In this bird's-eye view of two continents, demoiselle cranes negotiate a dangerous Himalayan pass on their way to India while high-flying bar-headed geese take the fast track five miles above. In Rajasthan, vultures watch hunting tigers hoping for a meal and pigeons visit a temple dedicated solely to sacred rats. Pigeons are also our guide to the greatest gatherings of camels on Earth and learn to dodge buzzards around the battlements of Jodhpur Fort. 9,000 cranes overwinter in the most unlikely of spots - a barbed wire compound in the centre of a desert town. In Australia, rainbow lorikeets drop in on Sydney and patrol Australia's Gold Coast. In the outback, white cockatoos swirl in thousands and budgerigars pass Uluru (Ayers Rock) and gather in the biggest flocks ever recorded. In China, swallows and swifts visit the Great Wall and the Forbidden City of Beijing. In Japan, the country's most revered birds - Japanese cranes are fed fish by appreciative locals and are joined in strange, momentary harmony by hungry red foxes, white-tailed eagles and Steller's eagles. As peace descends, Japanese cranes dance beautifully in the snow.

Black holes are the most enigmatic and exotic objects in the universe. They’re also the most powerful; with gravity so strong it can trap light. And they’re destructive, swallowing entire planets, even giant stars. Anything that falls into them vanishes... gone forever. Now, astrophysicists are realizing that black holes may be essential to how our universe evolved—their influence possibly leading to life on Earth and, ultimately, us.
In this series, astrophysicist and author Janna Levin takes viewers on a journey to the frontiers of black hole science. Along the way, we meet leading astronomers and physicists on the verge of finding new answers to provocative questions about these shadowy monsters: Where do they come from? What’s inside? What happens if you fall into one? And what can they tell us about the nature of space, time, and gravity?

Of all the objects in the cosmos, planets, stars, galaxies, none are as strange, mysterious, or powerful as black holes. Black holes are the most mind-blowing things in the universe. They can swallow a star completely intact. Black holes have these powerful jets that just spew matter out.
First discovered on paper, on the back of an envelope, some squiggles of the pen. The bizarre solution to a seemingly unsolvable equation, a mathematical enigma. Einstein himself could not accept black holes as real. People didn't even believe for many years that they existed. Nature doesn't work that way. Yet slowly, as scientists investigate black holes by observing the effect they have on their surroundings, evidence begins to mount.

Astronomers are giving us astonishing news, visual proof of the reality of black holes. Stunning new findings are overturning conventional theories. The most common vision of black holes is that they are monstrous and mysterious bodies swallowing everything around them. However, the latest discoveries are drawing a link between black holes and the existence of life. A startling new picture is emerging. The existence of black holes is what made life on Earth possible.

The Cave of Swallows in Mexico is a 400m vertical shaft, deep enough to engulf the Empire State Building. The Lechuguilla cave system in the USA is 193km long and 500m deep with astonishing crystal formations hanging from its chambers. Although often overlooked, caves are remarkable habitats with equally bizarre wildlife. Cave angel fish cling to the walls behind cave waterfalls with microscopic hooks on their flattened fins. Cave swiftlets navigate by echo-location and build nests out of saliva. The Texas cave salamander has neither eyes nor pigment. Unique access to a hidden world of stalactites, stalagmites, snotites and troglodytes brings a wealth of surprises.

Earthflight departs on its grand European tour, using a host of techniques including taking extraordinary footage from microlites as they fly alongside imprinted birds. Among other wonders, cameras soar with cranes and geese over Venice, the white cliffs of Dover and Edinburgh. White storks leave Africa and struggle to reach Istanbul, the gateway to Europe, while cranes take an easier route over the monkey-guarded Rock of Gibraltar. In France, the white horses of the Camargue make a splash around the new arrivals. In Rome, the heat of the city lures 20 million starlings that perform nature's greatest aerial display to outwit peregrines. In Hungary, sand martins grab mayflies from the air; and at Bass Rock, gannets create Britain's greatest natural spectacle as they dive in exquisite slow-motion. The story takes an emotional turn as storks and swallows wait for their partners to return and indulge in a spot of DIY to impress. Finally, geese touch down in Svalbard to raise a family. To protect their young, a squadron of birds assemble to see off polar bears. With views of birds flying over the Loire Valley, London docklands and the bulb fieds of Holland, this is Europe as never before.