Milky Way may get an extension

A new study suggests the Milky Way doesn’t need a makeover: It’s already just about perfect.

Astronomers base that assertion on their discovery of a vast section of a spiral, star-forming arm at the Milky Way’s outskirts. The finding suggests that the galaxy is a rare beauty with an uncommon symmetry — one half of the Milky Way is essentially the mirror image of the other half.

Thomas Dame and Patrick Thaddeus of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., say the structure they’ve discovered is most likely the outer ex