A wide open space (It could be your backyard or a park.) Two Hula-Hoops (Alternatively, you could use two flat rocks or bricks that you can sit on.) A yardstick or meterstick (Use one that has clear ...

The universe is so vast that even the closest stars are light-years away. They are so distant that they were long thought to be fixed points in the velvet night. Since we can't yet travel to the stars ...

Try this experiment: extend your thumb at arm’s length and close one eye at a time. Your thumb will seem to ‘jump’ between two positions as you switch the eye that is closed. That jump is known as ...