Pluto No Longer a Planet

[Dave]

At last the International Astronomical Union (IAU) has defined exactly what is and what isn't a planet. Poor Pluto gets the boot but common sense wins.

I won't go over all the arguments (it would take too long) but there's one thing I'd like to mention that has escaped many commentators - the impact on education if this decision had not gone the same way.

Some people are worried that the textbooks will have to be re-written now that there are only 8 planets in our solar system. This is true, but it would be a lot worse if Pluto was still a planet. Basically, if Pluto is a planet then so are at least two other objects, meaning that text books would need to go from 9 to 11 planets. The real problem is that every time a new object is found (and this expected to start happening more regularly) the text books would be out of date again. At least the 8-planet decision only means one major update.

Of course some text books will still need to include newly-discovered "dwarf planet" objects but that's not a big deal and doesn't affect nearly as many books.

And finally, the impact on kids and people new to astronomy. Learning 8 or 9 planets is manageable. 20 planets would be more of a test, but what happens when we're up to 50 planets?

I think it's desirable to keep the basics of astronomy accessible for everyday people. Learning the 8 planets is a good entry-level task which provides good groundwork for understanding the solar system. I'm glad it still works like this.