The Darkest Skies
in Wyoming

"Sky quality measurements were recorded at West Road in Devils Tower NM on 9/6/2005. The site demonstrated a scientific darkness reading of 21.96 SQM."

"Smoke haze on the western horizon due to wildfires in Idaho, causing elevational extinction coefficients. Night was calm and clear. Computer issues only allowed one set of data to be taken for the night. SQM 21.6"

"Sky quality measurements were recorded at Missouri Butte 1 in Devils Tower NM on 7/20/2006. The site demonstrated a scientific darkness reading of 21.87 SQM."

"Smoke plume to west, some high cirrus, transparency fair. Second set best of night"

"Horizon blocked. Borlte 3 due to city lights beyond canyon wall."

"Some equipment issues during the night with both camera sets that were being used (ML4 and IMG2). There are lots of local glare sources from nearby ranches and NPS maintenance facilities. Huge railyard facility for transporting coal located to the west near Guernsey creates its own light dome from the excessive yard lights (very tall light pole installations). The town of Fort Laramie has a few bad sections of lighting that are readily visible from the park. Even with all of this surrounding light pollution, the night skies here are very good. Rich detail visible in the Milky Way (which extends almost horizon to horizon). A new "load-out" rail facility is being built almost adjacent to the park boundary on the NE."

"No cars at this site, easier to dark adapt. SQM 21.7. Headlights reflecting off truck camper"

"Sky quality measurements were recorded at Union Pass in Shoshone NF on 8/21/2017. The site demonstrated a scientific darkness reading of 21.58 SQM."

"Clear night with fair transparency above 20 degrees. Haze visible along the horizon. Seeing fair. Local light from the reservation was direct glare, while the light dome from Hardin was the largest. Billings and Sheridan light domes visible but not bright. Overall the direct glare was distracting, but blocking this allowed for dark adaptation. Milky Way was easily seen with detail in sagittarius, and dust lanes. Visible from tail of Scorpius in South to Cassiopeia. SQM 21.64 at 0130; SQM-L 21.63 at 0152."

"Very dark sky. The Milky Way can be seen all the way up to about 10 degrees above the horizon. Most of the light domes along the horizon are small and faint. Zenith appears to be in its natural condition."