Happy Earth Day. Our planet is the only one in our solar system not named for a Greek or Roman god. At the risk of sounding flip, the name Earth comes from… earth.
Our planet is sometimes called the big blue marble, but there's a hypothesis that suggests if you look way back in time, Earth may have once been bright purple.
We’re hearing a lot about how a research project has shown that Earth days used to be about a half-hour shorter than they are now. Why is our planet rotating more slowly now? It's mostly because of the moon.
