fish4096 t1_jb99khb wrote on March 7, 2023 at 11:43 AM

Reply to comment by dave_hitz in TIL the largest moon in our solar system, Ganymede, is larger than the planet of Mercury by Jugales

i'm pretty sure the orbit is going to clear boundary. but i know what you mean, i'm still salty about Pluto, too.

dave_hitz t1_jbbgxw2 wrote on March 7, 2023 at 9:06 PM

I agree about the clearing. But they'll invent some new rule. "But it's smaller than a moon in the same solar system!"

I have a simpler rule. If it's big and round, it's a planet. Unless it's burning with the flames of a nuclear fire, in which case it's a star.

Some planets go around stars. Some planets go around other planets.

Let the planets proliferate.

fish4096 t1_jbdutkc wrote on March 8, 2023 at 9:43 AM

gotta have clear definition of "big" then.

By diameter? Mass? Bigger then what?We could of course take Earth as ballpark and drive rules from there, but this wont get us far the more of universe we discover. There will be all kinds of odd objects that dont fit into our little bubble of categories.

The reason I'm upset about Pluto is because it's one of those "classic" discoveries, something that should be honored.

dave_hitz t1_jbfgcfu wrote on March 8, 2023 at 5:47 PM

Big enough for gravity to squeeze it to round. Most asteroids are odd shaped rocks. They don't count. Get enough rocks to generate enough gravity to pull the rocks into a sphere, then you've got a planet.