a little harsh, but I think you get the point. It’s not that I don’t love Pluto, Pluto is a fine little planet… dwarf planet… hold on, plutoid. It holds a certain charm and mystique, plus we have the mother of all NASA missions (New Horizons) gliding its way to the outer icy reaches of the Solar System — the Kuiper Belt to be precise — to take a look at Pluto, up close, for the first time. I can’t wait for 2015 when the spacecraft starts taking snapshots, it will be awesome.

But what of the small planety-thingy’s status? Is it still a planetary outcast, destined for a life on Cosmic Skid Row? Or is Pluto about to get the mother of all reprieves and be re-classified as a planet? Does it really matter?

The reason why I ask is that the whole “demotion” thing was seen as bad news. I actually saw it as an exciting development in Solar System exploration (but hoped it wouldn’t tarnish the little rock’s popularity all the same). In actuality, Pluto is 27% less massive than the recently discovered dwarf planet Eris, so how could Pluto still be called a planet? Should Eris be classified as a planet, then? In light of new dwarf planet discoveries, Pluto became a rounding error and had to be re-classified. The International Astronomical Union drew up some planetary rules and found that Pluto didn’t have the gravitational clout to clear its own orbit and so was re-classified as a dwarf planet in 2006.

Suddenly, Pluto had “fans” that took the re-classification personally and got angry at the IAU for throwing Pluto out of the planetary club. Their reason? Only 4% of IAU members were present for the re-classification vote, they saw it as a personal slight against the “9th planet.” Even the nutty state of Illinois was FURIOUS and reinstated Pluto as a planet… (just in the state of Illinois).

We’ve heard this emotional story of planetary bullying over and over, so I won’t go over the details again. The whole Pluto story has been widely covered, many people pointing the finger at the evil IAU 4%, some have even gone as far as saying this is evidence that there is a growing rift between the public and scientists (let’s take national votes on scientific decisions! That would be fun). But what does it really matter? Really.

Is the Pluto re-classification a breech of our human rights? How about planetary rights? Is it indicative of the number of idiot scientists who voted in the 2006 IAU poll? Is this an indicator of poor scientific thinking? Could a war be sparked over this atrocity? Was it really a ‘bad’ decision?

Just so my opinion is known, I don’t care what Pluto is called. If NASA decided to explode Pluto as part of a Kuiper belt clearing project, then yes, I might be a bit annoyed; I’d even start a blog titled “Save Pluto.” But calling Pluto a dwarf planet (or the rather cute plutino) really doesn’t bother me. It’s a consequence of scientific endeavour, despite the perceived “controversy.” As the legendary astronomer Patrick Moore said, “…you can call it whatever you like!” Pluto is still Pluto.

However, it looks like Pluto might be re-classified again… big yawn.

This time, heavy hitter Alan Stern, Principal Investigator for the New Horizons mission, weighed in with his opinion on the matter. “Any definition that allows a planet in one location but not another is unworkable. Take Earth. Move it to Pluto’s orbit, and it will be instantly disqualified as a planet,” Stern said.

This implies that if Earth was moved to the Kuiper belt, as things move a lot more sluggishly out there, a planet with the gravitational pull of the Earth couldn’t clear its orbit, therefore the “must clear its own orbit” criteria is a bad location-based definition for a planet. (I would argue that there’s every possibility that Earth could clear it’s own orbit at that distance given enough time, but what would I know, I’m no planetary physicist, but everyone seems to have an opinion about Pluto, so there’s mine.)

This analogy is a bit like saying a car driven down a country lane is a car. But a car driven on a freeway is a bike.

There is the counter argument to this case; if there was something as big as Mars, or even Earth, it may have tunnelled out a path through the Kuiper belt, thereby clearing its orbit. Alas, there appears to be no solid consensus as to the nature of this littered volume of space (at least until 2015), hence all the fuss.

Now there’s some big noise that the IAU will reconvene and discuss the Pluto hoopla again, giving a vague glimmer of hope to pro-planet plutonites that the 2006 decision will be overthrown. Alas, I very much doubt that as, quite frankly, there are more pressing (and more interesting) matters to discuss such as: what the hell hit Jupiter?! We should re-classify Jupiter as ‘the inner Solar System’s gaseous protector’!

Source: New Scientist