Polar night facts for kids

This picture shows the special blue twilight during the polar night in Longyearbyen, Svalbard, Norway. It's very far north, at 78° latitude!

Even at the South Pole in Antarctica, it gets dark during the polar night.

This is what noon looks like during the polar night in Naryan-Mar, Russia, on December 23, 2014.

The polar night is a cool natural event that happens near the very top and bottom of our planet. It's when the night lasts for more than 24 hours! This only happens in areas inside the polar circles.

The opposite of polar night is called the midnight sun, or polar day. That's when the Sun stays above the horizon for more than 24 hours. When we talk about "night," we mean the middle of the Sun is below the horizon.

Because Earth's atmosphere bends the Sun's rays (this is called refraction), the polar day actually lasts longer than the polar night. Also, the area that experiences polar night is a bit smaller than the area that gets the midnight sun. The polar circle is located at about 66.5 degrees latitude.

For example, in Kiruna, the northernmost city in Sweden (at 67°51'N), the polar night lasts for about 28 days. But the midnight sun lasts for about 50 days! When it's daytime in the Arctic Circle (north), it's nighttime in the Antarctic Circle (south), and vice versa.

Other planets or moons can also have polar nights if they tilt enough and spin much faster than they orbit their star.

What is the Polar Night Like?

Even though it's called polar night, it's not completely dark everywhere inside the polar circle. It's only truly dark in places very close to the poles (within about 5.5 degrees) and only when the Moon is not visible.

Areas closer to the edges of the polar circles experience a long twilight instead of total darkness. In fact, polar regions often have more twilight throughout the year than places near the equator.

The longest time the Sun is completely below the horizon varies a lot. It can be zero days just outside the Arctic Circle and Antarctic Circle. But at the actual Poles, the Sun can be below the horizon for up to 179 days!

However, not all this time is considered polar night because you can still see some sunlight due to refraction. The total time when any part of the Sun is above the horizon at the poles is about 186 days. These numbers are averages. Because Earth's orbit around the Sun is not a perfect circle (it's an ellipse), the South Pole actually gets about a week more of the Sun being below the horizon than the North Pole.

Different Kinds of Polar Night

This is what early afternoon looks like during the polar night in Tromsø, Norway.

The polar night on Nordkinn Peninsula in Norway. This is the northernmost peninsula in mainland Europe.

Just like there are different kinds of twilight (like civil twilight, nautical twilight, and astronomical twilight), there are also different kinds of polar night. Each type of polar night is defined by how dark it is, based on how far below the horizon the Sun is.

For example:

• Civil Polar Night: This is when the Sun is more than 6 degrees below the horizon. During this time, it's too dark to do outdoor activities without artificial light.
• Nautical Polar Night: This happens when the Sun is more than 12 degrees below the horizon. At this point, the horizon is no longer visible, and it's very dark.
• Astronomical Polar Night: This is the darkest type, when the Sun is more than 18 degrees below the horizon. The sky is completely dark, and you can see even the faintest stars.

So, even during the polar night, the amount of light can change depending on how far below the horizon the Sun is.

Images for kids

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  Ruka, Finland at noon in December

See also

In Spanish: Noche polar para niños