Physicists should not be precious about words
A working group set up by the International Astronomical Union (IAU) is expected to announce shortly that the word "planet" should not be used without an adjective like terrestrial or trans-Neptunian in front of it. The definition of a planet has become a hot topic following the discovery of several objects that are comparable in size to Pluto. Are they planets or not? Indeed, is Pluto a planet? If the proposal is accepted by the IAU, the word planet, like quite a few other, everyday words (weight, work and so on) will mean one thing to scientists and another to the general public. Some scientists get needlessly worked up about these words, but there are few things more pointless in life – or physics – than criticizing people who confuse mass and weight. It would be a great shame if we could no longer use the word planet on its own without fear of condemnation.