Milky Way Mosaic of photographs of the Milky Way the spiral galaxy in which our solar system lies Our Sun is believed to be around twothirds of the way out from the centre in a small spiral arm Galactic Centre lies at the centre of the image in the constellation Sagittarius This is where the bulge of stars in the Milky Way is at its greatest tapering away on either side The image runs around the whole of the sky so our view away from Galactic Centre is seen both at far left and at far right Interstellar dust obscures much of the Galaxys central axis The Milky Way is thought to be about light years across and to contain over billion stars