Planet Earth

A weird circular shape on Google Earth has ocean-floor UFO hunters crying "alien."

Simultaneous heat waves have hit the Arctic and Antarctica, raising temperatures by more than 50 degrees in parts of both polar regions.

An analysis of rocks exposed to the dinosaur-killing asteroid event reveals that the impact released more sulfur, which led to more global cooling than previously realized.

The first people who migrated to the Americas from Asia may have had to take a circuitous coastal route, as direct passage overland may have been blocked by a massive wall of ice.

Giant "sinkholes" — one of which could devour an entire city block holding six-story buildings — are appearing along the Arctic seafloor.

A tsunami warning has been issued for Fukushima after a powerful 7.3 magnitude earthquake struck the east coast of Japan, according to Japanese government officials.

Antarctic sea-ice extent dropped to a record low in the satellite data in February, but it's likely due to natural variation.

A huge impact crater beneath the ice in Greenland dates back 58 million years, to when the Arctic was green and populated by hippo-like animals.

The central section of the San Andreas Fault usually moves by quietly creeping, but new research suggests it's hosted some serious earthquakes in history.

The oldest known burning fire in the world was likely ignited by lightning at least 5,500 years ago in Australia.

Don't forget to move your clock forward an hour overnight Saturday (March 12), as daylight saving time begins Sunday.

One of Earth's two mysterious mantle blobs is much higher than the other, raising questions about its impact on Earth's surface.

The resulting debris created several dozen craters, the largest nearly 230 feet across.