XMM-Newton and Chandra help revise distance to Milky Way's outer spiral arms
The European Space Agency's XMM-Newton and NASA's Chandra X-ray space telescopes have spotted the aftermath of three bright explosions echoing through the outer spiral arms of our galaxy, the Milky Way. By measuring the distance to these echoes, they found the outer arms to be up to 10% farther away...
Originally published at Phys.org