Discover magazine runs two letters this month that bring up two more problems with the International Astronomical Union’s criteria for planets. Jerry Svoboda points out that because Neptune’s orbit is crossed by Pluto, Neptune fails to “clear its zone,” thus failing one criterion for planethood. Brett Bochner argues (in a reductio ad absurdum sort of way) that Jupiter is 300 times larger than the Earth and is made almost entirely of gas, and thus shouldn’t be lumped with the Earth.

Fortunately, I have the solution.

Everyone knows the IAU’s tortured criteria were designed to give us back as many of the nine planets as possible. Even so, the IAU failed. At best we got eight planets and one dwarf. So, let’s skip all the weird distinctions and just declare the Solar System a constellation. After all, no one says that some other star really “deserves” to be part of Ursa Major even if it means the bear now becomes a unicorn. Nope, a constellation is what we say it is, and the same is now true for the nine planets of the Solar System.

Welcome back, Pluto!

[Tags: taxonomy everything_is_miscellaneous IAU planets pluto solar_system astronomy taxonomy]

Categories: Uncategorized dw