Philadelphia Stargazing & Astronomy Report

Key Sky Quality Metrics

SQM (mag/arcsec²)

16.98

Bortle class

Class 9 (Class 9)

Darkness Quotient

16%

Dataset

April 2026

Inner city sky

Philadelphia: The Practical Verdict

As a major US city in Pennsylvania, Philadelphia suffers from extreme levels of light pollution due to its dense urban environment and its proximity to other bright urban centres like New York to the north-east. This results in a severe urban sky with the Milky Way not visible and the night sky's faintest objects overwhelmed by the city's pervasive brightness.

From within Philadelphia, your best options will be the Moon and bright planets, alongside prominent stars and double-star systems. Narrowband imaging could capture details in bright nebulae, but visual deep-sky observing or broadband imaging is nearly impossible under these conditions. The west-north-west offers the darkest horizon, although the improvement is limited.

For those willing to travel, a modest improvement in viewing conditions can be found around 155 km south-south-west at Williamsburg, Maryland. However, exceptional clarity would require even longer drives beyond 300 km.

At a Glance

Overall

Severe urban sky - This is a severely light-polluted urban sky. Only the Moon, planets, bright stars, and a few specialist targets remain practical.

Milky Way

Not visible - The Milky Way is not visible from this sky.

Best targets from here

Moon, planets, bright stars, double stars, solar system events, narrowband imaging only with care

Do not prioritise

visual deep-sky observing, broadband galaxies, reflection nebulae, widefield Milky Way

Limited nearby upgrade

Williamsburg, Maryland is the strongest nearby option but remains Bortle 5; the improvement is real but modest.

Good dark window

Philadelphia's longest dark windows fall in December and January, with the shortest nights around June and July. Plan deep-sky sessions around the autumn and winter months for the best combination of long nights and true astronomical darkness.

Frequently Asked Questions

Can you see the Milky Way from Philadelphia?

No. Philadelphia is a Bortle Class 9 sky with SQM 16.98, so the Milky Way is not visible from the city. For Milky Way photography, look for a Bortle 4 or darker site.

What Bortle class is Philadelphia?

Philadelphia is Bortle Class 9 (SQM 16.98), a severe urban sky for astronomy.

Is Philadelphia good for stargazing?

Not for serious deep-sky observing. Philadelphia is a severe urban sky where the Moon, planets, and a handful of bright targets are the realistic options from the city itself.

Is Philadelphia good for astrophotography?

Broadband deep-sky imaging is heavily compromised from Philadelphia and a Bortle 4 or darker site is strongly recommended. Even narrowband imaging is difficult from Philadelphia without careful processing.

What can you observe from Philadelphia?

Primary targets from Philadelphia include Moon, planets, bright stars, double stars, solar system events. Targets such as visual deep-sky observing, broadband galaxies, reflection nebulae are not realistic from this sky.

Where are darker skies near Philadelphia?

The closest meaningfully darker mapped site is Woodland Township, New Jersey, about 52 km east of Philadelphia, reaching Bortle 7.

When is the sky darkest in Philadelphia?

The sky over Philadelphia is darkest around January, December.

Is light pollution in Philadelphia getting better or worse?

Long-term light pollution over Philadelphia has been broadly stable across the available measurements.

• Byram, New Jersey

  Direction

  E

  Distance (km)

  52.8

  SQM

  19.70

  Bortle

  6

• Woodland Township, New Jersey

  Direction

  E

  Distance (km)

  51.8

  SQM

  19.54

  Bortle

  7

• Doughty, New Jersey

  Direction

  SSE

  Distance (km)

  60.8

  SQM

  19.61

  Bortle

  6

• 24, Maryland

  Direction

  SW

  Distance (km)

  89.5

  SQM

  19.72

  Bortle

  6

• Ryan Township, Pennsylvania

  Direction

  NW

  Distance (km)

  119.9

  SQM

  20.05

  Bortle

  6

• Williamsburg, Maryland

  Direction

  SSW

  Distance (km)

  154.9

  SQM

  20.53

  Bortle

  5