The North Pole is the northernmost point on Earth, where the Earth’s axis of rotation meets its surface. It is also the place where the Sun never sets in summer and never rises in winter. This phenomenon is known as the polar day and the polar night, respectively. But how does this happen, and what are the effects of living in perpetual darkness for months?
The Earth’s Tilt and the Seasons
The main reason why the North Pole experiences perpetual night in winter is because of the Earth’s tilt. The Earth is tilted at an angle of about 23.5 degrees from the vertical, relative to its orbit around the Sun. This means that different parts of the Earth receive different amounts of sunlight throughout the year, creating the seasons.
According to Global Clue, during the winter solstice, which occurs around December 21, the North Pole is tilted away from the Sun, and the Sun is below the horizon for the entire day. This marks the start of the polar night, which lasts until the spring equinox, around March 20, when the Sun rises above the horizon for the first time in months. During the summer solstice, which occurs around June 21, the North Pole is tilted towards the Sun, and the Sun is above the horizon for the entire day. This marks the start of the polar day, which lasts until the autumn equinox, around September 22, when the Sun sets below the horizon for the first time in months.
The Twilight Zone and the Midnight Sun
The polar night and the polar day are not absolute, however. There are periods of time before and after the solstices and the equinoxes when the Sun is not completely below or above the horizon, but rather close to it. This creates a twilight zone, where the sky is not completely dark or bright, but rather has a faint glow. According to PMEL NOAA, the twilight zone lasts for about six weeks before and after the winter solstice, and for about six weeks before and after the summer solstice.
The opposite of the twilight zone is the midnight sun, which occurs when the Sun is visible at midnight at the North Pole. This happens during the polar day, when the Sun is above the horizon for 24 hours. The midnight sun lasts for about 76 days, from late May to late July, according to PMEL NOAA.
The Effects of Perpetual Night on Life
Living in perpetual night for months can have significant effects on the physical and mental health of humans and animals. According to [BBC], some of the effects include:
- Disruption of the circadian rhythm, which is the natural cycle of sleeping and waking that is regulated by the exposure to light and dark. This can lead to insomnia, fatigue, depression, anxiety, and mood swings.
- Reduced production of vitamin D, which is essential for the absorption of calcium and the maintenance of bone health. This can lead to osteoporosis, rickets, and increased risk of fractures.
- Increased risk of seasonal affective disorder (SAD), which is a type of depression that occurs during the winter months. This can cause low mood, loss of interest, irritability, and weight gain.
- Changes in the behavior and physiology of animals, such as hibernation, migration, reproduction, and feeding. Some animals, such as polar bears, seals, and walruses, adapt to the polar night by relying on their senses of smell, hearing, and touch. Others, such as reindeer, foxes, and lemmings, change their fur color to blend in with the snow.
The Beauty of the Polar Night
Despite the challenges of living in perpetual night, the polar night also offers some unique and stunning sights that can only be seen at the North Pole. Some of these include:
- The aurora borealis, or the northern lights, which are colorful displays of light in the sky caused by the interaction of charged particles from the Sun with the Earth’s magnetic field. The aurora borealis can be seen throughout the year, but are more visible during the polar night, when the sky is darker.
- The stars, planets, and constellations, which are more visible during the polar night, when there is less light pollution. Some of the prominent celestial objects that can be seen at the North Pole include the North Star, the Big Dipper, and the Little Dipper.
- The moon, which can appear larger and brighter at the North Pole, due to the optical illusion known as the moon illusion. The moon can also create a moonbow, which is a rainbow-like phenomenon caused by the reflection and refraction of moonlight by water droplets in the air.
The polar night is a fascinating and extreme phenomenon that occurs at the North Pole in winter. It is a result of the Earth’s tilt and the seasons, and it creates a twilight zone and a midnight sun. It also affects the life and health of humans and animals, and it offers some beautiful and rare sights. The polar night is a challenge, but also a wonder, that can only be experienced at the top of the world.