To determine the true age of the Earth, geochemist Clair Patterson developed the uranium-lead dating method to make an unprecedented discovery - calculating Earth's age of 4.5 billion years. But Patterson's groundbreaking discoveries were just beginning. Patterson made it his mission to draw public attention to the detrimental effects of lead in the environment and dedicated his career to fighting against the petroleum and chemical industry, eventually achieving public health's biggest victory of the 20th century.
The inner planets, Mercury and Venus, orbit closest to the Sun, making them literally an Inferno of heat. NASA and other space agencies have attempted to learn more about these rocky planets. Follow the plucky probes that attempted to decipher the secrets of the Solar System's inner circles of hell.
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. Through the team's research, we discover that the largest volcano in the solar system - Olympus Mons on Mars - has been formed in a similar way to those of Iceland, how a small moon of Jupiter - Io - has the most violent eruptions anywhere, and that a moon of Saturn called Enceladus erupts icy geysers from a hidden ocean. Computer graphics combined with original NASA material reveal the spectacular sights of these amazing volcanoes. Along the way, we learn that volcanoes are not just a destructive force, but have been essential to the formation of atmospheres and even life. And through these volcanoes of the solar system, scientists have discovered far more about our own planet, Earth - what it was like when Earth first formed, and even what will happen to our planet in the future.
Today we’re rounding out our planetary tour with ice giants Uranus and Neptune. Both have small rocky cores, thick mantles of ammonia, water, and methane, and atmospheres that make them look greenish and blue. Uranus has a truly weird rotation and relatively dull weather, while Neptune has clouds and storms whipped by tremendous winds. Both have rings and moons, with Neptune’s Triton probably being a captured iceball that has active geology.
The worlds that surround our planet are all made of rock, but there the similarity ends. Some have a beating geological heart, others are frozen in time. Professor Brian Cox travels to the tallest mountain on Earth, the volcano Mauna Kea on Hawaii, to show how something as basic as a planet's size can make the difference between life and death.