What water craft relies on the horizontal push from the downward pull of gravity to move? Find out on this Moment of Science.
Contrary to what fairy tales tell us, there is nothing holding the moon up in the sky. So why doesn't it fall down? Find out on this Moment of Science.
You can see this more easily by imagining what would happen if the earth were flat. The moon would still travel in a horizontal line above the ground; but because it’s also falling, it would come closer and closer to the flat earth until it collided.