Galactic clusters Clusters of galaxies are the largest gravitationally bound systems in the universe. Some are 1015 solar masses. That´s 1,000,000,000,000,000 times the mass of the sun. Christine Jones describes how and why galaxies cluster. One famous cluster is the bullet cluster. Death Star Dan Evans has found two galaxies merging. Each hosts a supermassive black hole. One is sending out a jet of particles. This contradicts the earlier idea that black holes only swallow matter. Oscillating stars Most starts oscillate in some way. Detecting oscillations allows astronomers to see the properties of the inside of the star. Galaxy clusters can produce sound due to the diffusion of gas. One challenge is to try to explain why the hot gases don´t cool. The Chandra observatory The Chandra observatory was launched in 2000. Chandra can see way back to the beginning of the universe. X-rays show the hot violent events in the universe. Two merging galaxies, appear like a mess with an optical telescope. But using X-rays, black holes can be observed. And Chandra has shown two black holes heading straight for each other, lining up for one of the biggest bangs in the universe. John Wheeler - a tribute Physicist Paul Davies presents a profile of the great American theoretical physicist John Wheeler whose work gave us much of our knowledge about black holes, and indeed gave them their name. John Wheeler talks about his early fascination with the universe, his collaboration with Niels Bohr and his conversations with Albert Einstein. (first broadcast 13/09/2003) Café Sydney - changes after energy audit Café Sydney conducted an energy audit and changed the way it does business, producing large savings in energy use and costs.

[ Sat, 19 Apr 2008 00:00:00 +1000 ]

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