Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: common_sense_seeker on 16/09/2008 10:19:11

Title: What if the Moon had a moon, and so on?
Post by: common_sense_seeker on 16/09/2008 10:19:11

Imagine that our Moon had it's own moon, and that moon had a moon. How many times could this happen? If the answer isn't "infinite" then what is the limiting factor?

Title: What if the Moon had a moon, and so on?
Post by: lyner on 16/09/2008 13:08:22

For a short while, there have been artificial satellites around the Moon (probes and the manned missions).
The problem with 'moons around moons' is that the larger body - say the Earth - will perturb the orbit of the moon-moon and eventually capture it. The bigger the separation between the Moon and its 'moon', the less likely it is to stay there. If the orbit is very low, then the Earth would perturb it and it could then crash into the Moon.
You could imagine tiny bits of dust orbiting around lumps of rock - like in the rings of Saturn - but there will be collisions and it isn't a stable situation.
At the other end of the scale, the Planets orbit stars and the stars orbit the centre of the Galaxy and the Galaxy's movements are affected by other Galaxies.
Altogether, there aren't many 'layers' of this motion, though - definitely not infinite and more like 5.

Title: What if the Moon had a moon, and so on?
Post by: common_sense_seeker on 16/09/2008 14:00:57

Quote from: sophiecentaur on 16/09/2008 13:08:22

definitely not infinite and more like 5.

Thanks for the first guess.

Title: What if the Moon had a moon, and so on?
Post by: RD on 16/09/2008 22:15:33

Quote from: common_sense_seeker on 16/09/2008 10:19:11

what is the limiting factor?

Would the electron in a hydrogen atom fit your model ? It's orbit is not due to gravity but electrostatic forces.

Title: What if the Moon had a moon, and so on?
Post by: lyner on 16/09/2008 22:25:39

The scale is so small that quantum mechanics comes into it. I don't really think it constitutes a layer for this purpose. It really can't be  treated classically.

Title: What if the Moon had a moon, and so on?
Post by: Make it Lady on 17/09/2008 00:14:34

Your just being greedy with your moons here. It would be like folding a peice of paper in half repeatidly. It would have to become impossible eventually. MOON HOGGER!

Title: What if the Moon had a moon, and so on?
Post by: common_sense_seeker on 17/09/2008 13:06:03

Quote from: Make it  Lady on 17/09/2008 00:14:34

Your just being greedy with your moons here. It would be like folding a peice of paper in half repeatidly. It would have to become impossible eventually. MOON HOGGER!

What do you think the most is in the galaxy? There must be a moon which has the most somewhere. Is it a coincidence that there are no moons with their own moon in our solar system? Maybe it's the same for all solar systems?