lava

The moon may be a harsh mistress, but lately she has been giving up her secrets. Scientists have spotted a deep hole in the lunar surface that goes at least 260 feet down and is believed to open into an underground tunnel more than 1,200 feet wide.

The discovery is powerful evidence for long, winding tunnels carved by lava beneath the lunar surface. Such tunnels, whose existence has long been hypothesized, could provide shelter for future astronauts or colonists against the harsh radiation and surface temperatures on the moon.

Volcanic eruptions have altered global climate, and the global landscape, throughout history. In this new gallery, PopSci.com gives these ecological blockbusters their due.

At 10:38 p.m. last night, Alaska's Mt. Redoubt made its first of five eruptions, the last blowing at 4:31 a.m., sending a cloud of volcanic ash 60,000 feet above sea level, according to the National Weather Service.