Today, the topic of climate change is a major part of daily life, yet 40 years ago it was virtually unheard of. Since then, Horizon have followed scientists as they have tried to unpick how the climate works and whether it is changing. Dr Helen Czerski delves into this unique archive to chart the transformation of a little-known theory into one of the greatest scientific undertakings in history. It has been a constantly surprising journey of discovery that has revolutionised our understanding of climate, and seen scientists face unprecedented controversy and criticism.

Aliens almost certainly do exist. So why haven't we yet met E.T.? It turns out we're only just developing instruments powerful enough to scan for them, and science sophisticated enough to know where to look. As a result, race is on to find the first intelligent aliens. But what would they look like, and how would they interact with us if we met? The answers may come to us sooner than we imagine, for one leading astronomer believes she may already have heard a hint of their first efforts to communicate

There are 200 million insects for each of us. They are the most successful animal group ever. Their key is an armoured covering that takes on almost any shape. Darwin's stag beetle fights in the tree tops with huge curved jaws. The camera flies with millions of monarch butterflies which migrate 2000 miles, navigating by the sun. Super slow motion shows a bombardier beetle firing boiling liquid at enemies through a rotating nozzle. A honey bee army stings a raiding bear into submission. Grass cutter ants march like a Roman army, harvesting grass they cannot actually eat. They cultivate a fungus that breaks the grass down for them. Their giant colony is the closest thing in nature to the complexity of a human city.

The Greek tale of Jason and the Golden Fleece has been told for 3,000 years. It's a classic hero's quest tale - a sort of ancient Greek mission impossible - in which the hero embarks on a sea voyage into an unknown land, with a great task to achieve. He is in search of a magical ram's fleece, which he has to find in order to reclaim his father's kingdom of Iolkos from the usurper King Pelias. Michael Wood discovers a story of heroism, treachery, love and tragedy that would make Hollywood proud.

Michael Wood’s epic series moves on to the revolutionary years after 500BC - the Age of the Buddha. Travelling by rail to the ancient cities of the Ganges plain, by army convoy through Northern Iraq, and on down the Khyber Pass, he shows how Alexander the Great’s invasion of India inspired her first empire.

How should art depict the relationship between man and God? How can art best express eternal values? Can you and should you portray the face of Christ? For over 1,000 years these were some of the questions which taxed the minds of the greatest artists of the early West. In this three-part series, art historian Andrew Graham-Dixon sets out to unravel the mysteries of art from the pre-perspective era". In the first episode, Andrew traces the beginnings of Christian art in the declining Roman Empire, Egypt and medieval France, and reveals the ideas which lay behind the transition