What sort of alien civilizations might exist in the vastness of space? Terra is the fictional world imagined in Episode 4, a planet nine billion years old, twice as old as Earth. Old enough that a truly advanced intelligence could evolve. It was once a fertile world, now it is barren. But life can still thrive here in artificial domes. Over time, they've evolved not to need their bodies. They exist only as neural tissue. They never age, they never die. They're monitored and maintained by robots.
If alien civilizations are statistically so likely, why haven't astronomers found any sign of them? Where is everyone? Every time we look at an individual star, that's like dropping a bucket in the ocean. We're going to have to look at a lot of stars and to search through a lot of data until we find the clue that leads us to another civilization.

Each night, across the planet, our cities illuminate the darkness. Their lights burning brighter than ever before. And whilst we're asleep, animals are making the most of this new neon landscape. The sunset in Los Angeles, Chicago, and Toronto creates worlds of opportunities for the cleverest animals willing to take the risk.

The great mountain ranges are some of the planet's most spectacular landscapes, but they are unforgiving places to live in, and only a few animals have what it takes to live at extreme altitude. Mountain animals are amongst the most elusive in the world, and this film provides unique and intimate glimpses into their secretive lives. Witness the moment four snow leopards come together when a mother and cub become trapped between two rival males. Join grizzly bears as they dance against trees to rub off their winter fur and soar with golden eagles hunting amongst Europe's snow-capped peaks.

The third assault on the tattered remains of Roman civilization came from even further North, where the melting glacial ice had created immense sheltered fjords, leaving its inhabitants little choice but the sea. These fearless navigators understood that dominion over the oceans was the key to their ambitions.
Where the Romans expanded incrementally, the Vikings adopted a bolder, more aggressive approach. So was it the Dark Age which failed Europe, or the stifling uniformity of the great Roman experiment? Were the lost tribes more victim than failure? Richard Rudgley will hope to shed new light on the real secrets of the so-called Dark Age.

Nicholas felt enormous pressure to continue the dynasty and expand the empire. He saw his opportunity in the Far East. This brought him into conflict with a rising power, Japan. Russia's disastrous war against Japan prompts civil unrest. The birth of Prince Alexei is incredibly important. He's the long-awaited son that they had hoped so much for. But when Alexei is diagnosed with haemophilia, Siberian mystic Rasputin steps in. He's very good at realizing when something is open that will enable him to increase his power and wealth. The pressure of keeping the secret of Alexei's illness affects the political decisions that Nicky and Alix made for the rest of their reign.

A Japanese playing card company called Nintendo enters gaming. To stay competitive in a modernizing Japan, their portfolio expanded to include toys and into the arcade. And the company hit it big with Donkey Kong and Super Mario, then later takes over home gaming with the Nintendo Entertainment System.