A sudden stratospheric warming event reversed the winds that make up the northern polar vortex on March 9. A new animation ...

hoping to better understand the Earth's most extreme environments, some researchers are looking for answers even farther off -- toward the north pole of Mars.

Reaching the North Pole was a fantasy of the ancients. Finding the Northwest Passage was the goal of European explorers. Traversing the Arctic Ocean has become the reality of climate change.