Milky Way may indeed have four spiral arms

By Ashley Yeager, 11:13 AM December 17, 2013

In 2008, the Milky Way lost two of its four major spiral arms, according to some analyses. But the galaxy may be getting them back.

Radio telescope data from the 1950s first suggested that the galaxy had four arms. But observations from NASA's Spitzer Space Telescope reported in 2008 knocked the number of major arms down to two. Spitzer looked at cooler, longer-living, lower-mass stars like the sun that can be tugged toward the center of the galaxy.

But a new survey of massive stars throughout ...

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