"With the extreme cold, ice crystals filled the air," says photographer Peter Rosén in downtown Stockholm. "This created a magnificent display of #light #pillars that looked almost like Northern Lights."

Light pillars are #manmade lights spread into colorful columns by large wobbly snowflakes and other crystals. No solar activity is required. The only ingredients are ice and light #pollution.

The red lights in Rosén's photo are aircraft warning beacons on tall buildings and construction cranes. Other colors correspond to high pressure sodium lamps (warm orange) and modern LED lamps (blue-white).

https://spaceweather.com/