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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.
Discoveries of new planets have revealed countless worlds much stranger than Earth. Some of these strange worlds don't have stars; others are made out of diamonds. Will we ever find a planet like Earth, or are these distant worlds stranger than fiction?
S5E9 • How the Universe Works • 2017 • Astronomy
In summer 2013, the black hole at the centre of the Milky Way was getting ready to feast. A gas cloud three times the size of our planet strayed within the gravitational reach of our nearest supermassive black hole. Across the globe, telescopes were being trained on the heart of our galaxy, some 27,000 light years from Earth, in the expectation of observing this unique cosmic spectacle. For cosmic detectives across the Earth, it was a unique opportunity. For the first time in the history of science, they hoped to observe in action the awesome spectacle of a feeding supermassive black hole.
On the 15th Dec 2015, Tim Peake will launch into space to be Britain's first astronaut on board the International Space Station. For the past two years, Tim has been filming a video diary for Horizon showing the risks, pressures and rigorous training required to launch into space. Horizon also talks exclusively to his wife and two children as they prepare to wave him goodbye on his voyage to space. From training in the Soyuz capsule, centrifuges, space station mockups, virtual reality and a huge pool to replicate spacewalks, to dealing with the physical dangers of weightlessness, witnessing his first launch and spending time away from his wife Rebecca and his two sons, this is an intimate portrait and remarkable insight into the world of an astronaut.
Last week we covered multiple star systems, but what if we added thousands or even millions of stars to the mix? A star cluster. There are different kinds of clusters, though. Open clusters contain hundreds or thousands of stars held together by gravity. They’re young, and evaporate over time, their stars let loose to roam space freely. Globular clusters, on the other hand, are larger, have hundreds of thousands of stars, and are more spherical. They’re very old, a significant fraction of the age of the Universe itself, and that means their stars have less heavy elements in them, are redder, and probably don’t have planets (though we’re not really sure).
35 • Crash Course Astronomy • 2015 • Astronomy
Carl Sagan talks about religion and the universe
3/10 • The Sagan Series • 1989 • Astronomy