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View Full Version : Ep. 97: Galaxies



Fraser
2008-Jul-15, 06:00 PM
This week we're going to look at some of the biggest objects in the Universe: galaxies. It was the discovery of galaxies in the early 20th century that helped astronomers realize just how big the Universe is, and how far away everything is. Let's learn how galaxies formed and how they evolve and change over time, merging with the neighbors. And what the future holds.http://feeds.feedburner.com/~r/astronomycast/~4/336292124

More... (http://feeds.feedburner.com/~r/astronomycast/~3/336292124/)

page13
2009-Jan-20, 06:31 AM
Pamela mentions (@ 19:30 min) that when a galaxy passes a larger one, its gas, dust and a few stars get sucked out which causes the smaller galaxy to shift from blue to red. Why?

Empyre
2009-Jan-21, 01:27 AM
Blue stars don't last very long, just several million years, which is very brief compared to the average lifespan of yellow and red stars. Because of this very short lifespan, blue stars are only found where new stars are being formed. If all the gas and dust is sucked out of a galaxy, no more new starts will be formed, and when the blue stars burn out, only the redder, longer-lived stars will be left. That's what she was talking about when she said the galaxy would become redder.

page13
2009-Jan-26, 06:09 PM
perfect, thank you Empyre. I didn't realize the 'blue phase' was so short.