Most planets we know of are so hellish, it seems impossible that anything could live. But it's amazing where life can take hold in the Earth. Astrobiologists look for simple single-celled microbes known as extremophiles in places as Danakil Depression, known in Ethiopia as 'The Gateway to Hell.'
In Episode 2, the fictional world is Janus, a planet in such a close orbit than its rotation is locked by the star's gravity and it always shows the same face to its sun. On one side of the planet, it's always daytime, a searing desert. On the other side, it's forever night, a frozen shadowland. Squeezed between the two, a sliver of perpetual twilight. Freezing meltwater flows from the cold side, carving canyons through the landscape. Deep in these canyons lives an extraordinary five-legged creature.

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.

After four decades of searching for him, they got a one hundred percent match to the Golden State Killer's DNA. As 72-year-old former police officer Joe DeAngelo's arrest unfolds in real time, chilling facts materialize that illuminate Michelle McNamara's prescience in her book's epilogue.

One extraordinary family of fish has achieved the ultimate form of gender equality. When it comes to breeding, seahorses do it like no other animal on the planet. Their fierce females refuse to be left holding the baby. So it's the males that carry their brood. In this episode we explore the world of mating seahorses which are the only animals in the world that have a major gender role reversal.

This illuminating ten-part series tells the story of World War ll through the ten most pivotal turning points in the conflict. Gripping story-telling illustrated with exquisitely restored and colourised archived films and supported by a global cast of stellar historians bring this crucially important era in history to life.
In the first chapter, Britain and France declare war when Hitler invades Poland. In May 1940 the Germans attack Holland and Belgium as a decoy. As the Wehrmacht comes through the Ardennes and the Luftwaffe strikes in force, French leaders are caught like rabbits in headlights. The Germans are on a drug called Pervitin, which beats off fatigue, and reach the Atlantic coast. There is a danger that the Germans will encircle the Allies and cut them off from the sea. But Hitler issues his Halt Order and some 340,000 Allies are evacuated.

In 1940, France has fallen and Hitler orders Operation Sealion, the invasion of Great Britain. But first the Luftwaffe must defeat the RAF for seaborne landings to succeed. In July 1940 an epic struggle in the skies above England begins. Only a brilliant defensive system and the bravery of young pilots stand in the Luftwaffe’s way. Wave after wave of German bombers are attacked by British planes. Featuring the last interview with the youngest Spitfire-pilot in the battle, Geoffrey Wellum.