Thursday, February 4, 2016

Globe at Night

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, 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.

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.

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 me, the most striking thing about the second image is the darkness of the background sky--there is no nauseating soup of mercury and sodium lights washing out the stars.

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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