The Sky at Night - Season 60 / Year 2016

On January 20 2016, two American astronomers made an extraordinary claim - they had found evidence for a ninth planet in our solar system, a planet 20 times further out than Neptune which would take up to 20,000 years to orbit the sun. It is a discovery that could completely rewrite our understanding of our solar system and how it formed.

As the world's biggest telescopes start scanning the skies searching for Planet 9, the Sky at Night team investigates. If Planet 9 exists, where is it and where did it come from?

In California, Chris Lintott meets the astronomers whose study of the distant Kuiper Belt led them to predict the existence of the planet. And while some scientists are still sceptical, Maggie Aderin-Pocock discovers how our models of the formation of the solar system and the discovery of similar exoplanets around other stars all support the existence of Planet 9.

For 50 years we have been sending probes to gather close-up images of the other planets and moons of the solar system. The Sky at Night presents the five greatest images captured by those spacecraft. From a view of the surface of Mars, to live pictures of the sun and a unique picture of our own planet, these are the images that have transformed our perception of the solar system we live in.

The programme looks at the latest understanding of black holes, featuring an interview with Stephen Hawking. Black holes are one of the greatest mysteries in the universe. They behave in a way that is contrary to laws of physics and one has never actually been seen. However, the recent detection of gravitational waves, as predicted by Einstein, proves that black holes exist and provides a way to investigate their remarkable behaviour and properties.

May 9th 2016 sees one of the astronomical highlights of the year - a transit of Mercury across the sun, the best opportunity to observe this phenomenon until 2049. To mark the event, the Sky at Night attempts to explain the many mysteries of Mercury - a planet so bizarre that it is sometimes described as the 'problem child' of the solar system. Surface temperatures exceed 450 degrees but it also has patches of ice, its day is twice as long as its year, and it is a planet that appears to be shrinking.

The Sky at Night focuses its attention on M51 aka the Whirlpool Galaxy. Sitting approximately 30 million light years from Earth, this spiral galaxy was discovered in 1773 by the French astronomer Charles Messier. It is thought to have been the inspiration behind the swirling patterns of van Gogh's Starry Night. June 1st has been declared Whirlpool Galaxy Day. On this one day we will be aiming as many telescopes as possible at the galaxy. Images will be taken by optical and infra-red telescopes on top of volcanoes in Hawaii and La Palma, the radio signature will be captured at the Mullard Radio Astronomy Observatory in Cambridge, and in orbit the Swift space telescope will aim its ultraviolet and X-ray sensors at the galaxy. By examining the galaxy at as many magnifications and wavelengths as possible the programme will build up a portrait of this galaxy - unlocking the secrets of the formation of the spiral arms and revealing how they have triggered a wave of intense star formation.

A look behind the scenes of Nasa's project to study Jupiter. As the spacecraft Juno enters Jupiter's orbit, the programme explores the dangers of the mission and what Nasa is hoping to discover about the giant planet - from the secrets of its formation to the source of the solar system's most powerful aurora.

Following the recent discovery of an Earth-like planet orbiting Proxima Centauri, the Sky at Night focuses on our nearest neighbouring star. As well as telling the story of the of the discovery of the new planet and revealing what conditions may be like on its surface, the team is also joined by Professor Jim al-Khalili to investigate the possibility of building a spaceship that could travel the 4.23 light years to Proxima Centauri.

The Sky at Night goes behind the scenes at the European Space Agency as the Rosetta mission reaches its conclusion and the spacecraft is crashed into the surface of comet 67P Churyumov-Gerasimenko. For nearly two years the Rosetta spacecraft has been in orbit, studying the comet at close range and returning extraordinary pictures. But now the the mission must end and the project scientists have decided to have one final attempt at studying it at close range. On September 30th the spacecraft - with all its instruments running - will be crashed into the surface of the comet. Its aim is to get the best ever view of the mysterious pits on the comet's surface, pits whose walls are thought to have been undisturbed for over 4 billion years. Chris Lintott will be in mission control with the scientists as they watch the pictures come in from the spacecraft's dive towards the surface. Maggie Aderin-Pocock will be investigating how the mission has transformed our understanding of comets.

The Sky at Night team investigates the ongoing hunt for life on Mars. It is one of the great scientific questions of our time, but are we any closer to finding an answer? As well as uncovering the cause of the recent crash of the Schiaparelli lander, the team looks at the next missions designed to hunt for life on the red planet - from a rover designed to drill deep into the surface, to the orbiter sniffing for signs of methane in the atmosphere. Adam Rutherford joins the team to ask if we have been deliberately avoiding the most likely places to find life on Mars.

The Sky at Night team looks back on the major stories of the year and sees how they have developed since they hit the headlines. 2016 has been a remarkable year in many ways, but one area in which it has been particularly good is in space science. There have been new missions to Jupiter and Mars, planets have been found on the outskirts of the solar system and around our nearest neighbouring star, and the discovery of gravitational waves has potentially given us a new way of investigating the universe. What has the Juno probe discovered at Jupiter? Has Planet 9 been found? And are we any closer to finding Earth-like planets elsewhere in the galaxy?