An astronaut aboard the International Space Station (ISS) photographed this sunset that looks like a vast sheet of flame. With the Earth's surface already in darkness, setting sun and cloud masses, and the sideways viewing angle make a powerful image, of the kind that astronauts like to take to commemorate their flights. Thin layers of lighter and darker blues reveal the many layers of the atmosphere above the lowest layer - the brown layer with its clouds and dust and smoke (known to scientists as the troposphere, the layer of weather as we experience it). It is the smoke and particles of dust in the atmosphere that give the strong red color to sunsets. Unlike most of us, astronauts see the atmosphere side-on, every 90 minutes, as in this view, with sixteen sunrises and sixteen sunsets every day. Astronauts often comment on how thin and fragile the Earth's atmosphere seems.