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Comet C/2011 L4 (PANSTARRS)

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Comet C/2012 S1 (ISON)

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Web Extras

The curious matter of the missing matter

Scientists still can't account for about 40 percent of the stuff of stars, planets, and people.
By Daniel Pendick
Published: February 23, 2009
Some 23.3 percent of the cosmos exists in the form of dark matter, while 72.1 percent — according to the latest and most precise measure — is dark energy. The nature of dark matter and dark energy remains a mystery. But surprisingly, so does much of the universe's normal, or "baryonic," matter — the stuff, like you and me, made of protons and neutrons.
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