Pluto

Many years ago, when I was at school, I was taught that there are nine planets in our Solar System.

One day, slightly fewer years ago, the Interplanetary Council met. On Jupiter, not because they are the biggest but because it's their turn. A motion was presented by the Chairthing, to the effect that "Pluto is too small to be part of our club. Our next meeting is due to be there and it's just too cold. They should  be relegated to the Second Division". "And it is 3,638.5 million miles away" piped up the little Mercuryling "and I wouldn't get back in time for Neighbours". "Best keep quiet, little Mercuryling" croaked Saturnbeast, "you'll be next in line".

"Wait a minute, we orbit the Sun don't we?" spluttered the Plutothing. "Once a day [that's a Pluto day; 248 earth years]. That's what planets do, isn't it? In any case, it only took us 20 earth-minutes to come here today." Now Pluto is the only one of the planets with teleport technology, so that's why they got there quickly. You might have thought to ask "how did you get here so fast" but the real question is "why did it take you so long?"

You would have thought that the other planets would have cosied up to the Plutonians, to do a trade deal - maybe some of our nice plutonium deposits in exchange for your teleport tech? "Don't be silly, we have our own plutonium - why do you think we are called Pluto?" "I thought you were named after Mickey Mouse's dog" whined the Marsling.

"Enough; we should vote" the Earthling intoned. Of course, ever the diplomats of the Solar System. They voted: 8 to 1 for the relegation of Pluto. Now there are only eight planets. But who will be next? The Mercuryling is keeping quiet on that one.

The Second Division is now a club of five planets - Pluto, Ceres, Eris, Haumea and Makemake [that's a name? Did someone makemake that up?]. They are known as dwarf planets. I don't think that's a politically incorrect term, as dwarfism is a known medical condition. Except for Ceres, which lies in the main asteroid belt, these small planets are located in the Kuiper Belt. That's just around the Kuiper Waist and holding up the Kuiper Pants.

Pluto is not even the biggest of these. That's Eris, whose diameter is 1,445 miles against Pluto's 1,430. Close.

Space.com tells me that the debate over Pluto's status continues:

The debate started anew after the New Horizons mission passed by Pluto in 2015, revealing a world of surprising geological complexity. As of 2017, delegates from the mission [wait! They've travelled more than 5 million km to get here? Wow] are trying to get Pluto's planethood status back. 

The primary concern stems from the requirement for a planet to clear out its local neighborhood [ah, those pesky plutonium dealers on the street corners, that's the problem?].

'In no other branch of science am I familiar with something that absurd," New Horizons principle[sic] investigator Alan Stern told Space.com in 2011. "A river is a river, independent of whether there are other rivers nearby. In science, we call things what they are based on their attributes, not what they're next to.'

Yep, I'm with you, Al. #GetPlutoBack

How does a mere blogger know this esoteric stuff? Research, mate, that's how. With a bit of help from NASA.