Alaska spans an immense area covering a wide range of latitudes. Due to this vast geographic span, a simple “yes” or “no” answer to whether the sun sets is insufficient. The state’s position subjects its different regions to a dramatic spectrum of daylight and darkness throughout the year. Understanding solar activity in Alaska requires knowing both the specific location and the time of year, as the experience in northern towns differs greatly from southern cities.
The Role of Latitude and the Arctic Circle
The variations in Alaska’s daylight hours depend on the Earth’s axis, which is tilted at approximately 23.5 degrees relative to its orbit. This axial tilt is the reason for the planet’s seasons and the varying lengths of day and night. During the summer solstice, the Northern Hemisphere is tilted toward the sun, resulting in longer days. Conversely, during the winter solstice, the hemisphere is tilted away, leading to shorter days.
The Arctic Circle, an imaginary line of latitude at about 66.5 degrees North, represents the geographic boundary where these solar effects become most pronounced. Any location situated north of this line will experience at least one full day where the sun does not set and at least one full day where the sun does not rise. The closer a location is to the North Pole, the longer these periods of continuous light or darkness last. This astronomical definition explains why different Alaskan regions have radically different experiences of sunrise and sunset.
The Midnight Sun Phenomenon
The Midnight Sun is the result of a location’s latitude placing it in continuous sunlight around the summer solstice. This phenomenon occurs in all areas of Alaska situated above the Arctic Circle, such as Utqiagvik, the northernmost settlement in the United States. In Utqiagvik, the sun sets for the last time in mid-May and does not reappear until early August, creating a period of roughly 84 continuous days without a sunset.
During this time, the sun does not dip below the horizon, instead appearing to circle the sky in a low, gentle arc. The brightest period occurs when the sun reaches its highest point near noon, with the softest light happening near midnight when it is at its lowest point. This continuous daylight is also known as polar day.
The Polar Night Phenomenon
The opposite extreme is the Polar Night, which occurs during the winter months when the Northern Hemisphere is tilted away from the sun. For communities above the Arctic Circle, the sun remains below the horizon for 24 continuous hours or more. For example, in Utqiagvik, the sun sets in mid-November and does not officially rise again until late January, resulting in approximately 64 to 67 days without a true sunrise.
Despite the term “Polar Night,” this period is not characterized by absolute blackness. Instead, the middle part of the day often experiences “civil twilight,” where the sun is only a few degrees below the horizon. This allows for a few hours of soft, diffused light, often described as a pale blue glow, which illuminates the landscape. True darkness, or astronomical night, only occurs when the sun is far enough below the horizon that no light is scattered.
Variation Across Alaskan Regions
For the majority of Alaskans living in the southern regions, the sun always sets, but daylight hours are still dramatically affected by latitude. Cities like Anchorage and Juneau are located south of the Arctic Circle and therefore have a regular cycle of sunrise and sunset every day. However, their high latitude means the seasonal variation in daylight is far greater than in the lower 48 states.
In Anchorage, the summer solstice brings nearly 19 to 22 hours of functional daylight, with sunset occurring close to midnight. Even after the sun officially sets, the low angle of the twilight keeps the sky bright for hours. Conversely, the winter solstice leaves Anchorage with only about five and a half hours of daylight. This experience contrasts sharply with the Arctic, showing that while the sun always sets in the south, the rhythm of day and night is exaggerated compared to lower latitudes.