Saturn's secrets are out. The ferocious weather, the evolving ring system and the discovery of active geology on Saturn's moons has rewritten the textbooks. Scientists are looking for life on Saturn's moons and they may have found it on Titan.

Orbits are the dynamics that drive the universe. From the smallest asteroid to the largest super-cluster, everything in the universe is in orbit. We owe our very existence to the stability of earth's orbit — it gave us life and keeps us safe. But we are the freaks. Everywhere else we look we find orbits are chaotic, unstable, and violent. Beyond our solar system we find planets that are blow-torched, stars that eat each other, and black holes that destroy everything in their path. Yet on the very largest scale, orbits are also a creative force. clashing galaxies give birth to new stars and new worlds. on the galactic scale orbits even construct the fabric of the universe itself.

The Milky Way, our galaxy, is a magnificent sight in the night sky, but we know surprisingly little about it for certain. What is its shape? How many stars does it actually contain? What lies at its centre? The Gaia space telescope will answer these questions, being armed with the most advanced camera to leave our planet, and it will allow us to see our galaxy as we've never seen it before. The Sky at Night visits the factory in Chelmsford that made the astonishing sensor at the heart of the mission.

Professor Brian Cox concludes his exploration of our place in the universe by asking what next for the ape that went to space. Our future is far from certain. In Florida, Brian joins the latest efforts to protect Earth from potential catastrophic events. He joins a team of Nasa astronauts who are training for a future mission to an asteroid - should we ever discover one coming our way - under 30 feet of water in a submerged laboratory that simulates space. It is just one example of how, for our long-term survival, space exploration may well be vital. It is a view shared by Apollo 16 astronaut Charlie Duke, who tells Brian what it was like to escape the confines of the planet. It is a dream that both Nasa and now commercial companies share as they race to get humans back into deep space.
But space travel, like every leap our civilisation has ever made, requires energy. Here too, scientists are hard at work attempting to safeguard our future. At the National Ignition Facility in California, Brian witnesses the world's most successful fusion experiment in action. He believes that if their mission succeeds, our civilisation will have unlocked a way to the stars that will not destroy the planet in the process. Brian concludes by returning to the top of the world in Svalbard, where he gains access to our civilisation's greatest treasure, locked away in a vault buried deep in the permafrost.

According to the laws of physics we can never travel faster than the speed of light...or can we? Learn all about light speed, the ultimate constant in the universe.

Time is woven into the fabric of the universe as one of the dimensions in which we live our daily lives. But maybe it is only a brain state that we use to piece together events. Could it exist only in our minds? Your sense of time can be totally different than the person next to you. This and other theories illustrate that time is an illusion and does not really exist. The world's top physicists tackle this fundamental question, does time exist, and offer new ways to perceive the physical world.