xkcd #3063: Planet Definitions
Planet Definitions
Under the 'has cleared its orbital neighborhood' and 'fuses hydrogen into helium' definitions, thanks to human activities Earth technically no longer qualifies as a planet but DOES count as a star.
He's mixed up the first two diagrams - Pluto should be coloured in for the first and not for the second.
He fixed it. They're swapped now.
This is really really frustrating to me, very unlike Randal.
What's worse is he's got Neptune's moon highlighted in the first row
Ultratraditionalist is messed up too. The sun and moon were considered planets when geocentrism was king.
It comes from the fact that the word planet comes from the Greek and means wanderer. Any celestial body that wandered around compared to the stars was considered a planet.
The judgemental one has 7 coloured instead of 6 too.
Good catch - he's updated the graphic but this is still wrong.
Laughed at the alt text, you have to be careful with definitions!
Yeah, I hope I find opportunities to mention that in casual conversations.
Atheist: Only planets that were discovered before God created the universe 6000 years ago are planets.
(Earth, Moon, Mercury, Venus, Mars, Jupiter, Saturn)
https://en.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_moons
I think the diagrams for 1 and 2 are swapped.
I guess I'm spiteful
For some reason this subject always hits a nerve, but I found this take pretty funny. Almost like when you experiment with regex matching randomly and find everything but what you really want to get.
It also wouldn't be a joke or topic if the definition had been clarified better than it was initially. They should have used the term "dynamical dominance", implying whether or not a body is the primary object left in its orbital area after formation. And this has its own issues, as solar systems change over time.
For some reason this subject always hits a nerve
Always bothers the hell out of me because of the politics that went into defining an arbitrary rule that makes no sense for identifying something that the rest of humanity has to obey, as well as that planetary scientists did not make the decision astronomers did, as well as that just a small subset of the international governing body voted the rule in, and not most/all of them.
Scientists should know better. They should not 'just call it a day' then make money by arrogantly selling books on the subject.
It's bad Science.
They should have used the term “dynamical dominance”, implying whether or not a body is the primary object left in its orbital area after formation. And this has its own issues, as solar systems change over time.
What does the environment around a body have anything to do with classifying the body itself? How would the body magically change if the area around it became crowded? It's a nonsensical criteria.
what is the name for things in orbits that aren't asteroids ?
Satellite.
Can also be broken down to natural and artificial satellites, but natural has extra requirements than just being naturally occurring.
Debris?
I mean including things like planets, an umbrella term that planets are always on
it doesn't sound to me like you could just say a planet is debris although I do think the formation of the moon could technically be space debris so maybe other larger celestial objects may have originated as such
I'm a computer person. not a space or physics person so forgive my lack of correct terminology
do we have a saturn moon with surface oceans? thats very cool!
We do. Titan is the only other body in the solar system with surface seas and lakes. They are made of hydrocarbons like ethane and methane however, not water.
Really love this comic
I still want it to be called an honorary planet. I feel like that's the best solution.
The solution is that milleanials and older should be allowed to call it a planet, while everyone else doesn't really care. This way the problem solves itself once we all die.
This solution applies to many things, like using neo pronouns, using new versions of grammar, etc. Make it opt-in for old dogs.
You are allowed to call it a planet. Everyone has the right to be wrong about stuff.
I realize the comic is good natured, but I feel the need to be serious for a moment, and say something...
Any rule that would disqualify Earth as a planet, if Earth and the other planet switched places, it's a bad rule, and should not be used.
Humans don't stop being humans, if they are standing alone one day, and are surrounded/crowded by other people the next day.
Also, having a single handful of people decide for the species what the definition of a planet is, and then some of them sell books about it, it's not good science.
Planetary Scientists really need to step up, and decide this.
Pluto should never have been lumped in with the planets in the first place. Its orbit is so weird and slanted it's discovery should have been celebrated as the new type of celestial body that it is.
Pluto should never have been lumped in with the planets in the first place. Its orbit is so weird and slanted
You are doing the same thing, judging if a body is a planet by criteria external to the body (it's slanted orbit), and not characteristics of the body itself.
If Earth's orbit was 'weird and slanted', not on the ecliptic, would Earth stop being a planet? No, of course not.
I don't think that can work. If you pick a random Earth-sized lump of the Sun as a potential planet, and swap its place with Earth, Earth would quickly get mixed in with the rest of the Sun and stop being a distinct entity, so be very silly to still call a planet, and without the Sun's huge gravity to keep it held together, the lump of Sun would spread out into a gas cloud and then just become part of the interplanetary dust. Location makes some difference to whether or not something's a planet.
If you pick a random Earth-sized lump of the Sun as a potential planet, and swap its place with Earth, Earth would quickly get mixed in with the rest of the Sun and stop being a distinct entity, so be very silly to still call a planet,
Why? Everything about Earth is still the same, skies, oceans, etc. Only difference is that it's crowded in by other bodies now.
Trying to scientifically judge if a body is a planet by something external to it, if it's being crowded in our not, it's not logical, and doesn't change the body itself.
What does a body clearing is orbit or not have anything to do with the body itself?
Location makes some difference to whether or not something’s a planet.
Only because a very few human beings astronomers illogically/arbitrarily decided that's so. The reality on the ground for the body is that its still Earth, the planet we live on.
Planetary Scientists should be deciding the rules, and not solely Astronomers.
