Bones of the Milky Way

By Josh Roberts

We have peered far into the Universe and vastly expanded our knowledge of distant realms. But interestingly enough, we are still refining our understanding of our own place within our galaxy, the Milky Way. Research into this question follows in the footsteps of many great names in astronomy: from Herschel to Hubble, and from Kapteyn to Kant, generations of astronomers helped to establish our understanding of our place in space.

Imagine, if you will, trying to take a picture of the United States from somewhere close to the center of it. (That’s right. Lots of corn fields.) You would have no way to observe the entire country at the same time. Astronomers face a similar challenge in observing our home galaxy: we live within the disc of the Milky Way, a long way from the center (about 7,600 parsecs or 25,000 light years) and only a small distance from the middle of the plane (27 parsecs or close to 88 light years), with thick lanes of gas and dust blocking our view. We can see other more distant galaxies and have discovered many shapes and types, so comparing ourselves to them can help us determine the approximate shape and layout of the Milky Way.

Dr. Alyssa Goodman and her team recently realized that a dark cool cloud dubbed “Nessie” in the constellation Ara might have some secrets to tell about the Milky Way. We have seen similar features in other spiral galaxies: slightly denser tubes of material that define long spiral arms. By studying this “bone” of our galaxy, we may soon be able to refine our map of home to an even greater degree. We reside just far enough from the plane of the Milky Way’s disc that we could perhaps one day find the rest of these bones and create an even better layout of our place in space.

This concept and more appear in Goodman’s Authorea paper, currently in development now for later publication. Amazingly, you can to read the paper online while the authors finalize it! Talk about science in action…

Josh Roberts is a program presenter and astronomer at the California Academy of Sciences. He also contributes content to Morrison Planetarium productions.

Image: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)