There is no greater test for life than winter, as temperatures plummet to 70 below and winds reach 200kph. Darkness and ice extend across the polar regions and only a few remarkable survivors gamble on remaining. We join a female polar bear trekking into the Arctic mountains to give birth as the first blizzards arrive. Out on the frozen ocean, the entire world's population of spectacled eider ducks brave the winter in a giant ice hole kept open by ferocious currents. Arctic forests transform into a wonderland of frost and snow - the scene of a desperate and bloody battle between wolf and bison, but also where a remarkable alliance between raven and wolverine is made. Beneath the snow lies a magical world of winter survivors. Here tiny voles dodge the clutches of the great grey owl, but cannot escape the ultimate under-show predator - the least weasel. Midwinter and a male polar bear wanders alone across the dark, empty icescape. Below the snow, polar bear cubs begin life in an icy den while fantastical auroras light the night skies above. In Antarctica, we join male emperor penguins in their darkest hour, battling to protect precious eggs from fierce polar storms. Weddell seals escape to a hidden world of jewel-coloured corals and alien-looking creatures but frozen devastation follows as sinister ice stalactites reach down with deadly effect.

Many argue that flying saucers and other extra-terrestrial space ships continuously visit the earth. If that were true, what kinds of technologies would such alien spacecraft require? And do eyewitness reports of UFO sightings jibe with modern theories of how interstellar travel might be possible? Authors, astronomers and theoretical physicists weigh in with the blueprints for inertia-canceling devices, nuclear-powered craft, antimatter propulsion systems and even warp drives. Based on Einstein's theories and countless scientific studies, we'll find out how these visitors might bridge the vast distances between the stars. And if they could survive such hazardous journeys, are they flesh and blood or intelligent machines?

Every year, thousands of aspiring dancers enter one of the world's most prestigious ballet competitions, the Youth America Grand Prix, where lifelong dreams are at stake. In the final round, with hundreds competing for only a handful of elite scholarships and contracts, practice and discipline are paramount, and nothing short of perfection is expected. Bess Kargman's award-winning documentary, First Position, follows six young dancers as they prepare for a chance to enter the world of professional ballet, struggling through bloodied feet, near exhaustion and debilitating injuries, all while navigating the drama of adolescence. A showcase of awe-inspiring talent, tenacity and passion, First Position paints a thrilling and moving portrait of the most gifted young ballet stars of tomorrow.

For the first time, you will see dramatic moments of WWII that were captured in 3D with stereographs and then shuttered away in secret archives and attics, until now. This stunning collection of colour 3D photos includes Allied reconnaissance photos, a trove of images that documents the rise and fall of the Third Reich, and photos secretly taken by a civilian in occupied France. WWII IN 3D also features an actual 3D motion picture film shot by the Nazis in 1943 and creates a fully immersive, three dimensional portrait of history's largest and bloodiest conflict.

In the fourth part of the series, Diarmaid MacCulloch makes sense of the Reformation, and of how a faith based on obedience and authority gave birth to one based on individual conscience. He shows how Martin Luther wrote hymns to teach people the message of the Bible, and how a tasty sausage became the rallying cry for Swiss Reformer Ulrich Zwingli to tear down statues of saints, allow married clergy and deny that communion bread and wine were the body and blood of Christ.

American troops launch widespread 'search and destroy' operations; body count, not territory, becomes the measure of success in Vietnam. Charles Brown fights for survival on the bloody slopes of Hill 875 and at home, the American public begins to question U.S. military strategy.