Secrets of the Earth

Episode 2

Tsunamis

Tsunamis form in the open ocean before making toward land. Science seeks not only to understand these giant waves but also predict them.

Episode 3

Gravity

Earthquakes can actually affect Earth's gravity, and the ability of scientists to map gravitational fiels has uncovered mysterious anomalies.

Episode 4

Goldilocks

Earth's distance from the sun is just right to sustain life, with neighbors Venus and Mars illustrating the impact of a slight difference in location.

Episode 5

Magnetic Shield

A metallic core at the center of the Earth turns the planet into a magnet, generating a field that protects life on the surface from cosmic radiation.

Episode 6

Blizzards

A visit to the researchers at a Colorado storm lab and an examination of lake-effect snow in northern New York reveal the science of blizzards.

Episode 7

Tides

Water levels rise up to 50 feet at high tide in Canada's Bay of Fundy, while the Turnagain Arm in Alaska experiences 10-foot-high tidal "bore waves."

Episode 8

Volcanoes

As evidenced by the 1815 eruption of Indonesia Mt. Tambora, volcanoes can profoundly impact the weather, producing lightning, ash and acid rain.

Episode 9

Strangest Places

The world's most astonishing sites include extreme underwater ecosystems, steamy subterranean worlds and stratling igneous formations of lava rock.