How dark is the sky in Portsmouth, NH?

Portsmouth's sky measures suburban edge here. A noticeable glow near the horizon. Brighter stars and constellations are easy to pick out; the Milky Way is washed out. Portsmouth's sky is brighter than 28% of the 3,206 cities in this dataset.

Worth remembering: this is satellite radiance, not a ground observation. A true Bortle rating needs a human eye at night, this is the closest large-scale substitute.

The nearest darker sky to Portsmouth

14 miles from Portsmouth, straight-line, sits Somersworth, NH, the nearest city here with a darker sky than Portsmouth's own suburban edge band.

Somersworth, NH is itself still a measured city, not a designated dark-sky park, this only compares against the 3,206 places this dataset covers.

Portsmouth against the rest of the dataset

Portsmouth, NH has a population of about 22,938, one of 3,206 US cities of 10,000 or more residents in this dataset. Among all 3,206 cities here, Portsmouth ranks 894 from darkest to brightest, 1 being the darkest measured.