Photo courtesy NASA

Have you ever seen the videos from NASA where the astronauts are floating in weightlessness? They can do somersaults in mid-air, "swim" through passageways, and drink from "balls" of water that are floating in the air. The whole thing looks incredibly fun.

Let's say that you would like to go into space and have a weightless experience. Even if you're not an astronaut, there's still a way to do it. There is one little problem, though -- space travel is incredibly expensive right now. Russia charges about $20 million for "space tourists" to ride into space and stay at the space station for a few days.

If you don't have $20 million, what can you do? The next best thing is to fly on an airplane that lets you experience weightlessness during the flight. NASA has a Reduced Gravity Research Program that flies these kinds of airplanes. Several other companies possess similar technology - and they're sharing it, for a fee, with adventurous people.

So, how does an airplane flying throughout the air create the effect of weightlessness? Let's find out.