This is a picture of Tucson taken here from the observatory. This shows the problem of "light pollution." All of the light you see here is making our observations harder, but it is also wasted electricity. The light coming up to the mountain does not help the good citizens of Tucson to see any better. The International Dark-Sky Association explains how you can help keep skies dark and save on electricity costs without having to sacrifice the lighting that we need around our homes.