The NASA Blue Marble site has a wonderful shot of the earth at night. However, it's just a rectangular map. It's much nicer to play with it as a globe - and now you can! Either on your personal computer or on a GeoWall.
Windows: Download earthatnight_win.zip (2 Mb) and unzip it in a new directory. There are two batch files in this directory. Clicking on earthatnight.bat starts up the regular version, clicking on earthatnight_geowall.bat starts up the GeoWall version.
Linux: Download earthatnight.zip (1.7Mb). Make a new directory somewhere, and go there. Unzip this file there, and type
This should come up with two windows. One is a command window, and one has a globe with the picture of the sky at night. You only want the latter, so you can close the former.
If you are running a GeoWall system, type
The trick is to hold the mouse button down while moving. Navigation is inertia-based (this is a feature, not a bug!), so the scene keeps moving when you let go of the mouse button, depending on how fast you were moving the mouse when you let go. Move-click with the left mouse button to rotate, with the right mouse button to zoom.
In general, brightness is proportional to population density, lights = cities, and brighter lights = larger cities. Lights in oceans are islands. However, the lights on islands often seem much larger than the population on the islands indicate, so perhaps the Blue Marble folks touched them up or the water around the islands has some kind of reflective effect. Remember that this is a satellite image.
Some things to look out for
Dinoj Surendran, an intern of the Cosmus section of the SCOPE Museum Exhibit Design Project, compiled this visual. He thanks Selden Ball for documenting the Partiview commands needed to do this, and Stuart Levy for adding the focalpoint command to Partiview to make it work that software work on a Geowall.