Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. These bright stars, newly condensed from gas and dust clouds, give away the location of the spiral arms they are born in. Dying and fading before they move too far from their birth place they make excellent tracers of spiral structure. From left to right the galaxies are known as M33, M74, and M81 and have progressively more tightly wound spiral arms. Astronomers would classify these as Scd, Sc, and Sb type spirals using a galaxy classification scheme first worked out by Edwin Hubble .
Specific rights apply.