Utqiaġvik, the northernmost city in the United States, experienced its last sunset of the year on Wednesday, November 19, 2023. The sun dipped below the horizon at 1:30 p.m.
local time, marking the start of the polar night, a period of continuous darkness that lasts for more than two months.
The polar night is a natural phenomenon that occurs only inside the polar circles, where the sun stays below the horizon for more than 24 hours. The opposite phenomenon, the polar day or midnight sun, occurs when the sun remains above the horizon for more than 24 hours.
Utqiaġvik, formerly known as Barrow, is located about 320 miles north of the Arctic Circle, on the coast of the Arctic Ocean. It is home to about 4,900 people, mostly Iñupiat, an indigenous Inuit ethnic group. The city changed its name to Utqiaġvik in 2016, which means “the place where we hunt snowy owls” in the Iñupiaq language.
The residents of Utqiaġvik are used to living in extreme conditions, with temperatures ranging from -56°F to 78°F and an average annual snowfall of 50 inches. They also have to cope with the long periods of darkness and light, which affect their circadian rhythms, mood, and health.
However, the polar night is not completely dark. There are different types of twilight, depending on how far the sun is below the horizon. The civil twilight, when the sun is less than 6 degrees below the horizon, lasts for about three weeks after the sunset and before the sunrise, creating a faint glow in the sky. The nautical twilight, when the sun is between 6 and 12 degrees below the horizon, lasts for about two months, producing a darker blue hue. The astronomical twilight, when the sun between 12 and 18 degrees below the horizon, lasts for about two and half months, making the sky almost black.
The polar night also offers a chance to witness some spectacular natural phenomena, such as the northern lights, the moon, the stars, and the polar stratospheric clouds. The northern lights, or aurora borealis, are caused by the interaction of charged particles from the sun with the Earth’s magnetic field, creating colorful curtains of light in the sky. The moon, which follows a 29.5-day cycle, can provide some illumination during the night. The stars, which are visible throughout the year, can be seen more clearly during the polar night. The polar stratospheric clouds, also known as nacreous clouds, are rare clouds that form in the lower stratosphere, about 12 miles above the ground, when the temperature drops below -108°F. They reflect the sunlight from below the horizon, creating a rainbow-like effect.
The sun will rise again in Utqiaġvik on January 23, 2024, at 1:16 p.m. local time, ending the 65-day polar night.
The city will then gradually gain more daylight until the summer solstice, when it will enter the polar day, lasting from May 10 to August 27.
The KTruth