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 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.
Your Own Copy
You can now add the World Sunlight Map gadget to either your own web page or Google's personalized home page. Here's an example of what it would look like on your web page:
Similar Products
For a continuously-updating desktop background of the Earth, grab a copy of xplanet for Windows, MacOS X, or Redhat Linux.
For a wall-hanging world clock with similar appeal, look at Geochron's expensive products.
Usage Guidelines
You may freely add the gadget via the Google-supplied<script src=""> tag to any web site.
If you have a use for the World Sunlight Map images that the gadget doesn't allow, contact me with details and we'll discuss other 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.
