Explore the origins of our relationship with the skies. Our ancestors use the sky to navigate and tell time, and give religious significance to what they see in it. Then, a revolution gives birth to modern science.

What would it be like to go inside the mind of an animal? We have all gazed into a creature's eyes and wondered: what is it thinking about? What does it really know? Now, the revolutionary science of animal cognition is revealing hard evidence about how animals understand the world around them, uncovering their remarkable problem-solving abilities and exploring the complexity of their powers of communication and even their emotions. In this mini-series, NOVA explores these breakthroughs through three iconic creatures: dogs, birds and dolphins.

Follow the efforts to give the Earth a shape and a place. From flat Earth legends to Galileo's telescope, track major changes in scientific understanding. Ideas rise and fall as we continue to explore our ancient skies.

What would it be like to go inside the mind of an animal? We have all gazed into a creature's eyes and wondered: what is it thinking about? What does it really know? Now, the revolutionary science of animal cognition is revealing hard evidence about how animals understand the world around them, uncovering their remarkable problem-solving abilities and exploring the complexity of their powers of communication and even their emotions. In this mini-series, NOVA explores these breakthroughs through three iconic creatures: dogs, birds and dolphins.

Complete the puzzle of our ancient skies. A cast of scientific pioneers reshapes the solar system and better understands a growing universe. But there is still much more space to explore.

What would it be like to go inside the mind of an animal? We have all gazed into a creature's eyes and wondered: what is it thinking about? What does it really know? Now, the revolutionary science of animal cognition is revealing hard evidence about how animals understand the world around them, uncovering their remarkable problem-solving abilities and exploring the complexity of their powers of communication and even their emotions. In this mini-series, NOVA explores these breakthroughs through three iconic creatures: dogs, birds and dolphins.

From fruit flies to whales, virtually every animal sleeps. But why? Why do we need to spend nearly a third of our lives in such a vulnerable, defenseless state? Scientists are peering more deeply into the sleeping brain than ever before, discovering just how powerful sleep can be, playing a role in everything from memory retention and emotional regulation to removing waste from our brains. So why are we getting so little of it?

Scientists are coming to understand fat as a system akin to an organ — one whose size may have more to do with biological processes than personal choices. Explore the mysteries of fat and its role in hormone production, hunger and even pregnancy.

Emperor Qin Shi Huang of China was buried in a mausoleum with around 9,000 terracotta statues. Investigate how and why the life-sized figures were made and the technology behind the crossbows, spears and swords carried by the clay warriors.

For over 1000 years, chariots thundered across China's battlefields-dominating warfare longer than anywhere else on earth. Now, a series of amazing archaeological findings enable a team of experts to reconstruct and test China's first super-weapon.

Stunning new archaeological evidence provides clues about the Egyptians who built the Great Pyramid of Giza -- and how they did it. Join researchers as they delve into the logbook of a work crew and discover how the massive project transformed Egypt.

Following a trail of fossils found in all the wrong places — beech trees in Antarctica, redwoods and hippo-like mammals in the Arctic — uncover the bizarre history of the poles, from miles-thick ice sheets to warm polar forests teeming with life.

Horse riding played a key role in human expansion and civilization. But when and how did people first master these animals? Scientists use archaeology and genetics to uncover clues about the first horse riders and how they shaped the world.

Bioarchaeologists investigate a ninth-century mass grave in a rural English village. Will the remains unlock the mystery of the "Great Heathen Army," a legendary Viking fighting force that once invaded England?