Thursday, February 11, 2016

Globe at Night, Part 2

My son and I collected some more sky brightness measurements on the night of February 9, 2016 in the vicinity of the small town of Bedias, Texas. Bedias is located in a rural area, surrounded by flat pastureland. There are many areas with views down to the horizon, or nearly so. Regretfully, there are several light domes that spoil what would otherwise be a spectacular view. Still, the skies there are fairly dark, at least at zenith.

The following two images were taken with the same equipment and settings as those in the previous post.

For reference, here is an image of the Orion constellation taken from my house the same night as the Bedias trip:

Orion at the ObservaRory
This image was taken on a county road near the western edge of Walker County, just a few miles east of Bedias.

A few miles east of Bedias, Texas. The red line to the left was from a passing aircraft.
The light dome of Houston, Texas and surrounding cities dominated the sky to the southeast. The light dome of Huntsville was visible to the east, and Madisonville's light dome was barely visible to the north.

While not as dark overall as the sky near Weldon, the view was very nice, with many faint stars visible to the naked eye at zenith, and the Milky Way clearly visible.

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: