YozoraAtlas

How dark is the sky in Beja?

Sky darkness for 3 towns and parks in Beja, worked out from NASA satellite images of light at night (2025). 2 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Guadiana Valley Natural Park (21.59, Bortle 4), the brightest Beja (19.68, Bortle 5). Milky Way season in Beja runs March to September: on moonless nights the bright core stands clear of the horizon, climbing to about 24° at its highest.

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 Beja with every place marked

Darkest skies in Beja

  1. Guadiana Valley Natural ParkBortle 421.59
  2. Southwest Alentejo and Vicentine Coast Natural ParkBortle 421.40

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 Beja

  1. BejaBortle 519.68

All 3 places in Beja

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Beja5Guadiana Valley Natural Park4Southwest Alentejo and Vicentine Coast Natural Park4