Greenland is the world’s largest island, where traditional concepts of day and night often cease to apply. The answer to whether the sun ever sets is not a simple yes or no, but rather a complex, seasonally dependent condition. Greenland’s immense size means that different regions experience vastly different solar cycles throughout the year.
Greenland’s Position Relative to the Arctic Circle
Understanding the sun’s behavior in Greenland begins with the Arctic Circle, located at approximately 66.5 degrees North latitude. This parallel defines where the most extreme solar conditions can occur. Roughly two-thirds of the entire landmass of Greenland lies to the north of this line, placing the majority of the country within the polar zone.
Regions situated south of the Arctic Circle, such as the capital city of Nuuk, which sits near 64 degrees North, experience a normal pattern of daily sunrises and sunsets. Although the summer days are exceptionally long and winter days are short, the sun still dips below the horizon every 24 hours in these southern settlements. Moving north of the Arctic Circle, however, is where the solar cycle changes completely, leading to periods when the sun either never sets or never rises.
The Summer Phenomenon of the Midnight Sun
In the summer months, for any location above the Arctic Circle, the sun remains continuously visible above the horizon, creating the phenomenon known as the Midnight Sun. This is a period of 24-hour daylight where the sun completes a full circle in the sky without fully descending. The duration of this continuous daylight is directly proportional to the distance a location is from the Arctic Circle.
Closer to the boundary, the Midnight Sun might only last for a few weeks around the Summer Solstice in June. However, towns further north, such as Ilulissat, experience the sun remaining aloft for over two months. In Qaanaaq, one of Greenland’s northernmost settlements, the sun does not set for approximately three and a half months, from late April until late August.
Even in the southernmost parts of Greenland, which do not experience the Midnight Sun, the effect of the sun’s high position is still felt. During the summer, these southern regions may have up to 20 hours of daylight between sunrise and sunset. The sun only briefly dips below the horizon, resulting in a prolonged twilight known as “bright nights” rather than true darkness.
The Winter Phenomenon of Polar Night
The opposite extreme occurs during the winter, when the sun does not rise above the horizon for days or even months, a period referred to as the Polar Night. This phenomenon also increases in duration the further north a location is situated. In northern settlements like Uummannaq and Qaanaaq, the sun disappears completely below the horizon for several weeks or months around the Winter Solstice.
Despite the name, the Polar Night is rarely a period of total, pitch-black darkness, especially in the populated coastal areas. In many northern communities, the sun is only slightly below the horizon, allowing for a few hours of mid-day illumination known as civil twilight. Civil twilight occurs when the sun is less than six degrees below the horizon, scattering enough light to create a noticeable, albeit dim, daylight.
For example, in Ilulissat, which sits well north of the Arctic Circle, the period when the sun does not rise lasts from late November to mid-January. During this time, the middle of the day is marked by a soft, ethereal blue light that provides enough visibility for some outdoor activities. The return of the sun, often in mid-January, is a celebrated event in these northern communities, marking the end of the darkest period of the year.
Earth’s Axial Tilt and the Cause of the Extremes
The ultimate cause of Greenland’s extreme daylight cycles is the stable axial tilt of the Earth relative to its orbital plane around the Sun. The Earth’s axis of rotation is tilted by approximately 23.5 degrees. This tilt is responsible for the seasons, as it changes which hemisphere is angled toward the sun over the course of the year.
This specific 23.5-degree angle determines the location of the Arctic Circle at 66.5 degrees North latitude (90° minus 23.5°). During the Northern Hemisphere’s summer, the Earth’s tilt causes the North Pole to be angled toward the sun. As the planet rotates, any location north of the 66.5-degree line remains continuously exposed to sunlight, as the sun never dips below the horizon.
Conversely, during the Northern Hemisphere’s winter, the North Pole is tilted away from the sun. This positioning causes the sun’s rays to fall short of the area above the 66.5-degree latitude line. Consequently, locations within the Arctic Circle remain in the Earth’s shadow as it rotates, resulting in the sunless days of the Polar Night.