Milky Way galaxy and the Sun's orbit, computer artwork. The orange arrow marks the orbit of the Sun (yellow dot). The Milky Way is a spiral galaxy of over 200 billion stars, and it is about 100,000 light years across. The central region is a spherical bulge that contains mostly older, yellow stars. The spiral arms contain clusters of mostly younger, blue stars. The Sun is 28,000 light years from the galactic centre, taking about 220 million years to complete an orbit. The Sun is currently in the Orion Arm of the Milky Way, the faint arm seen between the larger two arms (Sagittarius Arm, inner; Perseus Arm, outer).