Description

This 18×24-inch map shows the duration of the longest nights of the year in North America by latitude.

Overview

For most places, the longest night occurs on the Winter Solstice (December 21 or 22). The long night shortens to around 12 hours as we approach the Equator. However, at the Equator, the longest night happens twice, both occurring on the Equinoxes. Each lasts about 11 hours and 54 minutes.

From around the Equator to just beyond the Arctic Circle (66.5°N), the longest night doubles from 12 to 24 hours. Polar Night (over 24 hours of darkness) actually begins just beyond the Arctic Circle at 67.5°N. This phenomenon is due to the refraction of sunlight by the atmosphere. At the next tenth of a degree north latitude (67.5°N), the longest night triples to 72 hours! At 67.6°N, the longest night jumps to 11 days! By 68°N, the longest night is nearly a month long, at 26 days. Contrary to popular belief, the approximately 6-month period of darkness occurs only at the poles. Since we live on a spherical object, the inverse occurs at the Summer Solstice in June.

Map Details

This map is an 18×24 in page size printed on 170 gsm paper.