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Published on Jan 11, 2008
We can't see dark matter, and some skeptics doubt its existence, but many scientists think it makes up 20-some percent of our universe. Astronomer Doug Clowe explains how the Bullet Cluster, a group of galaxies billions of light years away, may shed some light on this mysterious stuff.
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Video podcast produced by Melissa Salpietra and Susan K. Lewis. Edited and narrated by Melissa Salpietra. Original footage and interviews produced by Julia Cort. NOVA is produced by WGBH in Boston. Funding for NOVA is provided by The DOW Chemical Company, David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and public television viewers.