After a summer of fasting on land, the bears need to get back to their frozen home to hunt seals and bulk up. But their migration ritual is changing.

Today, we know of Mars as a cold, dry desert, with patches of subterranean ice and ice caps at its poles. Billions of years ...

As Earth approaches warmer levels experienced earlier in its geologic history, it may be bad news for human survival.

Astronomers have identified sulfur as a potentially crucial indicator in narrowing the search for life on other planets. While sulfur itself is not necessarily an indication of habitability, ...