On the night of February 3, 2016, my son and I went on a little expedition to collect sky brightness measurements for the Globe at Night campaign. Globe at Night is a citizen-science project for raising public awareness of the effects of light pollution. Several times a year they host campaigns where participants observe a selected constellation and report how it appears in relation to a series of magnitude charts.
Our trip took us a few miles north of our house where, according to DarkSiteFinder.com, the sky brightness is rated around 3 on the Bortle scale.
The two images illustrate the difference in sky brightness between the ObservaRory (my house) and a location a little north of the town of Weldon, Texas. Both are 30-second exposures taken with a Canon EOS Rebel T3 with a 18-55mm zoom lens at 18mm (f/3.5) at ISO-1600. Both images are unprocessed, except to reduce their sizes.
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| Orion at the ObservaRory, about a mile north of the city limit of Huntsville, Texas. The sky here is around 4.5 on the Bortle scale. |
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| Orion north of Weldon, TX. The sky in this region measures 3 on the Bortle scale. Some of the light dome of Huntsville and a nearby prison unit are visible to the lower-left. Fainter objects, such as the Rosette Nebula, that are washed out by the skyglow in the previous photo are visible here. |
To learn more about light pollution and its effects on the environment, health, and energy consumption, I suggest the following links:
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