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.

On the second part of his journey through the dark ages Richard Rudgley continues into the age of the wandering peoples, the Volkerwanderung. These Northern people enjoyed a golden age unaffected by Rome and just 30 years after the Romans relinquished Britain, the 'Anglo-Saxons' made their move. The bedraggled legions are in retreat. Walls are pulled down. Mosaics shattered. And yet there never was a people called Anglo-Saxon. We look at the lasting influence of Saxon leaders like Alfred the Great, and his blue print for social justice.

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 II abdicates, and civil war erupts. In May 1918, a year after the revolution, the Bolsheviks sent Anastasia, Alexei, Tatiana and Olga to join the rest of the family in Ekaterinburg. They're put in the Ipatiev mansion and It's given the name 'The House of Special Purpose.' As pro-royalist forces close in on the house where the Romanovs are imprisoned, the family's fate is sealed.

David Attenborough reveals the extraordinary ways that some animals use colour to hide and disappear into the background. New science reveals how the Bengal tiger in central India uses its orange-black stripes to hide from its colour-blind prey. In Kenya’s Masai Mara, the zebra’s black-and-white pattern confuses predators with an extraordinary effect called motion dazzle. And on the island of Cuba, a small snail uses colourful stripes in a surprising way to hide from its enemies.
Other animals use colour to trick and to deceive. On Australia’s Great Barrier Reef, a blue-striped blenny uses colours to mimic other fish and launch a sudden attack. In the grasslands of Zambia, the chick of a pin-tailed whydah mimics the patterns of its nest mates to ensure that it is not detected as an imposter. And specialist cameras reveal how a tiny crab spider uses bright ultraviolet colours to lure in its victims.

In the last episode, despite disturbing revelations of wrongdoing at Three Mile Island before and after the accident, the utility fights to bring the plant back online. Its Unit 1 had its license temporarily suspended following the incident at Unit 2. Although the citizens of the three counties surrounding the site voted by an overwhelming margin to retire Unit 1 permanently in a non-binding resolution in 1982, it was permitted to resume operations in 1985 following a 4–1 vote by the Nuclear Regulatory Commission.
In 2017, it was announced that operations would cease by 2019 due to financial pressure from cheap natural gas, unless lawmakers stepped in to keep it open. Unit 1 shut down on September 20, 2019.
Billed as the worst nuclear incident in U.S. history, what’s particularly scary here is how close Three Mile Island incident came to becoming a national disaster. Without giving away the whole story, cost-cutting 'solutions' almost cause a catastrophic disaster.