Merging galaxies
A theory of galaxy formation — called the “bottom-up model” — says that large galaxies like the Milky Way attained their great size by swallowing up neighboring dwarf galaxies over billions of years. One in one hundred stars in the Milky Way belong to the stellar halo, which is much larger than the Galaxy’s familiar spiral disk. These stars are almost as old as the Universe. Many of the Milky Way’s ancient stars ancient stars, found in a stellar halo of debris surrounding the Milky Way, had been ripped from smaller galaxies by the gravitational forces generated by colliding galaxies.
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by admin on June 29, 2010
Supermassive black hole (image: NASA/JPL-Caltech)
If nothing, not even light, can’t escape, such an object is called a black hole. The black hole has no material surface. The original matter of the star is shrunk to an infinitely dense point, called a singularity. The perimeter of the black hole is called the horizon. Everything which could happen beyond the horizon is trapped, and can only increase the mass of the hole. But a black hole is not a monster: it can only catch objects which come very near. If we replaced the Sun with a black hole, we hardly notice the difference.
There are fourth basic types of black holes:
1. Stellar black hole. It forms when a massive star runs out of nuclear fuel and collapses under its own weght (supernova). [click to continue…]
Watching vodcasts discover the beauty of universe (image by Inga Nielsen)
Video podcasting, or vodcasting, is the latest evolution of the podcast revolution and has become a competitor for traditional television. It is a digital recording made available on the Internet for downloading to a personal video player or a computer. Gateways like the iTunes and video community websites such as YouTube have created new content markets. Of all the sciences, astronomy is the most visual and is responsible for some of the most memorable images of our time. Video is a natural medium for astronomy communication because of the readily available image, illustration, and animation resources for production. The online distribution of vodcasts (video podcasts) offers significant advantages over the shipping of more traditional physical audiovisual products like DVDs. Digital products – vodcasts – are available on demand when the user needs them. To watch the feeds on your computer, you need to download vodcasting software (iTunes, Quicktime or Juice), and subscribe to an RSS feed offering vodcasts.
Astronomind will help you too discover top 10 video podcasts of the best astronomy and space exploration web sites :
10. Sky and Telescope Media’s Channel on Youtube. Huge numbers of amateur astronomers flocke to the annual Northeast Astronomy Forum to sample the wares at one of the world’s largest telescope shows. You can whatch some video about new astronomy equipment (Meade, Celestron, Apogee etc.).
9. Astronomy magazine videos. The editors of the magazine bring you the latest science, new products, hobby tips, and more.
8. Physics central vodcasts help to learn how the world and universe work. The American Physical Society’s website represents some 45,000 physicists. It describe the latest research and the people who are doing it. Enjoy the sights and sounds of physics with our podcasts and videocasts, always fun and always engaging – just like physics. [click to continue…]
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