Does Dark Matter Encircle Earth?

Dark matter is five times as abundant as normal matter in the universe. But it continues to be an enigma because it is invisible and nearly always passes right through normal matter. Astronomers only found out about dark matter by inferring its presence from the gravity it exerts—notably, it keeps spinning galaxies from flying apart. Rather than peering at distant galaxies to study it, though, astronomers might want to look closer to home: dark matter could be exerting measurable effects in our own solar system.
Specifically, investigators should target Earth and the moon, insists theoretical physicist Stephen Adler of the Institute for Advanced Study in Princeton, N.J. If the mass of Earth and the moon when measured together seems greater than their masses separately, he explains, the difference could be attributed to a halo of dark matter in between.

Full story on Scientific American



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