Dark Sky Hunting with Google Earth
Wow! Ok, so you’re already aware how cool Google Earth is. Zoom in on your postcode, see your house from above, peer into neighbours’ windows using streetview… But did you know you can overlay images onto the Google Earth globe?
With this tool, and given a map of light pollution for a certain area, you can overlay a light pollution map onto your globe and zoom in to find which areas around the world have darker sites.
1. Download Google Earth http://earth.google.co.uk/ and install it on your computer
2. Download the appropriate light polution map:
Artificial Sky Brightness (Western Europe): http://www.lightpollution.it/download/eurv1.zip or
Naked Eye Star Visibility (Western Europe): http://www.lightpollution.it/download/OUTLIM_01_V2bordi%20TIF.zip
3. Unzip the file (both of the above links are zipped files of large .tiff images) to a suitable location
4. Open Google Earth, click on Add > Image Overlay
5. In the “Image Overlay” box enter a suitable title, such as “Naked Eye Star Visibility”, then browse to find the .tiff file you saved in step 3.
6. Move the transparency slider to between 25% and 50%
7. Click on the “Location” tab and enter these co-ordinates:
Artificial Sky Brightness map
N: 71° 8’30.67″N
Naked Eye Star Visibility map
This will overlay your Light Pollution maps onto the globe accurately (but you might want to tweak and fine tune to get the perfect fit – let me know if you get an even better fit than I did and I’ll adjust the co-ordinates above to match).
8. Click “OK” to finish. Now in your “Places” bar on the LHS you’ll see your overlays, with checkable boxes to enable / disable them.
Hints: I find it aesthetically more pleasing to disable Google Maps “Borders and Labels” in the “Layers” box
Happy Dark Sky Hunting!