This image shows radio light in Andromeda’s central region. The year man first walked on the Moon, 1969, was also the year that radio continuum emissions were detected in Andromeda’s spiral arms. The radio emissions seen here are a mix of both thermal and nonthermal. To separate the two, scientists make observations at different wavelengths. At the center of Andromeda—and also at the center of this image—is a light blue mass with a bright, intense core. This radio source’s dimensions vary depending on the wavelength, but at 20 centimeters it measures 8 to 10 arc minutes across (about 5,400 light years). The two pale lines of emission on either side of Andromeda’s center originate in the galaxy’s spiral arms.