Black Holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question - what was there before the Big Bang? The trouble is that researching them is next to impossible. Black holes are by definition invisible and there's no scientific theory able to explain them. Meet the astronomers attempting to image a black hole for the very first time and the theoretical physicists getting ever closer to unlocking their mysteries. It's a story that takes us into the heart of a black hole and to the very edge of what we think we know about the universe.

20 years ago, two astronomers made a remarkable discovery, one which would change the way we view the universe for ever. A planet outside our solar system, orbiting a distant star - an exoplanet. Since then, we have found worlds where it rains diamonds, ones that boil at 3,000 degrees centigrade and even a world with four suns in its sky. But the big question is - will we ever find another Earth? As we close in on the discovery of the 2,000th planet outside our solar system, or exoplanet, we investigates the techniques that are revealing so much about these alien worlds. The documentary asks if we are really any closer to finding another world like our own - a second Earth.

The fifth programme explores the alliances formed between the animal and plant worlds. Attenborough dives into Australia's Great Barrier Reef and contrasts the nocturnal feeding of coral, on microscopic creatures, with its daytime diet of algae. Some acacias are protected by ants, which will defend their refuge from any predator. Besides accommodation, the guards are rewarded with nectar and, from certain species, protein for their larvae as well. Fungi feed on plants but can also provide essential nutriment to saplings (Mycorrhiza). The connection is never broken throughout a tree's life and a quarter of the sugars and starches produced in its leaves is channelled back to its fungal partners. Meanwhile, fungi that feed on dead wood leave a hollow trunk, which also benefits the tree. Orchids enjoy a similar affiliation. Lichens are the product of a relationship between fungi and a photosynthetic associate, usually algae. They are extremely slow-growing, and a graveyard is the perfect location to discover their exact longevity. Mistletoe is a hemiparasite that obtains its moisture from a host tree, while using own leaves to manufacture food. Its seeds are deposited on another by the mistletoe tyrannulet, following digestion of the fruit. The dodder (Cuscuta) is also parasitic, generally favouring nettles, and siphons its nourishment through periodic 'plugs' along its stem. The rafflesia has no stem or leaves and only emerges from its host in order to bloom — and it produces the largest single flower: one metre across.

For thousands of years, humans have believed that there were once flying monsters. But did they really exist beyond our nightmares? 220 million years ago dinosaurs were beginning their domination of Earth. But another group of reptiles was about to make an extraordinary leap: pterosaurs were taking control of the skies. The story of how and why these mysterious creatures took to the air is more fantastical than any fiction. In Flying Monsters 3D, David Attenborough the worlds leading naturalist, sets out to uncover the truth about the enigmatic pterosaurs, whose wingspans of up to 40 feet were equal to that of a modern day jet plane. Attenborough works with scientists to understand the incredible story of the evolution of the pterosaurs, a story that unfolds in such stunning locations as New Mexico, the Jurassic Coast of Lyme Regis in Britain, an ancient pterosaur landing site in Southern France and a fossil pit in Germany where near perfect pterosaur specimens have been found. The central question and one of the greatest mysteries in palaeontology is: how and why did pterosaurs fly? How did lizards the size of giraffes defy gravity and soar through prehistoric skies? Driven by the information he finds as he attempts to answer these questions, Attenborough starts to unravel one of sciences more enduring mysteries, discovering that the marvel of pterosaur flight has evolutionary echoes that resonate even today. Flying Monsters 3D is a groundbreaking film that uses cutting-edge 3D technology and CGI to bring the story of giant flying monsters and their prehistoric world to life. Audiences of all ages will be in awe as they enter the world and experience, as never before, REAL Flying Monsters in 3D.

Earth may seem like the most hospitable planet in the solar system. But look again. Startling new discoveries reveal the blue planet has been plagued by more chaos and destruction than scientists once imagined. Stand on the Earth billions of years ago as a primitive planet called Theia slams into it. Shiver as our entire globe is frozen over like a gigantic snowball. Feel the heat as mammoth volcanoes scorch the landscape and darken the sky. From a cosmic gamma ray burst frying away the ozone layer to an Everest-size asteroid slamming into the ocean, we'll reveal new information about how these unparalleled events drove life to the brink of total extinction. Out of this continuous devastation, how has our planet--and life--got to where it is today? Are the worst days behind us--or lurking in the distant future?

Many argue that flying saucers and other extra-terrestrial space ships continuously visit the earth. If that were true, what kinds of technologies would such alien spacecraft require? And do eyewitness reports of UFO sightings jibe with modern theories of how interstellar travel might be possible? Authors, astronomers and theoretical physicists weigh in with the blueprints for inertia-canceling devices, nuclear-powered craft, antimatter propulsion systems and even warp drives. Based on Einstein's theories and countless scientific studies, we'll find out how these visitors might bridge the vast distances between the stars. And if they could survive such hazardous journeys, are they flesh and blood or intelligent machines?