Travel to heart of the Sun, our star, a cauldron of superheated gases that writhe and contort along immense magnetic field lines. Discover how even life itself is forged in the heart of stars. We are made of stardust.

Scorched by their proximity to the sun, Mercury and Venus are hostile worlds; one gouged with craters from cosmic collisions and the other a vortex of sulphur, carbon dioxide and acid rain. Prime examples of planets gone awry, do they serve as a warning for ominous scenarios that might someday threaten Earth?

The center of our galaxy is one of the most nightmarish places in the cosmos. It's the home to some of the most incredible forces the universe has to offer. Gas streaming everywhere, stars are being born and dying and exploding, radiation blasting out. And at the very heart is the super massive black hole, 4 million times the mass of the sun. But also the Milky Way, is our safe harbour, our island in this vast, cosmic ocean. And so to understand the heart of our galaxy, is to understand our home in this cosmic void.

At the top of our planet lies a magical realm, the Arctic Ocean. After four months of winter darkness, the sun returns to reveal a frozen ocean covered in ice. Mother polar bears emerge from their hillside dens and lead their cubs down to the sea ice to hunt, while a young male and female bear forge a surprising friendship out on the ice.
For others, the frozen sea is a trap. A pod of beluga whales has been confined to an ice hole for five months, slowly starving to death as the food around them runs out. Their salvation lies in the strengthening sun that comes with spring, melting the sea ice, allowing their escape.
Off the east coast of Greenland, the floating pack ice in spring is a nursery ground for harp seals. Mothers and pups have just a few weeks together for the pup to learn to swim before she leaves him to fend for himself. But in today’s warming climate, storms can tip helpless youngsters into the sea before they are strong enough to fend for themselves.
Summer is a time of plenty in the Arctic Ocean as plankton blooms feed millions of tiny mouths, such as bizarre skeleton shrimps, as well as the biggest: bowhead whales. These ancient and long-lived whales arrive en masse every year at secret locations known as whale spas. But today, with the loss of summer sea ice, their peace is shattered by orcas from the south. These daring predators are bold enough to take on the much larger bowheads, targeting their vulnerable calves.
The 24-hour daylight of the Arctic summer attracts visitors from afar, including huge flocks of seabirds like crested auklets. A male must use both his song and a secret tangerine perfume if he is to attract a mate. For the resident walrus, the summer heat can be unbearable. After hauling himself to the beach to moult, an old male uses an ingenious technique to get himself back to the cool of the water - a roly-poly!
Summers in the Arctic today bring record-breaking heat. With climate change, it is warming faster than anywhere else on Earth. It is predicted that the Arctic Ocean could become ice-free each summer by 2035, raising new challenges for polar bears. Without sea ice, more and more bears are becoming stranded on remote Arctic islands. It's a dangerous place to be for a mother bear with cubs, surrounded by larger, predatory males.

There's a killer lurking in our galaxy, a star ready to explode into a supernova. Seen from Earth, a supernova in the Milky Wave would have a terrible beauty. But for us, it could be fatal. In a few seconds, it can release as much energy as the sun will over its entire lifetime. It could be anywhere. It is nearly impossible to predict where and when the next supernova will happen. The hunt is on to find the next supernova before it finds us.

Each night, across the planet, our cities illuminate the darkness. Their lights burning brighter than ever before. And whilst we're asleep, animals are making the most of this new neon landscape. The sunset in Los Angeles, Chicago, and Toronto creates worlds of opportunities for the cleverest animals willing to take the risk.