Many people believe that there is no gravity in space, which is why astronauts appear weightless in a space craft or space station. The truth is a bit more complicated than that though.
Why does it seem astronauts are weightless in space? To be clear, there is absolutely gravity outside of Earth. In fact, it’s the Earth’s gravity that holds the moon in constant orbit. Distance makes it weaker, but doesn’t stop it. Earth’s gravity pulls on stars, planets and even galaxies. Why, then, do astronauts appear as though they’re defying gravity? The contents of the universe are essentially in constant freefall. Think about when you get in an elevator that goes down. Don’t you feel a bit lighter? However, with no air resistance in space, it takes less momentum to get moving. Although gravity still exists on, say, the moon, it isn’t as strong. Astronauts who jump on the moon go much higher, without air resistance getting in the way, and also have less gravity pulling them back down. The result is that they appear to be weightless.