Yes, There Are Only 8 Planets Instead of 9 Because There Used To Be Just 5.

Rhett Allain
8 min readFeb 21, 2022
Photo:Rhett Allain. Jupiter and Saturn in the sky.

Some people were super upset when it was decided that Pluto should not be called a planet. I mean, countless students had grown up memorizing the following sentence:

My Very Excellent Mother Just Served Us Nine Pizzas.

Of course, this is a mnemonic to help us remember the VERY IMPORTANT order of the planets in order of increasing distance from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. But who would actually order 9 pizzas? It must be a pretty big party.

And yes, this will be on the test. I mean, if you don’t know that Uranus is closer to the Sun than Neptune then you can’t survive in the real world. It’s super important (I’m kidding). Also, while we are talking about Uranus let’s get this out of the way. If you want to pronounce it as “your anus”, I’m fine with that. I’m also cool with “your a noose” as long as that makes you happy. For me, I like to say “OO ra noose”. It just sounds cool and it throws people off.

OK, I’m going to get to this Pluto thing — but let’s start at the beginning.

Humans Discover Planets

No one remembers the day it happened. No one even remembers the name of the human that first figured it out — but someone (let’s…

--

--

Rhett Allain

Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. WIRED blogger.