Isn't that true for all moons, though, simply because the radius of the orbit around the sun is much larger than the radius of the moon around the planet?
also, isn't the force ratio issue more an issue of the inverse square law than anything else?
also, isn't the force ratio issue more an issue of the inverse square law than anything else?
That still wouldn't make the Moon a planet though.
the earth goes around the sun at 29 785.8944 mps, so for a satellite to appear to stand still (from the sun's perspective) it needs that orbital speed (i'm assuming that everything orbits in the same plane to make things easier/cleaner).
using the equation v^2 = GM/R gives an orbital radius of(G = 6.673 x 10^-11 N m^2/kg^2 and M = 5.98x10^24 kg, 1N = 1kg * 1m /1s) 449, 777 m or 449.7 km. Of course, the radius of the earth is 6.3 million meters (6300 km), so this isn't exactly possible.
the only way for a satellite orbiting a planet to appear to move backwards with respect to the thing the planet orbits is for the satellite to have a faster orbital velocity than the planet's orbital velocity.
If the same happened to Jupiter, all of those moons would fly out of of the solar system. (Or at least go cometary.) None of the orbits would survive.
The orbital velocity of Earth is the escape velocity of the solar system, from Earth (42.1 km/s). Fun fact, this means that if we ever wanted to dispose of nuclear waste by dumping it in a star, we'd need much less rocket fuel to hit Alpha Centauri than the Sun.
It'd be interesting to see what happens at Jupiter's orbit, thouh. Does Io always leave? What about Callisto? It seems like there would be a large part of their orbit that would send them off into cometary orbits (or worse) depending on what direction they are going when scotty beams jupiter aboard the enterprise.
Edit: http://en.wikipedia.org/wiki/Escape_velocity To escape from the suns orbit at Jupiter's distance from the sun takes 18.5 km/s vs Mars orbit's 34.1 km/s, or the Earth's orbit 42.1 km/s.
PS: The moon was the original example of 'moon' so it's a moon by definition. Any definition that does not include it must be describing something other than a 'moon'.
PS, The Earth was the original example of 'flat' and nothing is ever allowed to change as we gain better understanding.
PS: The Earth is not the original definition of flat.
However, when you look at the actual accelerations involved the moon is much more attracted to the earth (by over 100x) than it is to the sun or the center of the Galaxy. Which is why the moon is tidally locked with the earth and not the sun.
PS: All of these still don't add up to the 583km/s velocity relative to the CBR.
Your "over 100x" figure is entirely made up. The correct answer is 0.46.
Depth of the well does not matter, it is the steepness of the well. In other words, what is pulling the hardest on the Moon. The Sun pulls twice as hard as the Earth, so there is a compelling argument that the Sun is the Moon's primary.
The black hole at the center of the Milky Way is (rounding up for your benefit) 4 million solar masses and 27000 ly away. But that inverse square law really hurts and the Sun's gravitational force is 733e15 times stronger than the black hole's.
Let's step it up and include all 10 billion solar masses in the center. The Sun is still ahead by a factor of 290 trillion. The galactic core has almost no effect on the solar system, so it is silly to claim that any planetary body orbits the core.
Regarding tidal lock, the force of tidal lock is (more or less) proportionate to gravitational force * angular velocity. While the Earth's gravitational force on the Moon is half as strong as the Sun's, the relative angular velocity is 12 times faster. So the Earth's tidal forces on the Moon are six times stronger than those of the Sun. Naturally, the Moon is tidal locked to the Earth.
the period and orbital velocity are dependent on the mass of the orbited object and the radius of the orbit.