Meteor

What Is a Meteor Shower?

What causes them?

Asteroid or Meteor: What's the Difference?

Learn more about asteroids, meteors, meteoroids, meteorites, and comets!

Mesosphere

The middle layer

Glossary

Find definitions of space and Earth science terms

What Are Constellations?

Learn more about what these groups of stars can (and can’t) tell us about our place in the universe.

What Is a Gravitational Wave?

How do gravitational waves give us a new way to learn about the universe?

Why Does the Moon Have Craters?

It's not because the Moon gets hit by meteors more often...

What Is an Earthquake?

Learn more about tremors on Earth—and other planets too!

What Is a Supernova?

Learn more about these exploding stars!

What Is an Impact Crater?

Learn about impact craters!