I notice from the front page of Wikipedia that the Solar System has a new younger sibling - Makemake ("ma-kay ma-kay"), one of the mysterious Kuiper Belt Objects, has been upgraded from "lump of ice" to "Plutoid", alongside Pluto itself and Eris, by this year's international convention of people who dedicate their lives to staring at indistinct objects billions of miles away that man will never visit.

It's speculated that it's so cold that it's covered in solid methane. So if you farted on Makemake you could watch it crystallize in the air and fall to earth. Cool!

I also notice that Pluto seems to have acquired a couple of extra moons: Nix and Hydra.

I have no idea what a Plutoid is. Is this the same as a dwarf planet (which I don't fully understand either)?

Although the international astronomy body can't agree on the definition of a planet either.

From Wiki:

A dwarf planet is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but which has not cleared its neighbouring region of planetesimals and is not a satellite.

A Plutoid is a trans-Neptunian dwarf planet, which rules out Ceres, for example, which is in the asteroid belt.

It's (a "planet") something to do with a body with a large enough mass that gravity pulls it into a broadly spherical shape, rather than being potato-shaped like most asteroids or comets, and has its own orbital path not dependent on other larger bodies. Our own moon would be a planet if it didn't orbit us, but just went on its own circle around the Sun.

The "planetoid" bit is something about bodies that satisfy the broad definition of "planet", but the authorities have decided that as there might end up being dozens of them, it would make the "Planets in the Solar System" far too unweildy for kids to memorise or learn, so they've pulled the rope ladder up at the traditional first 8 "planets". "Plutoid" just means "planetoids" that are out in the same area of space as Pluto, three identified so far but as I said there could end up being dozens. Mercury, strictly speaking, should also be a "planetoid" according to its size, but as Mercury is one of the 5 planet/planetoids visible to the naked eye, and we named a day of the week after it, they couldn't bring themselves to "relegate" it.

I've made this point on another thread, but these classifications are all very silly indeed.

To use a football analogy, it's like trying to define a 'big club' and a 'small club'.

Human farts (as opposed to those of ruminants) are mostly nitrogen and carbon dioxide. Methane is always a minor component, and 2/3 of people don't secrete methane at all. The main inflammable gas in farts is, apparently, hydrogen.

So you'd have a one in three chance of expelling a tiny pellet of methane? Weighed up against the terrible piles it would give you, I'd say it wasn't really worth the risk.

I think the fart thing is all to do with which populations of bacteria populate your large intestine when you're very small.

If you're lucky you get methane-producing bacteria (methane is odourless). If you're less fortunate, you get bacteria that produce sulphide.

Not sure that can be right, WE. If you ignite hydrogen in air you get one hell of a bloody big bang, not a neat little blue flame like I've seen coming out of Rugby players' backsides at after-match dinners.

I was a bit sceptical but I think WE's right. (My point was related to smell rather than flammability.)

Rogin the Armchair Fan wrote:

QUOTE:
Not sure that can be right, WE. If you ignite hydrogen in air you get one hell of a bloody big bang, not a neat little blue flame like I've seen coming out of Rugby players' backsides at after-match dinners.

Depends on the relative proportions of H to O.

Returning to the topic in hand, rather than changing the definition of planets ever year (and inventing arbitrary new variants), why don't they define a planet along the lines of:

"Anything in primary orbit around the sun that you can see from earth with a really good pair of binoculars."

"really good" ?

Definition...?