Why is an astronaut like a football player?
They both want touchdowns!

Q. What’s the most popular snack on Mars?

A. Marshmallows.

How do you know that Saturn is married more than once? Because he has lots of rings.

How does Jupiter hold up his trousers? With an asteroid belt.

The Heineken Uncertainty Principle says “You can never be sure how many beers you had last night.”