The thing that really pisses me off is that he really plays into the meme that people who believe in God at scientifically illiterate, which isn’t true. Plenty of geologists, astrophysicists, and astronomers believe in God and hold to the scientific theories of the origins of our solar system. But no, old Billy has to go on and on about how tides prove God exists. Fucking douche.
Is the point whether the center of gravity is within one planet?
This doesn’t read that way. It’s a completely arbitrary distinction in any case.
Sure. Just a far far smaller percentage than the scientifically illiterate.
Every system of bodies “rotate about a common fixed point between them.”
A pebble rotating around Jupiter does not orbit the exact center of mass of Jupiter, but a point between the two centers of mass. In that case, it might be a couple of angstroms away from Jupiter’s center of mass, but still technically not at the center of mass.
Earth and Luna’s fixed point resides within the Earth. That makes Luna a true satellite of Earth. Deimos and Mars’ fixed point resides within Mars. That makes Deimos a true satellite of Mars.
Pluto and Charon’s fixed point is NOT inside Pluto. That makes Pluto and Charon two bodies that rotate about a common point, a point not inside either of their bodies.
Yes, that’s the distinction Bricker and I are making.
It might be arbitrary, but it’s PRECISELY the definition found in the IAU’s Draft Resolution 5 for GA-XXVI, Footnote 2:
(emphasis mine)
Done so. But why is it even an issue? As has been noted in this thread, some planets have no satellites, Earth has one, Mars has two, others have several. Sure, Earth is the only one with one, but calling it unique and special is like throwing a die six times and declaring that the fifth throw was unique and special because it was the only one to show a three.
I’m aware, considering that’s what I just said.
I appreciate your continuing to find cites to make my point, It’s quite generous of you.
Quoting form the link you just gave:
OK, so your only point of contention is the distinction of whether the barycenter is below the surface of the planet or not?
Not only is Earth the only planet with only one satellite, but the ratio of mass between Earth and its satellite is orders of magnitude closer than between any other planet. Why is this relevant? Because we’re talking about tides.
Now, Pluto and Charon also have a similar mass ratio, but don’t make the cut because the barycenter of the Pluto-Charon system resides outside either body, making them, by commonly accepted criteria and Resolution 5’s explicit language, NOT an example of a planet and satellite system.
I missed your actual apology, by the way, unless “Done,” was meant to be it… in which case, thank you.
ETA: Damnit, we need to stop editing like this. I knew allowing post-editing was going to be a bad idea someday, just like miniskirts and linotype.
It was better when streetcar fare was just a nickel.
Well, yes it was. Tried to stuff the carbon papers through the internets, but it didn’t work.
You can just fax 'em over.
I thought you were saying that it was unique that the center of one planet was not what was being orbited as well as that the center of mass resides outside Pluto.
We’re on the same page now.
Fun Fact: You can find the center of mass of that piece of paper using the instructions on the website Duke linked to.
Technically, Pluto has three moons.
I’ll be damned. Didn’t know that when I woke up this morning.
Well, at least O’Bill knows that there ARE tides. A fairly significant number of inland tourist don’t seem to know about tides. It was probably taught in the ‘Boring Stuff I’ll Never Use’ part of science class.
They park their cars near the water’s edge and the Pacific eats the car, or they walk out to play on the rocks and have to be rescued by the Coast Guard when the water comes in or they just plain drown in other ways that would be amusing if there weren’t actual lives involved.
There are many warning signs posted about dangerous sneaker waves, etc. but what they really need is a large sign saying “This is not a pond! Where the water line is now is not where it will be an hour from now!”
Or something like that.