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 second programme deals with the mechanics of flight. Getting into the air is by far the most exhausting of a bird's activities, and Sir Attenborough observes shearwaters in Japan that have taken to climbing trees to give them a good jumping-off point. The albatross is so large that it can only launch itself after a run-up to create a flow of air over its wings. A combination of aerodynamics and upward air currents (or thermals), together with the act of flapping or gliding is what keeps a bird aloft. Landing requires less energy but a greater degree of skill, particularly for a big bird, such as a swan. Weight is kept to a minimum by having a beak made of keratin instead of bone, a light frame, and a coat of feathers, which is maintained fastidiously. The peregrine falcon holds the record for being fastest in the air, diving at speeds of over 300 km/h. Conversely, the barn owl owes its predatory success to flying slowly, while the kestrel spots its quarry by hovering. However, the true specialists in this regard are the hummingbirds, whose wings beat at the rate of 25 times a second. The habits of migratory birds are explored. After stocking up with food during the brief summer of the north, such species will set off on huge journeys southwards. Some, such as snow geese, travel continuously, using both the stars and the sun for navigation. They are contrasted with hawks and vultures, which glide overland on warm air, and therefore have to stop overnight.

Professor Brian Cox continues his epic exploration of the cosmos by looking at the faint band of light that sweeps across the night sky - our own galaxy, the Milky Way. The Sun is just one of almost 400 billion stars that form this vast, majestic disk of light, our own home in the universe. Thanks to a cutting-edge space we’re finally able to reveal the Milky Way’s dramatic history and predict its cataclysmic future.
Our galaxy started out a fraction of the size it is today, and Gaia telescope has revealed how it grew over the eons. Beautifully rendered VFX based on the very latest Gaia data has uncovered the remarkable story of our galaxy’s evolution. As our young galaxy encountered rival galaxies, it experienced a series of violent growth spurts and intense periods of cataclysmic change while battling to survive. Each time our galaxy feeds, a new era of star formation begins, fuelled by incoming torrents of fresh gas and energy. And there is another collision to come. Another, larger galaxy is coming our way. Andromeda is heading straight for us at a quarter of a million miles per hour. The Milky Way’s long-term fate is in the balance.

The magnificent ringed planet Saturn, along with its more than 80 moons, forms the most dynamic planetary system in our neighborhood. With underground oceans and protective magnetic fields, experts are exploring how this collective of satellites has the potential to rewrite the rules of the Solar System.
The closer that we look, the more we see these extraordinary moons like worlds of their own -- so dynamic, so Earth-like. Almost a billion miles from the Sun, these icy worlds could be home for Life 2.0. The moons of Saturn offer possibly the best chance of finding extraterrestrial life in our solar system. With each new mission, we get closer to unraveling the mysteries of Saturn's moons.

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.

A look at how the Sun was formed and how it could potentially die; its physical composition; how it makes energy; and the nature of solar eclipses, solar flares and sunspot activity. Behold the sun and all of its glory. Learn all things about the sun ranging from its beginning to its death. Also learn about how stars work in general and MUCH, MUCH more.