i suppose by now, just about everybody has heard that pluto no longer has the status of a planet.
most reactions i found on the net were pretty disappointed ones.
and i can’t really see why: pluto’s orbit around the sun is nothing like the “real” planets’ – it’s tilted and elliptic. apart from that, its own moon (charon) is so big that many scientists consider the pair a double planet, and there are several other bodies in space that are far bigger than pluto!
in highschool, i was really annoyed that we also had to learn the “historic direction” of electric current (the positive charge flowing towards the negative pole).
it was wrong – maybe because it was just what somebody imagined it would be – and imho it doesn’t do any good to modern physics (or does it?). so why do they still teach that at schools?
as for pluto, i’m glad the “historic” criteria didn’t make it.
and regarding the mnemonic that can’t be used anymore, ze frank has found an alternative you should consider (though it’s not very kid friendly):
what kind of an argument is that in the first place?
we can’t change definitions, because we’d have to find a new mnemonic?
a scientific committee of more than 400 astronomers has agreed on new definitions for the term planet – and pluto keeps orbiting the sun anyways. why bother?
on a funny side note, a disney spokesman told reuters that “pluto is taking this news in stride, and we have no reason to believe he might bite an astronomer.”