Just as there are bones in your arms, there are bones in our galaxy's arms as well - and researchers using NASA's Spitzer Space Telescope have shared the x-rays to prove it.
All right, they're not actually x-rays but rather images made from observations in infrared light, which Spitzer is specifically designed to detect. (One does need to clarify such things in astronomy.) Orbiting Earth over 172 million kilometers away Spitzer can see infrared radiation that isn't visible from the ground, radiation that's emitted from anything in the Universe warmer than 0 Kelvin.
The image above, looking into the plane of the galaxy, shows a long thin strand of dark, cold material stretching between two brighter regions in the lower half - this is a segment of what's being called a "bone" of the Milky Way, a part of the vast skeletal structure that forms its framework.
It's the first image of such a structure within our own galaxy.
"This is the first time we've seen such a delicate piece of the galactic skeleton," said Alyssa Goodman, lead author of the study from the Harvard-Smithsonian Center for Astrophysics. Goodman presented the discovery during the 221st meeting of the American Astronomical Society in Long Beach, CA on January 8.