What is the polar night?

The answer

It is the winter period, called kaamos in Finnish, when the sun stays below or near the horizon in the far north. According to finland.fi it lasts almost two months in Utsjoki and four days in Sodankylä, and southern Finland has no polar night, though Helsinki's shortest day is still under six hours. The sky is not fully dark, because blue twilight often appears around midday and snow reflects the light.