World Sunlight Map: How it worksThe World Sunlight Map provides a computer-generated approximation of what the earth currently looks like. While less impressive than actually being into orbit, this is much more accessible to most of us.
I start with cloudless images of the earth during the day (from a pair of NASA satellites) and night (from a DoD program to map city lights). Every 3 hours, I download a composite cloud image based on data from weather satellites all over the world. And every half hour, these images are composited and mapped onto a sphere by xplanet according to the relative position of the sun. The flat maps are post-processed by ImageMagick to cut off the 15 degrees nearest the north and south poles where cloud data is unavailable.
For a continuously-updating desktop background of the Earth, grab a copy of xplanet for Windows, MacOS X, or Redhat Linux. For Ubuntu Linux, enable the Universe repository and install the "xplanet" and "xplanet-images" packages.
For a wall-hanging world clock with similar appeal, look at Geochron's expensive products.
Usage GuidelinesIf you have a use for the World Sunlight Map images, contact me with details and we'll discuss options. I don't charge for the use of the images, but I do want to make sure you minimize your use of my bandwidth and provide a link back to the World Sunlight Map wherever the image is used.