Read these 75 interesting and cool facts about Earth to learn more about our planet. ... The NOAA adds that we—meaning, humans—have only discovered about 20 percent of Earth's waters.

Brush up on your Earth Day knowledge with these interesting Earth Day facts and trivia about how it began and why we celebrate Mother Earth on April 22.

Today, April 22, is Earth Day, a time to appreciate our planet and the two-way relationship we have with it. It’s easy to take Earth for granted, since we see it every day. It becomes—it is ...

Earth Day began in 1970 and takes place on April 22 every year.. Here are 10 questions to test your knowledge of the planet. 1. A day on Earth is 24 hours but it always hasn’t been that way.