At present, our Solar System is in its twentieth orbit of the Milky Way near the inner edge of a spiral feature known as the Orion Arm or, less poetically, the Local Arm. The ghostly arms are not permanent features of a disc galaxy like the Milky Way. Rather, they are concentrations of gas and dust where stars form, produced by disturbances within the Milky Way, or on occasions by a jolt from outside, such as a supernova or the passage of the Solar System through one of the dusty gas clouds that congregate in spiral arms.
Avi Shporer, Research Scientist, MIT Kavli Institute for Astrophysics and Space Research. A Google Scholar, Avi was formerly a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL). His motto, not surprisingly, is a quote from Carl Sagan: “Somewhere, something incredible is waiting to be known.”