The series starts by looking at the power of the sun. The most enchanting illustration of the sun's hold on life takes place in the Arctic spring.
A mother polar bear emerges from her winter den with her two cubs. She has just two weeks to prepare them for a hazardous journey across a frozen sea before it melts and they become stranded. During this critical period, Planet Earth captures the most intimate and complete picture of polar bear life ever filmed.
The tilt of the Earth's orbit to the sun creates seasons, which in turn trigger the greatest spectacles on the planet, the mass migration of animals.
Using aerial photography, we watch as a million caribou trek across the Arctic wastes, pursued by wolves as they go, and an epic journey taken by hundreds of elephants as they head for the Okavango swamps.
Finally we visit the oceans, and see the leap of a great white shark as it captures a seal. The action, which last all of one second in reality, is shown in slow motion over 40 seconds, highlighting the power of this mighty predator.
We go on to examine the geological and volcanic forces that shaped the land and its mountain chains. Planet Earth takes you on a tour of the mightiest mountain ranges to discover puma in the Andes, grizzly bears in the Rockies and cranes in the Himalayas. There is also spectacular footage of a snow leopard hunting on Pakistan's peaks, and a giant panda nursing its week-old baby in a mountain cave in China.
From there we look at fresh water, following the descent of rivers from their mountain sources down to the sea, showcasing the unique wildlife found there, from Angel Falls in Venezuela, to Iguacu Falls in Brazil to the world's deepest lake, Lake Baikal in Siberia, home to the only freshwater seal on Earth and giant prehistoric amphipods.
We also have dramatic pictures of Nile crocodiles pulling down wildebeest - shot for the first time on ultra-high-speed cameras - and astonishing footage from the tidal salt marshes of the eastern United States of 400,000 flocks of snow geese.
We venture into the unknown, underground cave systems of the world to see angel fish, bats and mysterious troglodytes, which never see daylight nor ever set foot outside their cave. We visit the globe's deserts, to see rare Bactrian camels that survive in the Gobi by eating snow in lieu of water, and the Atacama in Chile, where guanacos survive the driest desert in the world by licking the dew from cactus spines.