Imagine floating through the air, standing on the ceiling, or leaping upstairs in one big bound! An astronaut traveling through space can do all of these things. But on the earth, you can't. You...
The big, blue marble
The earth looks like a big, blue marble to astronauts flying in outer space. It's easy for them to see the round shape of the earth because the astronauts are so far away. But how can you see the...