OrbitNightA coffee?

Light pollution over Winston-Salem: how dark is the sky?

City lights glow up into the sky for up to 100 km. Tap the map or use your location: we add up every light around it from NASA's satellite picture and tell you what the night sky looks like there.

Winston-Salem

Adding up the lights around this spot…

Or tap anywhere on the map.

🌌 Nearest darker sky

No clearly darker sky within 150 km. Head for high ground with the lights at your back.

How we work it out

  • Satellite lights

    NASA's VIIRS satellite photographs the Earth at night: every lit town shows up.

  • 100 km around

    Each light is added in, weaker the farther it is (falling with distance to the power 2.5, as sky glow does).

  • Bortle class

    The total becomes the 1–9 Bortle class astronomers use, checked against dark-sky parks and city centres.

Lights from NASA's 2012 cloud-free night-lights composite (the one our classes are calibrated on): towns that have grown since may be brighter. An estimate, not a meter reading. Images: NASA Earth Observatory / GIBS

Another city

All 432 cities ⌄