The Earth at Night
(And other views of our planet)
Individuals (e.g. David Hastings) and organizations (e.g. NOAA, NASA) have made available several rectangular maps of the earth based on satellite images. We use Partiview as a viewer for these maps, resulting in easy-to-use interactive globes. Installation (on Windows) is just a matter of downloading the zip file associated with each map, opening it in a new folder, and then clicking on a batch file, i.e. files with a .bat extension. Batch files with _geowall in the name work on GeoWalls.
Instead of downloading all the zip files below separately, you could get them all in one big (17Mb) file earthviews.zip.
Navigation: 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.
Earth At Night
This uses the Earth City Lights map from the NASA Visible Earth site.
Download earthatnight.zip (2 Mb) click on earthatnight.bat or earthatnight_geowall.bat and you get the picture below. (Linux instructions: type "./earthatnight.bat" or "./earthatnight_geowall.bat" from the command prompt.)
In general, brightness is proportional to population density, lights = cities, and brighter lights = larger cities. Brightness isn't just directly proportional to population density; but also to the population's wealth. Wealthier folks (e.g. compare the United States and India; better yet, North and South Korea) can afford to spend more money on lighting.
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.
You can clearly see where people prefer to live; by rivers (Nile, Amazon), railways (Trans-Siberian in Russian), coasts (Mediterranean in South Europe), etc.
Earth during the Day
Height, above and below sea level, is coded by color. The topography map comes from the National Geophysical Data Center at the National Oceanic and Atmospheric Administration.
Download topo.zip (1Mb), click on, or type, topo.bat or topo_geowall.bat
Last Ice Age
This map comes from the National Geophysical Data Center at the National Oceanic and Atmospheric Administration.
Download iceage.zip (5Mb), click on iceage.bat or iceage_geowall.bat and you see what the earth looked like during the last ice age about 18 000 years ago. Notice how Siberia and Alaska are joined, Britain and Sri Lanka and Indonesia aren't islands, the Red and the Med are lakes rather than seas, etc. This is a topographic map as well, hence the color of Antarctica.
If you click on iceagetoday.bat then you can clearly see how the extra landmass above comes from the shallower parts of the seas and oceans; in fact the map was created based on evidence that the sea level was 110 m lower 18 000 years ago. You can toggle between maps of the earth yesterday and today by clicking on the first button.
This map also comes from the National Geophysical Data Center at the National Oceanic and Atmospheric Administration.
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