Just 92 elements made up the world, but the belief that were only four - earth, fire, air and water - persisted until the 19th Century. Professor Al-Khalili retraces the footsteps of the alchemists who first began to question the notion of the elements in their search for the secret of everlasting life.He reveals the red herrings and rivalries which dogged scientific progress, and explores how new approaches to splitting matter brought us both remarkable elements and the new science of chemistry.

In part two, Professor Al-Khalili looks at the 19th century chemists who struggled to impose an order on the apparently random world of the elements. From working out how many there were to discovering their unique relationships with each other, the early scientists' bid to decode the hidden order of the elements was driven by false starts and bitter disputes. But ultimately the quest would lead to one of chemistry's most beautiful intellectual creations - the periodic table.

In the lush expanse of the Ngogo territory of Uganda, a chilling discovery sends ripples through the chimpanzee community: a chimp has been killed. As the investigation unfolds, it becomes clear that only one other group could be responsible for such a brazen act. As whispers of war grow louder, the Ngogo community braces itself for impending conflict. Will the Ngogo community overcome this threat? Or will the heart of their empire be torn apart? Find out in this gripping episode.
'Others' delves deep into the intricate social structures, alliances, and rivalries of our primate relatives, offering a gripping and emotional journey into the heart of the jungle. This is not just a tale of survival but a testament to the complexity of chimp society. Join us and witness the raw and untamed world of the chimp empire.

The tale of the strongest superhero in Greek mythology and his quest for redemption. To atone for committing a heinous crime, Hercules embarks on a series of impossible challenges known as the 12 Labors. Hercules endures as one of history's most influential demi-Gods, but recent archaeological discoveries suggest that mythology's strongest man may have been inspired by a real person.

Idolized in ancient Norse mythology as the protector god, Thor battles evil ogres and a giant serpent bent on destroying mankind. It's the quintessential fight for survival that culminates in a final showdown between good and evil. But was the rise and fall of the hero Thor ancient code for something greater? Today, new discoveries unlock the hidden truth behind the Norse god of Thunder. Able to wield thunder from his hammer, Thor was the most revered of the Norse gods, from fending humanity from the giants that brought calamity, to his pursuit of the Midgard Serpent. Though, his fate is told to sealed during Ragnarok, it is actually the invasion of Christianity that proves far more damning to this mighty god.

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.