Looking for a sky event this week? Check out our full Sky This Week column. December 9: Dione and Tethys trade places Neptune is stationary at 7 P.M. EST, ending its retrograde motion. The ice giant ...

Far beyond the bright planets, in the dim outskirts of the Solar System, astronomers keep stumbling on objects that refuse to ...

Scientists have discovered that moonquakes, not meteoroids, are responsible for shifting terrain near the Apollo 17 landing ...

By trapping huge amounts of water on land, big dams built by humans have slightly changed how Earth spins and where its poles ...

Our planet’s magnetosphere has seen dramatic shifts across its history—even total reversals—but this recent wrinkle doesn’t ...

"Some of our ancestors were very skilled observers." A team of international researchers say they've uncovered new data on ...