Montezuma Dan Snow journeys to the ancient heart of Mexico in search of the lost civilisation of the Aztecs and their last and greatest ruler, Montezuma II (1502-1520). Montezuma inherited an empire of five million people, stretching from present-day Mexico to Nicaragua, from his uncle. His rule was marked by incessant warfare. Enemy states were growing more powerful and conquered tribes were becoming more rebellious. Within months of taking the throne in 1502, he went changed a man of good reason into a pitiless autocrat who declared himself a god, believing that fear and ruthlessness were the only ways to stop the empire falling apart. Yet it was at the hands of Cortes and the Spanish conquistadors that Montezuma met his downfall. But what was his relationship with Cortes, and why did such a ruthless leader submit to his captors with such relative ease? As Dan Snow visits the ruins and picks through current excavations, he pieces together the evidence of a gripping story: a divine tragedy of errors, the clash of civilisations, the end of a world - and a very human God.

Caravaggio's approach to painting was unconventional. He avoided the standard method of making copies of old sculptures and instead took the more direct approach of painting directly onto canvas without drawing first. He also used people from the street as his models. His dramatic painting was enhanced with intense and theatrical lighting. Caravaggio's fate was sealed when he killed a man in a duel in 1606. He fled to Naples where he attempted to paint his way out of trouble, he became a Knight, but was then imprisoned in Malta and then finally moved to Sicily. He was pardoned for murder in 1610, but died of a fever when attempting to return to Rome. For me the power of Caravaggio's art is the power of truth, not least the truth about ourselves. If we are ever to hope for redemption we have to start from the recognition that the Goliath competes with the David in all of us."

A constellation is a group of stars that are connected together to form a figure or picture. Explore some of the 88 official constellations and learn about some of the highlights of each.

Professor Brian Cox travels from the fossils of the Burgess Shale to the sands of the oldest desert in the world to show how light holds the key to our understanding of the whole universe, including our own deepest origins. To understand how light holds the key to the story of the universe; you first have to understand its peculiar properties. Brian considers how the properties of light that lend colour to desert sands and the spectrum of a rainbow can lead to profound insights into the history and evolution of our universe. Finally, with some of the world's most fascinating fossils in hand, Brian considers how but for an apparently obscure moment in the early evolutionary history of life, all the secrets of light may have remained hidden. Because although the universe is bathed in light that carries extraordinary amounts of information about where we come from, it would have remained invisible without a crucial evolutionary development that allowed us to see. Only because of that development can we now observe, capture and contemplate the incredible wonders of the universe that we inhabit.

The very heart of Africa is covered in dense tropical rainforest. The animals that live here find the most ingenious ways to carve out their space in a claustrophobic landscape. Danger lurks in every shadow, but some animals thrive here, from honey-stealing chimps to birds with a lineage as old as the dinosaurs, thundering elephants and kick-boxing frogs. Here in the Congo, no matter how tough the competition, you must stand up and fight for yourself and your patch.

'Dinosaurs: Giants of Patagonia' Following Pr Rodolfo Coria, a world-reknown Argentinian paleontologist, we visit sites of major discoveries he has contributed to in Patagonia and travel back in time to see these amazing beasts come to life in 3D. Patagonia has given us the largest living animal to ever walk the Earth: the titanesque plant-eating Argentinosaur, and its nemesis, the Giganotosaur, a bipedal carnivore that could easily challenge the famous T-Rex.