A mysterious crash in Roswell, NM during the 1940s convinced many that our planet is being visited by space aliens. Crop circles in Britain have only added fuel to the fire. Few scientists doubt that life indeed exists elsewhere, but some believe we're more likely to make contact via radio waves.

Several possible reasons for the Triangle's reputation as a danger zone are investigated. Scientists have discovered that the area's magnetic field has dropped considerably in the last 20 years. Could activity involving underwater volcanic vents be affecting the field and posing a threat to vessels? UFO's, as well as bizarre weather conditions, are also considered as possible explanations.

Some of the worst nature can offer is spawned from the skies above. Though their damage is concentrated, a tornado's strong winds can turn debris into deadly missiles. With hurricanes, a huge amount of energy is discharged over hundreds of miles causing widespread devastation. What are the precautions can we take to protect ourselves?

The general belief is that Druids built the ancient circle of stones. Recent archeological discoveries and new technologies reveal Stonehenge to have been built long before Druids arrived. Did the technology to build such a structure exist 4000 years ago?

National Geographic Naked Science presents "Super Volcano", the inside documentary of what might happen if the Yellowstone Caldera were to erupt one day. This documentary includes a Yellowstone timeline of past eruptions, how Yellowstone would affect the world, and what impact will it be for the U.S.

An untold number of asteroids have slammed into Earth over millions of years. Scientists are now monitoring the skies watching for the next 'big one', and considering options on how to prevent the next major impact.

The science of earthquakes is examined in this episode. Archival footage highlights damage from the great 1906 quake in San Francisco, as well as 1964's deadly quake in Alaska. Despite efforts to 'quake-proof' bulidings, some simply don't survive; why this happens is explained. Also discussed are tsunamis, caused by undersea earthquakes, and the threat they pose to coasts worldwide. Efforts by scientists to predict earthquakes are also investigated.

Experts compare the deadliness of bull, white, and tiger sharks, as well as profile their biology and behavior. The cause of shark attacks and what can be done to prevent them is discussed. Since sharks generally cover territories of several hundreds of miles, efforts to rid them from particular beaches are usually unsucessful. Sharks also use their mouths to examine their surroundings and determine what is and isn't food, leading to many shark attacks against humans.

In 350 B.C. Plato wrote about an ancient civilization that disappeared in one day in a catastrophic event. Is the story simply a myth or have remains of a real Atlantis been discovered? This episode examines the city that Plato described and analyzes a four leading sites that present-day explorers believe could be the remains of the ancient city.

The story of human evolution traces the development of our species from our earliest ancestors through their mastery of tools and their environment. Through five million years, the essence of what it means to be human is analyzed.