Is there any way to slow or even prevent the ravages of time? Veteran presenter Johnny Ball looks back over the 45 years that Horizon - and he - have been on air to find out what science has learned about how and why we grow old.

It's a macabre paradox, but almost every advance in aviation safety has been driven by a crash. After every crash, investigators determine its cause and scientists make every effort to ensure the same mistakes never happen again.

Twenty-five years after the world wide web was created, it is now caught in the greatest controversy of its existence - surveillance.

Recent research has analysed the link between the harmful effects of drugs relative to their current classification by law with some startling conclusions. Perhaps most startling of all is that alcohol, solvents and tobacco (all unclassified drugs) are rated more dangerous than ecstasy, 4-MTA and LSD (all class A drugs). If the current ABC system is retained, alcohol would be rated a class A drug and tobacco class B.

Dark flow is the latest in a long line of phenomena that have threatened to re-write the textbooks. Does it herald a new era of understanding, or does it simply mean that everything we know about the universe is wrong?

Horizon explores the strange and wonderful world of illusions - and reveals the tricks they play on our senses and why they fool us.

Dr Michael Mosley and Professor Alice Roberts investigate if male and female brains really are wired differently.

Professor Iain Stewart examines the powerful geological forces that unleashed the devastating Japanese earthquake, and explores how the release of this power of the planet brought Japan to the brink of a nuclear meltdown.

Jimmy Doherty, pig farmer, one-time scientist and poster-boy for sustainable food production is on a mission to find out if GM crops really can feed the world.

'To send a spacecraft there is a little bit insane,' says Scott Bolton when talking about Jupiter, the largest planet in the solar system. But that is exactly what he has done, because Scott is head of Juno, the Nasa mission designed to peer through Jupiter's swirling clouds and reveal the wonders within.

Horizon goes behind the scenes at Nasa to discover how it is preparing for its most ambitious and daring mission: to land men - and possibly women - on the surface of Mars.

The intriguing possibility of life on Mars has fuelled man's quest to visit the Red Planet. Drawing on 45 years of Horizon archive, space expert Dr Kevin Fong presents a documentary on Earth's near neighbour.

Transplant surgery has now reached incredible heights, from achieving full face transplants to growing organs in the lab. This Horizon Guide looks back at the extraordinary odds doctors and patients have had to overcome to achieve these amazing breakthroughs.

Dr Kevin Fong explores a medical revolution that promises to help us live longer, healthier lives. Inspired by the boom in health-related apps and gadgets, it's all about novel ways we can monitor ourselves around the clock. How we exercise, how we sleep, even how we sit.

A look at people living with OCD, the therapy available and what neuroscience can offer.

Science series. People like to think they are in control of their lives - of what they feel and think. But scientists are now discovering this is often simply an illusion.

Adam Rutherford meets a new creature created by American scientists - the spider-goat. It is part goat, part spider, and its milk can be used to create artificial spider\'s web.

Friendly bacteria, superfoods, cholesterol busting spreads, 99% germ free, whiter than white...it's almost impossible to find a product in the supermarket today that doesn't come with impressive claims, scientific claims with an inflated price tag to match. Are they oversold? Or are they worth the extra cash?

This is the story of an extraordinary scientific adventure - the attempt to control gravity. For centuries, the precise workings of gravity have confounded the greatest scientific minds - from Newton to Faraday and Einstein - and the idea of controlling gravity has been seen as little more than a fanciful dream. Yet in the mid 1990s, UK defence manufacturer BAE Systems began a ground-breaking project code-named Greenglow, which set about turning science fiction into reality.

Nobel Prize winner Sir Paul Nurse examines why science appears to be under attack.

Around the world, a new generation of astronomers are hunting for the most mysterious objects in the universe. Young stars, black holes, even other forms of life.

Dr Michael Mosley seeks to establish the truth about meat. Every year, humans raise and eat 65 billion animals - nine animals for every person on the globe. In this eye-opening documentary, Michael examines the impact that this is having on the planet and finds out what meat eco-friendly carnivores should be buying.

Dr Michael Mosley seeks to establish the truth about meat. Are those barbecue favourites like burgers and sausages really that bad? Should we all go vegetarian instead?

Liz Bonnin presents a controversial and provocative episode of Horizon, investigating how new scientific research is raising hard questions about zoos - the film explores how and why zoos keep animals, and whether they need to change to keep up with modern science or ultimately be consigned to history.

Scientists are expecting a fit of violent activity on the sun which will propel billions of tonnes of superheated gas and pulses of energy towards our planet.

Volcanoes have long helped shape the Earth. But what is less well known is that there are volcanoes on other planets and moons that are even more extraordinary than those on our own home planet. Horizon follows an international team of volcanologists in Iceland as they draw fascinating parallels between the volcanoes on Earth and those elsewhere in the solar system.

For decades, some have suspected that there might be others out there, intelligent beings capable of communicating with us, even visiting our world. It might sound like science fiction, but today scientists from across the globe are scouring the universe for signals from extraterrestrials.

To answer the hottest question in nutrition, twin doctors Chris and Xand Van Tulleken go on month-long high-fat and high-sugar diets. The effects on their bodies are shocking and surprising.

A gas cloud three times the size of our planet has strayed within the gravitational reach of our nearest supermassive black hole. And across the globe, telescopes are being trained on the heart of our Milky Way galaxy, some 27,000 light years from Earth, in the expectation of observing this unique cosmic spectacle.

Professor Iain Stewart travels to Florida to try and understand what killed Jeff, and why the geology of this state makes it the sinkhole capital of the world.