Perhaps the most mysterious structure on Earth, Stonehenge has stood on a plain in Southern England for 5000 years. Its foundations predate the Great Pyramids. It is one of mankind's most ancient mysteries. Why is it here? Is it a temple? A burial ground? A place for sacrifice? Or could the mystery of Stonehenge be revealed in its builders' desire to explore the unknown heavens and touch the universe? Using the cutting-edge computer-generated imagery that takes us into deep space, we'll also go inside a virtual Stonehenge to see what the ancients saw and push this prehistoric marvel to give up its age-old secrets.
In this episode we explore the possibility that this was a prehistoric astronomical observatory. Here ancient astronomer priests may have divined the complex movements of the Sun and Moon, recognizing patterns that would not be discovered elsewhere for thousands of years. The primitive Shamans may have also been the first astronomers to predict eclipses.

Recently, the Event Horizon Telescope project captured the first image ever of a black hole. Now, new discoveries might finally reveal how supermassive black holes are made, and using the latest technology, experts are on the verge of understanding how these monsters grow and how they affect life on our planet.
Supermassive black holes: Gargantuan monsters that lurk at the center of galaxies. Right now you are travelling at half a million miles an hour around a giant black hole four million times the mass of the sun. But there's a mystery about these colossal beasts. We have no idea where they came from. How did they get so big so quickly?

The film captures the global challenge to lead the clean energy future by profiling U.S. and Chinese workers and business leaders who are racing to make crucial breakthroughs in the field. Catching the Sun debunks a false dilemma that clean energy requires sacrificing economic prosperity.
Through the stories of an unemployed American worker, a Tea Party activist, and a Chinese solar entrepreneur, we will explore the global energy transition from the perspective of workers and entrepreneurs building solutions to income inequality and climate change with their own hands. Their successes and failures speak to one of the biggest questions of our time: will the countries actually be able to build a clean energy economy?

Stonehenge was shaped over centuries, but to what purpose? Was it a temple to the sun, or the moon, an astronomical calendar, or a shrine to dead ancestors? Now Stonehenge may be about to give up some of its secrets. For the first time in nearly half a century a new archaeological dig the sacred stone circle. And the men who are leading the excavation are well aware of the significance of this moment.
The film exposes an investigation into a radical theory that Stonehenge, far from being a place of burial as is commonly assumed, was in fact a place of healing. The investigation takes in forensic testing of bones excavated over the past decades and hard-won permission for the first dig in 50 years at the Henge, watched live online by millions of viewers around the world. Does the theory of the healing stones bear up to modern-day forensic science?

About 340 million years ago a brand new family of animals was evolving in the primeval swamps. They were to go one step further than the amphibians who had emerged onto dry and before them. For they would eventually completely cut their ties with water. They were the ancestors of todays lizards. They evolved scaly impermeable skins and moved up into the forests. They diversified into a multitude of different shapes and sizes. They developed signalling systems to communicate with one another. And they squabbled as animals do. For food they hunted insects that were already well established on the land in great numbers. And here without returning to water they produced their families. They powered their bodies not only with food but with the heat that they drew directly from the sun.
As they diversified so they spread into the harshest of the lands habitats. The baking waterless deserts which eventually they would come to dominate. Discover jacky lizards that wave, wrestling beaded lizards and the the world's smallest chameleon, which is no bigger than his thumbnail, and the biggest lizard in Australia.

The Sundarbans mangrove forest, in Bangladesh near the Indian border, is a tidal jungle where Ganges and Brahmaputra enter the Indian Ocean. Its has some 400 Bengal tigers - the largest population in the world, and the only to be hardly scared of men. The downside is tigers kill up the 50 Bangladeshis a year, even from neighbouring villages, so keeping them inside the reserve is key to long-term survival.
A recent project tries to train local mongrels, not pets but fiercely self-reliant dogs, to spot and even scare off tigers from villages. An individual tiger can turn into a man-eater in order to survive - this process may occur due to an injury or old age (and so cannot hunt agile prey) or even accidentally tasting human flesh.