1
$\begingroup$

Would the Moon really only travel in a straight line then? What about the other planets and their forces of gravity? Wouldn't they prevent this rectilinear and undisturbed motion of the Moon?

$\endgroup$
  • $\begingroup$ There is no such thing as a centripetal force. There is something called centripetal acceleration, which just describes a very specific type of acceleration, namely that of circular curves. The only macroscopic forces present in the Earth-moon system are gravity, radiation pressure (very weak), and particle pressure (almost non-existent from dust and solar wind particles). $\endgroup$ – honeste_vivere Jul 25 '18 at 14:07
4
$\begingroup$

If the Earth just disappeared, the Moon would continue around the Sun on pretty much the same path it has now.

To see this, consider the velocity of the Earth/Moon system around the Sun:

$2\pi \times 150 \times 10^6 \text{ km} / 365 \text{ days} = 2.6 \times 10^6 \text{ km}/\text{day}$

versus the Moon's speed around the Earth:

$2\pi \times 385 \times 10^3 \text{ km} / 29 \text{ days} = 83 \times 10^3 \text{ km}/\text{day}$

The motion around the Sun is a factor of $30$ faster; the Moon's motion around the Earth is just a small perturbation on that.

| cite | improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.