Three Science Facts to Impress Your Friends and Teachers

1. Gravity is the invisible force that attracts two objects. The heavier the object, the more gravity it has. Gravity is what keeps the planets in orbit around the sun and keeps all the stuff on Earth from floating into space. The planet called Delta Three that Archie visits in this book is smaller than Earth and weighs less, so it has less gravity. The people who live there are taller, the trees are taller, and it’s easier for birds to fly and people to walk.

2. A wormhole is like a tunnel from one part of outer space to another. Picture an apple—it would take a worm less time to go through a hole in the apple than to go around the skin of the apple. Some scientists believe this kind of a shortcut through space might one day be possible.

3. Even though we don’t think of it this way, our sun is actually a star. It’s just a lot closer to us than any other star. A planet that orbits a star other than our own sun is called an exoplanet. In order for life as we know it to exist, a planet must not be too close to or too far away from its source of heat (its sun) so that its temperature stays within a certain zone. It needs to have water, oxygen, an atmosphere around it, and the right kinds of chemicals in the ground and air. But that’s only life as we know it here on Earth. Other planets could have people or creatures living there that have adapted to their environment as we have adapted to ours. With the help of huge telescopes, astronomers are discovering new exoplanets every day. Someday soon we will surely discover that we are not alone in the vast universe.