The residents of Wiseman, Alaska; Murmansk, Russia; and Tromsø, Norway, might be having a hard time getting a good night’s sleep. That’s because there’s no night to sleep through. All three towns are above the Arctic Circle, so they’re seeing the midnight Sun — a time when the Sun never sets.

There’s constant daylight because of the time of year. Today marks the summer solstice in the northern hemisphere. It’s the start of the summer season, and the longest day of the year north of the equator.

The Sun is farthest north for the year, and that’s the key. At the solstice, the north pole dips most directly toward the Sun. The Sun shines in a wide circle around the pole. Anything above about 66 degrees north latitude — the Arctic Circle — sees constant daylight.

How long the Sun stays above the horizon varies by latitude. Close to the Arctic Circle, it’s a few days or weeks. For those farther north, it’s longer. For the northernmost town in Alaska, for example, it’s almost three months. For the northernmost town in the world, on a Norwegian island, it’s more than four months. And for the north pole itself, it’s six months from sunrise to sunset.

Of course, it’s just the opposite in the southern hemisphere. So the team that spends the winter at the south pole is just half way through the long night. In essence, that makes it midnight — with three more months until the south pole sees its own “midnight Sun.”
 

Script by Damond Benningfield

Support McDonald Observatory