Please forgive my ignorance.
In the movie Apollo 13, the astronauts seem to be weightless the whole time that are in space. Why is this? I thought astronauts only appeared weightless because they were in orbit. Why did they appear weightless the whole time?
I’m under the impression that there is much less gravity in space than on earth(duh…wow, I’m stating the obvious here…keep reading, I’m not as dumb as I probably sound;)), and that is the case inside of the spaceships, as well.
Either that or it’s Hollywood exagerating, because it makes a better movie.
**Jamie
For you and I, the strongest source of gravity is the Earth. As you move farther away from the center of the Earth, your weight decreases because you don’t feel the pull of the Earth as strongly. By the time you get out of the atmosphere, you’re pretty much weightless, and that stays true as you get further out into space - after all, being in orbit IS being in space. So yes, it’s correct that the astronauts stay weightless.
Far enough away from the earth’s gravity – yes, there is weightlessness in space.
Apollo 13 didn’t have a fancy artificial gravity generator at the time, so …
When you’re in space and the engines are off, you are in orbit, or free fall. In case of the Apollo, after launch it goes into a low earth orbit, more or less circular. Then an engine is fired briefly to move the spacecraft into a different orbit, a highly elliptical one whose apogee (highest point of orbit) is near the moon. It’s still an orbit, so the spacecraft simply coasts along it till it reaches the vicinity of the moon. An engine is fired again to put it in a yet another orbit, namely a circular one that goes around the moon.
Or did you mean how they filmed the weightless scenes? IIRC many of the scenes were shot in a training aircraft which simulates free fall. It flies in a parabolic trajectory that approximates the motion of free fall.
Although I cannot speak as authoritatively as some of the physics gurus on this board, I’ll fill in a bit 'til they get here.
Nope, on all accounts. Astronauts are not weightless because they are away from Earth’s gravity. The pull of gravity decreases with the distance to the center of Earth’s mass (I believe that it’s an inverse ratio to the square of the distance). Since the earth has a radius of just under 3000 miles and low Earth orbit is only a couple hundred miles up, the affect of gravity is not that much less in orbit than it is on the surface of the Earth.
In the case of the astronauts in orbit, they are in free fall. They are not outside the pull of Earth’s gravity, they simply are no longer fighting it. As gravity pulls them down, they also have a horizontal vector that means that as they fall down, they also move horizontally so that they are constantly falling around the planet.
In the case of moon shots, if I’m correct (and if I’m not, I’m sure someone will be along to correct me) they are still in orbit, just a very elongated one that, at its apogee, took them around the moon.
Just as an aside, a good portion of the weightlessness in the movie Apollo 13 was not faked. The producers arranged the use of the training plane that NASA uses (delightfully nicknamed the Vomit Comet) in order to create short periods of real weightlessness with multiple parabolic flights.
Err, make that nope on all counts to everyone but scr4.
Way to be LVP :). You can be weightless anyplace, so long as you stop counteracting gravity. Skydiving would seem to be the easiest way for you to experience it yourself, though jumping off your roof is a similar, if shortened experience. 
P.S. - In case we’re misunderstanding your question, when might they not appear weightless, and in which direction would they be pulled?