274
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 05 Oct 2024
274 points (93.1% liked)
Showerthoughts
29816 readers
97 users here now
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. A showerthought should offer a unique perspective on an ordinary part of life.
Rules
- All posts must be showerthoughts
- The entire showerthought must be in the title
- Avoid politics
- 3.1) NEW RULE as of 5 Nov 2024, trying it out
- 3.2) Political posts often end up being circle jerks (not offering unique perspective) or enflaming (too much work for mods).
- 3.3) Try c/politicaldiscussion, volunteer as a mod here, or start your own community.
- Posts must be original/unique
- Adhere to Lemmy's Code of Conduct
founded 1 year ago
MODERATORS
If Pluto is a planet, then Ceres is a planet too. CERES RIGHTS!
Let's just acknowledge that anything big enough to be round is a planet. That's the bare minimum criteria.
Orbit shapes and clear paths don't matter, the Solar system isn't a typical stellar system, many aren't so stable and ordered, especially in binary and triplet star systems. So the pedantry around the shapes of the orbits of the outer kuiper planets is a very silly thing to argue about. After all most orbits in binary and triplet systems aren't even predictable long term, let alone not circular.
So that makes Earth and Moon a binary planet system. I'm cool with that
I believe the rule of thumb is binary planets' barycentre is external to either body. This is the case with Pluto/Charon, ~~I think it's also the case with Earth/Moon.~~
It is not the case with the earth and the moon. It would be if the moon was 40% more massive
Yeah, I went and checked after posting.
My hunch is that if the moon was closer it would 'drag' the barycentre closer to the moon.
Which, given the moon is slowly receeding, means it was probably a binary early on in the formation of the solar system.
Other way around, the further apart the objects are the less likely the barycentre is to be inside one of them, you can picture it as a rubber band with a dot drawn on it, the more you stretch it the further the dot gets from both ends even if it gets further from one end faster.
Nice analogy.
TYVM!
That's a good rule of thumb... but it's probably not enough; no reasonable definition would call Jupiter a star, or even a brown dwarf, or the Solar System a binary system, yet the Sol - Jupiter barycentre is outside the sun... (the whole system's barycentre is sometimes inside the sun, but that's due to Saturn's, Uranus', and Neptune's pulls cancelling Jupiter's).
I'd call the barycentre thing a necessary but not sufficient requirement; a proper definition of double planet should probably also take into account other factors like the relative mass and density of the bodies, and their minimum and maximum distance.
OK, can you name all planets in the solar system?
Sure. Jeff, Darryl, Norma, Luanne, I got lotsa names.
Remember the Cant!