A Perfect Planet

Episode
Episode 2 - Sun
Broadcast Info
2021 (57 mins)
Description
Life on our planet is powered by a solar force - the Sun. Every patch on Earth gets 4,380 hours of sunlight a year but in different doses depending on where you are: a variation that shapes much of the natural world. Seasonal variations in light are due to the fact that the Earth does not spin upright on its axis, but on a tilt - 23.5 degrees - which means different parts of the planet are angled towards the sun at different times of the year. Through close-up, personal stories of beguiling animal characters, this episode reveals how the planet’s living things have come up with brilliant adaptations to survive the uneven amounts of sunlight triggered by this tilt. The exception is on the equator where the duration of day and night remain the same throughout the year. Here, we discover how this guaranteed sunlight drives the great diversity of life we call the tropical jungles. Jumping into the canopy with acrobatic, fruit-eating gibbons, we enter the strange macro world of the fig wasp, revealing their spellbinding relationship with the jungle’s most important tree. But the jungles’even day/night cycle is not the norm on Earth. Thanks to the way our planet spins and moves along its orbit, the further you get from the equator, the longer the power cuts will be at some point in the year. At the extreme ends of the Earth - the Poles - the loss of solar power lasts not for half a day but for nearly half a year. With no sunlight energy for several months, the atmosphere chills, temperatures plummet and water freezes. In these parts, the perfect planet seems almost unlivable, unless you are an Arctic wolf or muskox - supreme polar specialists in surviving long periods without sunlight. Animals have come up with ingenious solutions to deal with the differences in the Sun’s energy across the globe. In places where solar radiation is extreme, like the Sahara, silver ants have evolved adaptations that make them masters in coping with too much sunlight. At the opposite end of the scale, during winter’s chill, wood frogs have found a way to save energy by allowing themselves to freeze solid, like a block of ice. In this suspended animation their hearts stop beating completely. The seasonal shift in the Sun’s power across the Earth means that in some places residents must cram a full life into short periods of time. For Canada’s most northerly reptile, the garter snake, the warming temperatures of late Spring trigger the largest emergence of snakes on earth. In a little over a week, and powered by the Sun’s energy, tens of thousands of writhing snakes take part in a mass mating ritual. For Arctic foxes these are also times of feverish activity, cramming feeding, hunting and breeding for the entire year into a few summer months, so that they are prepared for when the light starts to fade. When daylight shortens, the only option for many plants is to sit out the increasing periods of darkness by shutting down all together - seen in the drama and beauty of Autumn. For the golden snub-nosed monkeys of China’s seasonal forests, life or death is determined by a narrow window where they must stockpile enough energy resources to survive winter’s power cut. But there is an alternative; a way to escape the solar power cut that comes with winter. When the cold starts to bite in the Southern Hemisphere, thousands of sooty shearwaters set off from Snares’Island in New Zealand and head north - chasing the sun on an epic 10,000-mile migration to arrive in Alaska’s Aleutian Islands for summer. Here, the shearwaters are joined by hundreds of humpback whales in one of the most dynamic and thrilling feeding spectacles on Earth. By avoiding the extremes of winter, these animals have found a way to cheat the Planet’s tilt and live in an eternal summer.
Genre
Natural History; Climate

How to cite this record

The Open University, "A Perfect Planet". https://learningonscreen.ac.uk/ou/search/index.php/prog/238037 (Accessed 10 Jan 2025)