What the night sky looks like over Alton, IL

Alton's sky measures suburban here. Light dome dominates much of the sky. Only the brightest stars and planets stand out clearly. That's brighter than 65.5% of the 3,206 US cities in this dataset.

The number comes from orbit, not a stargazer's logbook, so treat it as an estimate of sky glow rather than a certified Bortle class.

The nearest darker sky to Alton

5 miles from Alton, straight-line, sits Godfrey, IL, the nearest city here with a darker sky than Alton's own suburban band.

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

Alton against the rest of the dataset

About 24,967 people live in Alton, IL, sized enough to appear in this dataset of 3,206 incorporated US cities. Among all 3,206 cities here, Alton ranks 2,091 from darkest to brightest, 1 being the darkest measured.