Astronauts aboard the International Space Station (ISS) have long used the seeming weightlessness of space to have a bit of fun — chasing their dinner through the air, playing tug-of-war and mimicking superheroes. But is there a traditional "up" and "down" in space? Based on the astronauts' experiences, it's easy to think that the usual designations we use to define our positions, such as up and down or North and South, no longer apply once we leave Earth.
