The reflection nebula M78 in Orion, shown in an R-band CCD image obtained with the UA 16-inch telescope. The field of view shown is 26 arcminutes wide. This cloud lacks the hot stars to ionize its hydrogen, so we see it only as the dust particles scatter light from embedded stars. M78 lies about 2.5 degrees northeast of the trailing star in Orion's belt, ζ Orionis or Alnitak. It would show up somewhat more clearly in a blue-filtered image, since reflection nebulae are bluer than their illuminating stars for the same reason that our daytime sky is bluer than sunlight.
Last changes: 7/2006 © 2006