Looks at the scientists striving to understand the forces at work behind last year's tornado outbreak. Could their work improve tornado prediction in the future? Nova also talks to people whose lives have been upended by these extreme weather events in an effort to learn how we all can protect ourselves and our communities for the future.

Join astrophysicist and novelist Janna Levin on a mind-blowing voyage to the frontiers of black hole science, which is shining new light on the most powerful and mysterious objects in the universe.

The largest masonry dome on earth, Florence's cathedral of Santa Maria del Fiore, is a masterpiece of ingenuity and a source of mystery. Historians and engineers have long debated how its architect, kept the dome perfectly aligned and symmetrical as the sides rose and converged toward the center. To test the latest theories, a team of U.S. bricklayers will help build an experimental, mini-Duomo, using period tools and techniques.

Tells the story of what happened in the Vietnamese village My Lai on March 16, 1968, drawing on recently discovered audio recordings and new interviews with participants, eye witnesses, and investigators.

This riveting special investigates a new image of the Vikings that goes far deeper than their savage stereotype as raiding marauders. They were expert shipbuilders, superb artisans, canny merchants, and bold colonizers

George Washington, was a social climber, land-hungry Virginia surveyor, and military officer who often blamed others for his own errors. He gradually built a reputation as a gentleman by educating himself in the classics and sciences, entering politics, and marrying one of the wealthiest women in Virginia. The battle of Trenton changed everything with a victory both for America and Washington himself. His skill and bravery transformed Washington into...

Join the race against time as art and restoration experts mix history, science and politics in a complicated and daunting mission to preserve Mustang's religious works of art.

Arthur chronicles the adventures of the world's most famous aardvark, eight-year-old Arthur Read, and his family and friends. Includes: Hic or Treat; Mr. Alwaysright; Francine's Pilfered Paper; and Buster Gets Real.

[v.4. We have a plan]: The story of socialist author Upton Sinclair's 1934 run for governor of California is told. Sinclair's epic plan to end poverty in California called for seizing unused factories and fields (and film studios) and turning them over to the unemployed to run as self-managing cooperatives. Sinclair won the Democratic nomination and received 900,000 votes against the Republican incumbent. In the process he scared the pants off California's...

Four and a half billion years ago, how did life emerge on Earth? Robert Hazen advances a startling idea, that the rocks on Earth were not only essential to jump-starting life, but then, life helped give birth to hundreds of minerals we rely upon today.