Philadelphia, PA Night Sky Brightness
Philadelphia, PA's night sky, measured from orbit
Philadelphia's sky measures urban here. Sky glow overhead most nights. Typically only planets, the Moon, and a handful of the brightest stars are visible. Philadelphia's sky is brighter than 97.6% of the 3,206 cities in this dataset.
Note the source: a satellite reading of upward light, not a visual Bortle scale reading. The two measure related but different things, explained in the Bortle scale guide.
How far Philadelphia is from a meaningfully darker sky
The closest place in this dataset with a meaningfully darker sky is Collingswood, NJ, roughly 7 miles away in a straight line, rated suburban. Road distance will be more.
Collingswood, NJ is itself still a measured city, not a designated dark-sky park, this only compares against the 3,206 places this dataset covers.
How Philadelphia compares nationally
Philadelphia, PA has a population of about 1,573,916, one of 3,206 US cities of 10,000 or more residents in this dataset. Philadelphia's position, 3,110 of 3,206, darkest to brightest, comes from the sampling method the methodology guide sets out.