When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…

For as long as people have walked the Earth, they have looked to the stars, have been inspired by their beauty and remoteness and have found their way over sea and deserts by their guidance. Since then, enormous progress has been made in the understanding of the stars, and today the expanding and fascinating world of high-energy astronomy awaits…