Apropos history and Jupiter's moons - students might want to be reminded that Ceres was counted as a planet for half a century or so before being demoted, upon the discovery of the 'other' asteroids in that vicinity.
And Gauss played a major role in the 'rediscovery' of Ceres once it reappeared from the sun's glare.
And it would have once again been 'defined' to be a planet if it had done a better job of clearing out the other asteroids in its vicinity. (or if such clearing-out was not included in the (current & somewhat arbitrary) 'official' definition of a planet.)
----- Original Message -----
From: John Clement <clement@hal-pc.org>
To: 'Forum for Physics Educators' <phys-l@carnot.physics.buffalo.edu>
Sent: Sun, 18 Oct 2009 14:40:41 -0400 (EDT)
Subject: Re: [Phys-l] DATA, FACTS, LAWS, THEORIES
As to there being 4 moons of Jupiter, it is easily made into a fact by
saying there are 4 Galilean moons of Jupiter. This makes the definition
exact in historical terms. One can easily get balled up in the question are
there 9, 12, or 8 planets around Sol. It is a matter of definition, and is
not worth arguing. There are historically 9 planets. This may be a good
topic to bring up with students and give them the information about masses
of the various large objects including the ones outside of Pluto's orbit.
Then let students decide and debate what they think before presenting the
standards group's thinking.