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Midnight sun

earth science Maturity 7-9 Next article →

The midnight sun, also called a polar day, is a natural phenomenon where the sun remains visible at local midnight. This event occurs during the summer months in specific regions of the world. These regions are located north of the Arctic Circle or south of the Antarctic Circle. At these high latitudes, the sun does not set below the horizon for extended periods. Instead, it appears to move in a circular path across the sky. In the Arctic, the sun appears to move from left to right. In the Antarctic, the apparent motion is from right to left.

Midnight sun
Midnight sun

This phenomenon is caused by the axial tilt of the Earth. The Earth does not sit straight up and down in its orbit. It has an axial tilt of approximately 23 degrees, 26 minutes, and 21 seconds. During the summer, this tilt causes one of the poles to lean toward the sun. As the Earth rotates on its axis, the sun stays above the horizon for certain locations. At the North Pole, the sun stays visible for about six months. This period lasts from approximately March 18 to September 24.

Midnight sun dates svatlas
Midnight sun dates svatlas

The duration of the midnight sun depends on how close a location is to the poles. At the Arctic Circle, the sun is only visible for one day during the summer solstice. However, as you move further north, the period of continuous sunlight increases. For example, at Cape Nordkinn in Norway, the midnight sun lasts from May 14 to July 29. In the Svalbard archipelago, it lasts from April 20 to August 22. At the extreme points of the North and South Poles, the sun stays visible for half the year.

Atmospheric refraction plays a significant role in when and where the sun is seen. Refraction is the bending of light as it passes through the atmosphere. Because of this effect, the sun may be visible even at latitudes slightly south of the Arctic Circle. It can also be seen up to one degree beyond the official circle depending on local conditions. This explains why most of Iceland experiences the midnight sun even though it is mostly south of the Arctic Circle. Refraction also makes the period of sunlight at the poles slightly longer than six months.

Optical effect march sunset - NOAA
Optical effect march sunset - NOAA

Many different countries and territories experience the midnight sun. In the Northern Hemisphere, these include Canada, Finland, Greenland, Iceland, Norway, Russia, Sweden, and the United States. Murmansk, Russia, is the largest city north of the Arctic Circle with a population of 270,000. It experiences the midnight sun for 62 days, from May 22 to July 22. In Finland, the sun does not set at all for 72 days at the country's northernmost point. Because there are no permanent human settlements in Antarctica except for research stations, the southern experience is limited to those specific areas.

Midnight sun dates svatlas
Midnight sun dates svatlas

Some regions experience a related phenomenon known as white nights. This occurs when the sun stays less than 6 or 7 degrees below the horizon. In these places, it does not get completely dark, allowing for activities like reading without artificial light. This happens during both the Northern and Southern Hemisphere summer solstices. Saint Petersburg, Russia, is famous for its white nights between June 11 and July 1. The city even celebrates this with a White Nights Festival.

Admiralty Embankment of Neva River in Saint Petersburg during the White nightsIMG 4236
Admiralty Embankment of Neva River in Saint Petersburg during the White nightsIMG 4236

In Fairbanks, Alaska, the twilight is significant enough that they hold a Midnight Sun Game baseball competition every June 21.

The timing of the sun's movement is also affected by the Earth's orbit. The periods of polar day and polar night are not equal in length. This is because the Earth is at perihelion, or closest to the sun, in early January. It is at aphelion, or farthest from the sun, in early July. In the Northern Hemisphere, the polar day is longer than the polar night. For instance, in Utqiagvik, Alaska, the polar day lasts 84 days while the polar night lasts 68 days. At the North Pole, the polar day lasts 186 days, while the polar night lasts 179 days.

Midnight sun dates svatlas
Midnight sun dates svatlas
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🖼️ Images & Media (7)
File:Midnight sun.jpg
Midnight sun.jpg
File:Полярный день над оз. Ожогино.jpg
Полярный день над оз. Ожогино.jpg
Polar Day's Night-HD.webm
File:Admiralty Embankment of Neva River in Saint Petersburg during the White nightsIMG 4236.JPG
Admiralty Embankment of Neva River in...
File:Norra Hamn Luleå.jpg
Norra Hamn Luleå.jpg
File:Midnight sun dates svatlas.png
Midnight sun dates svatlas.png
File:Optical effect march sunset - NOAA.jpg
Optical effect march sunset - NOAA.jpg
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