It is said that Mars is Earth's sister planet. Next to Earth, it is the most habitable planet in the solar system because it is neither too hot nor too cold. It

It is said that Mars is Earth’s sister planet. Next to Earth, it is the most habitable planet in the solar system because it is neither too hot nor too cold.

Laugh and learn with fun facts about the sun, the moon, the planets, constellations, astronauts, and more—all told in Dr. Seuss’s beloved rhyming style and

The Apollo 11 astronaut invites young people to evaluate Mars as a potential planet for human colonization, and describes what Mars residents might experience w

Since the dawn of humankind, people have looked upward to the heavens and tried to understand them. This encyclopedia takes you on an expedition through time an