Pinwheel galaxy. Optical image of the Pinwheel galaxy (M33, NGC 598) in the constellation Triangulum. This face-on spiral galaxy is just under 3 million light years from our Milky Way galaxy, and is a major member of the Local Group of galaxies, which contains the Milky Way. M33 is about 60,000 light years across. It contains many prominent starbirth regions (pink). These huge emission nebulae glow as the hydrogen gas they contain is ionised by radiation from hot young stars within them. This image was produced using the Canada-France-Hawaii Telescope, Mauna Kea, Hawaii, USA.