Midnight sun is the sun being above horizon throughout the night.

The Earth's axis is tilted by 23 degrees in relation to the ecliptic (the plane of its orbit around the Sun) and this causes the seasons. When your part of Earth is tilted toward the Sun, you get summer; when it is tilted away, winter. For any latitude, the angle between vertical and the noon sun ranges from latitude-tilt at the summer solstice to latitude+tilt at the winter solstice, and is exactly the latitude on the equinoxes.

In the tropics — within 23 degrees of the equator — that range includes 0° so at times the Sun is directly overhead. In Arctic or Antarctic regions — within 23 degrees of the poles — it includes 90° so at times the Sun is on or below the horizon even at noon or is above the horizon even at midnight.

To see the midnight sun, you need to be north of the Arctic Circle or south of the Antarctic circle (above 90-23=67° latitude) at a time close to the summer solstice, June 21 in the northern hemisphere or December 21 in the southern.

If you visit the same area in the winter you will experience the polar night, which means that the sun doesn't rise above the horizon. This offers a good opportunity to see the Aurora borealis, as the sky will be dark more or less around the clock.

Obviously you won't see the sun on a cloudy night, so it is a good idea to check the weather forecast before leaving.

Even in midsummer, it can be cold at high latitudes; see cold weather for advice on coping.

Some of the most interesting photos of the midnight sun use time lapse techniques to get multiple images of the sun as it drops toward the horizon then reverses direction and begins climbing back into the sky. These require a tripod and a moderately wide-angle lens. The timing can be done manually, but it is much easier if the camera can be set to do it for you.

See travel photography for more general discussion.

Muslims may have a problem if they are at high latitudes during the fasting month of Ramadan; the basic rule is that Muslims do not eat or drink while the sun is in the sky during that month; that would be fatal if followed rigorously in summer at high latitude. Various groups of Muslim clerics allow various modified rules: use Mecca time, use the time for the nearest Muslim country or your home country, fast for a fixed number of hours each day, or fast in a different month since in spring or fall the days are around 12 hours even at extreme latitude. However, some clerics insist that there can be no exceptions.

Muslim travellers should plan ahead for this, and consult their religious leaders, if it is likely to be a problem.

By definition, the midnight sun can be seen in two areas:

• Arctic
  • Alaska, United States
  • Canada
  • Greenland
  • Iceland
  • Norway including Svalbard
  • Sweden
  • Finland
  • Russia
• Antarctica

With the sun shining all night long, it is often difficult to sleep properly. It might be a good idea to check with your hotel if they are proper thick curtains in the rooms. Be sure to bring a sleep mask.