Desktop Earth is a wallpaper generator for Windows. It runs whenever you log into your computer and updates your desktop's background with an image that accurately represents the Earth as it would be seen from space at that precise moment in time.
Images are rendered from high-resolution textures (2560 x 1280) for any size monitor. There is an image for every month to accurately depict snow and foliage changes. The imagery is based on NASA's Blue Marble Next and Earth's City Lights.