M78, in the center of this image, covers an area north of Orion’s belt. At a distance of about 1,500 light-years, the bluish nebula itself is about 5 light-years across. Its blue tint is due to dust reflecting the blue light of hot, young stars in the region. (14 luminance images at 30 minutes & 6 images each of RGB color of 20 minutes each.)
More at http://madhuprathi.com/reflection-nebula-in-orion-m78/