Jan 7, 2016

We Finally Know What’s Causing Galaxy Quakes

Posted by in category: cosmology

Did you need another existential risk to keep you up at night? Probably not, but here it is anyway: galaxy quakes. We’ve known about ‘em for years, and we hadn’t a clue what causes them—until now.

The culprit, unveiled today at the 227th meeting of the American Astronomical Society, is about as weird as you’d expect. Astronomers now believe that ripples in gas around the edge of the Milky Way are the result of a dwarf galaxy filled with dark matter ramming up against us several hundred million years ago.

Sukanya Chakrabarti of the Rochester Institute of Technology reached that bizarre conclusion by measuring the speed of three bright stars, called Cepheid variables, at the Gemini Observatory in Chile. These stars, which are suspected to hail from a larger population that entered our Milky Way during the Great Galactic Quaking of 300 million B.C., are all speeding away from us at about 450,000 mph.

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