Here's the latest article from the Astronomy site at BellaOnline.com.
Searching for extrasolar planets
There are pictures of fewer than two dozen planets orbiting stars outside the Solar System. But astronomers have discovered nearly six hundred of them. How do they find what they can't see?
This week I've gone to the edge of the visible universe and you can too. Virtually, of course, with a map.
It's probably impossible to grasp the immensity of the universe, but here's a website that tries to show us the visible universe on different scales.
It starts with a map of the stars within 12.5 light years of us. That's next door in astronomical terms, but a star that's 12.5 light years away is about 74 trillion miles away and its light takes twelve and a half years to reach us.
From the first map you can keep zooming out, each zoom expanding the map by 10-20 times. So you move out through the Milky Way and to the satellite galaxies. These are smaller galaxies gravitationally bound to our Milky Way. Further on is the Virgo Supercluster, which is made up of groups of galaxies which are gravitationally bound. This is really still our local area, as there are some ten million superclusters in the visible universe.
If you find it difficult to understand the map of the nearest stars, there is a helpful list which tells you their full names and some information about them. There is also a glossary at the end.
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Mona Evans, Astronomy Editor
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