We all know Mars is called “The Red Planet,” but have you ever stopped to wonder—why is it red? The classic joke explanation ...

The first life forms used retinal instead of chlorophyll, absorbing green light and reflecting red and blue—turning the planet an eerie purple. Chlorophyll wasn’t always king. Retinal ...

Watch this video to find out more about the Earth, planets in our Solar System and other planets far off in outer space. From up here on the International Space Station I get a great view of Earth.

"It's a really exciting find—Barnard's Star is our ... of each planet tugs slightly on the star's position, meaning the star seems to wobble back and forth. MAROON-X measures the color of ...