bullet on the moon

[matthay]

is it true that if you stand on the moon and fire a gun, the gravitational pull or lack of it will mean that the bullet will eventually be prepelled around the circumrance of the moon's surface and shoot the shooter in the back

[rojash]

No

[fo3nix]

If you fire it fast enough, and from a high enough point, then yes. But otherwise, as rojash says, no.

Incidentally, the same applies to Earth. Neglecting the atmosphere of course ;)

[rojash]

The lower the gravity, the lower the escape velocity, so by the time you get to a point where your bullet could make it all the way round without falling to the ground, it won't in go round, but will in fact go shooting off into space.

[mibn2cweus]

Although high speed bullets nearly reach the 1683 m/s velocity required for a near lunar orbit, the precision required to hit a human size target at over 10000 km (lunar equatorial circumference = 10920 km) is astronomical.

If an orbit around the Moon were achievable, (after traveling one hour and 48 minutes in a complete circle), variations in the Moons mass density would cause enough deviation in its trajectory that travel back to the same point of origin would be nearly impossible. In addition the Moon would have rotated 30 km at the lunar equator in the time required for the bullets trip, so your best (or worst) bet would be to shot straight along the equator (from the highest point) or in a slightly elliptical orbit from the axis of rotation (since the equatorial radius is slightly greater).

Even so, I don�t think I would care to take a trip to the Moon for the purpose of attempting to use my own back-side for target practice. But then you would have plenty of time to move out of (or in?) the way. Or if you�re feeling particularly lucky you could turn 180 degrees and step on a stool. Yikes!

[heathfield]

In short, mibn2cweus, though unlikely, the answer is still a "Yes"?

[mibn2cweus]

Hey, what the hey, give it a shot. From the highest point gravity would be slightly less and a well designed bullet could achieve orbital velocity, although you are probably more likely to get hit by a meteoric particle before you succeeded in a self inflicted gun shot wound.

Just don't use to much powder. Escape velocity is only about 40% faster and murder is still a capital offence in some countries. Execution squads rarely miss!

I'm offering a million lbs. to the first person to fire a bullet that manages to orbit the Moon twice before striking the surface. I don't have the cash yet but my chances of winning the lottery are much more likely.

[john91]

at the other extreme, if you could stand on a planet with a strong enough force of gravity, you should be able to see the back of your head.

[whowhatwhy]

okay john91...WHAT?!

[john91]

light is bent by gravity, so if an object has a powerful enough force of gravity, light would just continue to revolve around it, so if you stood on this planet ( with difficulty ) the light from the back of your head instead of shooting off into space as it does on Earth, would revolve around the planet for you to see it.

[boobesque]

i dont think that the bullet would fire on the moon. but you would get a few groovy clicks that you cant hear