World Sunlight Map: How it works
The 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 day, 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.
Similar Products
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 Guidelines
If 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.
