Bok globules in nebula NGC 281, optical image. This nebula is a region of star birth, and the bright spots are Bok globules, or clouds of gas condensing to form stars. The reddish area is an emission nebula, where radiation from the hot, newly formed stars ionises the surrounding gas and causes it to glow. The dark patterns across the nebula are caused by dark dust clouds in the foreground that obscure the light from behind. The nebula lies in the constellation Cassiopeia, around 10,000 light years from Earth. This image was taken by the Hubble Space Telescope (HST).