“Milky Way Orbit 19” –Extinction by Spiral-Arm Apocalypse

    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 … Continue reading “Milky Way Orbit 19” –Extinction by Spiral-Arm Apocalypse