After 665 weightless days in space, NASA's most experienced astronaut, Peggy Whitson, smashes through the atmosphere on her last journey home to planet Earth. With unprecedented filming on board the ISS during Peggy's final mission and with the support of our other featured astronauts, we reveal how their time in space transforms their understanding of our planet's wonders, insights that will change our perspective, too. There is no place like home. Or is there? Just how strange is our rock, and is it really unique in the universe? Astronaut host – Peggy Whitson.
2018 • Astronomy
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.
Forget the big bang. The real moment of creation was the Cosmic Dawn - the moment of first light. This is the scientific version of the story of Genesis. The big bang gets all the credit for creating our universe. But in fact, the universe it gave was dark and boring. There were no stars, no galaxies, just a vast, black fog of gas - the cosmic dark ages. But, after a hundred million years of nothing, came a dramatic moment of transformation - the Cosmic Dawn. It's the moment the first stars were born, the moment that lit up the Universe, and made the first structure and the first ingredients of life. This was the real moment of creation. Astronomers are now trying to witness the cosmic dawn. For the first time they have the tools to explore the very first stars of the universe and to tell the scientific story of our creation.
Dallas Campbell looks back through almost 50 years of the Horizon archives to chart the scientific breakthroughs that have transformed our understanding of the universe. From Einstein's concept of spacetime to alien planets and extra dimensions, science has revealed a cosmos that is more bizarre and more spectacular than could have ever been imagined. But with every breakthrough, even more intriguing mysteries that lie beyond are found. This great journey of discovery is only just beginning.
Before moving on from Jupiter to Saturn, we’re going to linger for a moment on Jupiter’s moons. There are 67 known moons, and 4 huge ones that we want to explore in greater detail. Ganymede is the largest - larger, in fact, than any other moon in the solar system and the planet Mercury! Callisto, orbiting the farthest out, is smaller but quite similar to Ganymede in many ways. Io, meanwhile, is most noteworthy for its tremendous volcanic activity. There’s also water on Ganymede and Europa!