... The spiral galaxy spans about 100 thousand light-years and is seen almost exactly edge-on from our perspective. ... Scorpius in Red and Blue . ... Cosmic dust clouds dim the light of background stars. ... Since bright stars tend to radiate strongly in the blue portion of the visible spectrum, and the interstellar dust scatters blue light more strongly than red, the dusty reflection nebulae tend to be blue. ... How much of Jupiter's moon Europa is made of water? ... A Close Pass of Saturns Moon Dione...