What if aliens landed on Earth? Much of science fiction explores the moment of first contact – what will people do when the aliens land? From H. G. Wells’ pioneering The War of the Worlds to Independence Day, Men in Black, and District 9, Invasion deals with our fears of alien invasions of earth. David Tennant explains the appeal of Doctor Who’s Daleks and Cybermen while John Carpenter and Chris Carter explore the rich appeal of the paranoia fuelled by hidden aliens with The Thing and The X-Files. It also asks, what if the monsters were our own creation? With the aid of rarely seen animation tests, Phil Tippett takes us behind the scenes in the creation of the dinosaurs of Jurassic Park. But not all invasions are hostile. Peter Coyote and Richard Dreyfuss discuss the creation of Spielberg’s spellbinding classics E.T. the Extra-Terrestrial and Close Encounters of the Third Kind. There is more than one kind of invasion.

As they prepare their counterattack against Caesar, Pompey's Republicans begin to squabble over both the anticipated spoils and the method of finishing Caesar off. Badly outnumbered, Caesar and Antony make their stand at Pharsalus. As they try to reach Caesar in Greece, the shipwrecked Vorenus and Pullo confront an unexpected dilemma.
Back in Rome, Atia again sends Octavia to beg protection from Servilia, who complies readily to encourage her growing friendship with Octavia. Niobe's sister Lyde comes back to see her and comforts her over Vorenus's disappearance.

There's something very odd going on in space - something that shouldn't be possible. It is as though vast swathes of the universe are being hoovered up by a vast and unseen celestial vacuum cleaner. Sasha Kaslinsky, the scientist who discovered the phenomenon, is understandably nervous: 'It left us quite unsettled and jittery' he says, 'because this is not something we planned to find'. The accidental discovery of what is ominously being called 'dark flow' not only has implications for the destinies of large numbers of galaxies - it also means that large numbers of scientists might have to find a new way of understanding the universe. Dark flow is the latest in a long line of phenomena that have threatened to rewrite the textbooks. Does it herald a new era of understanding, or does it simply mean that everything we know about the universe is wrong?

Time i s a concept which is so familiar, and yet recent discoveries have revealed it to be far stranger than we could have possibly imagined. In the final programme in the series, Brian explores the enigma of time - a phenomenon we take for granted but which is one of the biggest mysteries in the universe. He recalls highlights from his TV series that touch upon this conundrum.

Are the rings of Saturn a real celestial phenomenon or merely a cosmic Illusion? Technology allows the experts to get closer to the furthest planet visible to the naked eye. Old questions are answered and new ones arise. Does Saturn hold the key to Earth's weather and will one of its moons supply us with all the oil we'll ever need?

In this series, we will explore how we can survive Mars. Our species will need to evolve how we eat, drink, and build our homes. In the first episode, humans seem to be on the cusp of reaching Mars, but how did we get to this point? Our journey to our neighboring planet traces a path connecting Nikola Tesla, Nazi weapons of war, a Cold War space race, and a string of blockbuster discoveries made by some of NASA’s most talented robots.