In 2014, the International Space Station had to move three times to avoid lethal chunks of space debris and there is an increasing problem of satellites mysteriously breaking down. With first-hand accounts from astronauts and experts, know the scale of the problem of space junk. Our planet is surrounded by hundreds of millions of pieces of junk moving at 17,000 miles per hour. Now the US government is investing a billion dollars to track them, and companies around the world are developing ways to clear up their mess - from robot arms to nets and harpoons. Learn the science behind the hit film Gravity and discovers the reality is far more worrying than the Hollywood fiction.

In Africa's ancient south west corner, two extraordinary deserts sit side by side. Water is in short supply, yet these deserts are somehow full of life because the creatures that live here have turned the rules of survival on their head. This film celebrates nature's ingenuity, no matter how tough it gets. In the Kalahari scrublands, clever meerkats are outsmarted by a wily bird, solitary and belligerent black rhinos get together to party and giant insects stalk huge flocks of birds. Rain almost never falls in the Namib - instead it must make do with vaporous, vanishing fog. The creatures in this, the world's oldest desert, have gone to the extremes, as spiders wheel to escape and a desert giraffe fights to defend his scant resources in the greatest giraffe battle ever filmed.

Our universe seems real. But what if it’s a videogame? Scientists in a variety of fields are taking seriously the possibility that we live in a virtual reality. Maybe the Big Bang was just the moment someone flipped the switch and turned on our universe. Maybe what looks random has already been programmed to happen. If some advanced civilization did design and program our universe, would we ever know? Scientists are looking for glitches in the laws of the universe that may uncover its hidden code.

Tyson begins the episode by explaining the nature of the speed of light and how much of what is seen of the observable universe is from light emanated from billions of years in the past. Tyson further explains how modern astronomy has used such analyzes via deep time to identify the Big Bang event and the age of the universe. Tyson proceeds to describe how the work of Isaac Newton, William Herschel, and James Clerk Maxwell contributed to understanding the nature of electromagnetic waves and gravitational force, and how this work led towards Albert Einstein's Theory of Relativity, that the speed of light is a fundamental constant of the universe and gravity can be seen as distortion of the fabric of space-time. Tyson describes the concept of dark stars as postulated by John Michell which are not visible but detectable by tracking other stars trapped within their gravity wells, an idea Herschel used to discover binary stars. Tyson then describes the nature of black holes, their enormous gravitational forces that can even capture light, and their discovery via X-ray sources such as Cygnus X-1. Tyson uses the Ship of Imagination to provide a postulate of the warping of spacetime and time dilation as one enters the event horizon of the black hole, and the possibility that these may lead to other points within our universe or others, or even time travel. Tyson ends on noting that Herschel's son, John would be inspired by his father to continue to document the known stars as well as contributions towards photography that play on the same nature of deep time used by astronomers.

Andrew Graham-Dixon examines early Christian art and the reasons for its evolution during the Renaissance. He also reveals just how far modern artists have been influenced by the pre-perspective view of the world.

Dr Adam Rutherford tells the extraordinary story of the scientific quest to discover the secrets of the cell and of life itself. Every living thing is made of cells, microscopic building blocks of almost unimaginable power and complexity. The first part explores how centuries of scientific and religious dogma were overturned by the earliest discoveries of the existence of cells, and how scientists came to realize that there was, literally, more to life than meets the eye.