Journey back to the beginning of everything: the universe, Earth, and life itself.

This is the incredible story of Trishna and Krishna, twin girls born joined at the head. Abandoned shortly after birth at an orphanage in Bangladesh, they had little chance of survival, until they were saved and taken to Australia by an aid worker. After two years battling for life, the twins are ready for a series of delicate operations that will prepare them for the ultimate challenge.

In October 2007, a striking portrait of a young woman in Renaissance dress made world news headlines. Originally sold nine years before for around $20,000, the portrait is now thought to be an undiscovered masterwork by Leonardo da Vinci worth more than $100 million. How did cutting-edge imaging analysis help tie the portrait to Leonardo?

During World War II, Hitler's scientists developed terrifying new weapons of mass destruction. Alarmed by rumors of advanced rockets and missiles, Allied intelligence recruited a team of brilliant minds from British universities and Hollywood studios to a country house near London. NOVA tells the suspenseful, previously untold story of air photo intelligence that played a vital role.

In 1943 a squadron of Lancaster bombers staged one of the most audacious raids in military history: destroying two gigantic dams in Germany's industrial heartland and cutting the water supply to arms factories. Their secret weapon? A revolutionary bouncing bomb invented by British engineer Barnes Wallis.

Millions of people around the world live in the shadow of active volcanoes. Under constant threat of massive volcanic eruptions, their homes and their lives are daily at risk from these sleeping giants. From Japan's Mount Fuji to the "Sleeping Giant" submerged beneath Naples to the Yellowstone "supervolcano" in the United States, we will travel with scientists from around the world.

In the Rocky Mountains, archeologists uncover a unique fossil site packed with astonishingly well-preserved bones of mammoths, mastodons, and other giant extinct beasts. The discovery opens a highly focused window on the vanished world of the Ice Age in North America.

In 2010, several epic earthquakes delivered one of the worst annual death tolls ever recorded. The deadliest strike, in Haiti, killed more than 200,000 people and reduced homes, hospitals, schools, and the presidential palace to rubble. In exclusive coverage, a NOVA camera crew follows a team of U.S. geologists as they enter Haiti in the immediate aftermath of the tragedy.

Is Antarctica headed for a catastrophic meltdown? New evidence of ancient climate change may hold clues.

Watch as NOVA pieces together clues about a volcanic cataclysm and probes questions about human evolution and Earth's fragile ecosystems. 12/14/2011

"The Fabric of the Cosmos," a four-hour series based on the book by renowned physicist and author Brian Greene, takes us to the frontiers of physics to see how scientists are piecing together the most complete picture yet of space, time, and the universe. With each step, audiences will discover that just beneath the surface of our everyday experience lies a world we'd hardly recognize.

He's been dead for more than 5,000 years and poked, prodded, and probed by scientists for the last 20. Yet í–tzi the Iceman, the famous mummified corpse pulled from a glacier in the Italian Alps, continues to keep many secrets. Now, through an autopsy like none other, scientists will attempt to unravel mysteries about this ancient mummy.

Learn how Peter Higgs' ideas about matter transformed our understanding of space.

Join Brian Greene on a wild ride into the weird realm of quantum physics, which governs the universe on the tiniest of scales. Greene brings quantum mechanics to life in a nightclub like no other, where objects pop in and out of existence, and things over here can affect others over there, instantaneously and without anything crossing the space between them.

Hard as it is to swallow, cutting-edge theories are suggesting that our universe may not be the only universe. Instead, it may be just one of an infinite number of universes that make up the "multiverse." In this show, Brian Greene takes us on a tour of this brave new theory at the frontier of physics, showing what some of these alternate realities might be like.

It separates you from me, one galaxy from the next, and atoms from one another. It is everywhere in the universe. But to most of us, space is nothing, an empty void. Well, it turns out space is not what it seems. From the passenger seat of a New York cab driving near the speed of light, to a pool hall where billiard tables do fantastical things, Brian Greene reveals space as a dynamic fabric.

Time. We waste it, save it, kill it, make it. The world runs on it. Yet ask physicists what time actually is, and the answer might shock you: They have no idea. Even more surprising, the deep sense we have of time passing from present to past may be nothing more than an illusion. How can our understanding of something so familiar be so wrong?

Take a spectacular trip to distant realms of our solar system to discover where secret forms of life may lie hidden. Combining the latest telescope images with dazzling animation, this program immerses audiences in the sights and sounds of alien worlds, while top astrobiologists explain how these places are changing how we think about the potential for life in our solar system.

Scientists want to know if methane gas on Mars is a product of biological processes or a result of geologic activity. To find out, NASA is sending a robotic rover called Curiosity to Mars. This video clip from NOVA's program Finding Life Beyond Earth explores the questions that drive the scientists and the implications of possible findings.

Learn how to find signs of extraterrestrial life in our galaxy without leaving home.