YozoraAtlas

How dark is the sky in Maryland?

Sky darkness for 12 towns and parks in Maryland, worked out from NASA satellite images of light at night (2025). 1 of them has skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Assateague Island National Seashore (21.25, Bortle 4), the brightest Baltimore (16.80, Bortle 8).

19 Bortle class, 1 pristine to 9 city center park or dark-sky place city

Numbers like 21.95 or 16.97 are the brightness of the sky overhead on a clear, moonless night, in mag/arcsec². The scale runs backwards: a lower number means a brighter sky, from about 22 for a natural sky to about 17 in a city center.
How the readings are made

NASA satellite night-lights map of Maryland with every place marked

Darkest skies in Maryland

  1. Assateague Island National SeashoreBortle 421.25

Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.

Brightest city skies in Maryland

  1. BaltimoreBortle 816.80
  2. DundalkBortle 817.32
  3. Silver SpringBortle 817.59
  4. TowsonBortle 817.70
  5. Glen BurnieBortle 817.71

All 12 places in Maryland

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Assateague Island National Seashore4Baltimore8Bowie8Columbia8Dundalk8Frederick8Germantown8Glen Burnie8Rockville8Silver Spring8Towson8Waldorf7