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The power of the sun drives the seasons transforming our planet.
Vast movements of oceans and air currents bring dramatic change throughout the year.
And in a few special places, these seasonal changes create some of the greatest wildlife spectacles on earth.
Here in the Arctic summer the sun begins to melt the winter ice.
Nearly 3 million square miles of ice will disappear, opening up a narrow window of opportunity for millions of animals.
For many, it's their best chance to feed and breed.
But for polar bears, it's the hardest time of the year.
They had to survive the greatest seasonal change on the planet.
Natures great events the great melt winter in the Arctic.
The Northern Lights flicker across the sky.
It's a land of continuous night, where temperatures plummet to -40.
Polar bears are in their element, hunting for seals on the forzen sea.
Bu the long night is coming to an end.
In February, the sun rises for the first in four months.
In the coming weeks, the strength of the sun will power an enoumous change.

But for now, its ray offers only a little warmth.