How big, how old, and how dense is the Universe?
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An exploration by Jeff Vogtschaller
University of Wisconsin, Madison
For his Sauk County 4-H Astronomy Project
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How do
astronomers know how far away all those exotic stars and galaxies are,
how can they tell there are planets around other stars,
and how do we know the universe is expanding?
The answer to these questions is all the same!
What would you like to know about?
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