Milky Way spiral gets an extra arm

摘要

The map of the Milky Way is being redrawn, following the discovery of another arm of the galaxy. The structure consists of an arc of hydrogen gas 77,000 light years long and a few thousand light years thick running along the galaxy's outermost edge. "We see it over a huge area of sky," says Naomi McClure-Griffiths of the Australia National Telescope Facility in Epping, New South Wales, who led the team that made the discovery.