Almost everyone on earth is accustomed to the inevitable cycle of day and night. We take it for granted that we've designed our lifestyle to be in rythm with the rising and setting of the sun. However it is not a surprise that there are people on our own earth who have much longer days and nights. They live in the land of the midnight sun, where the generous sun shines throughout the day for months together!
This intriguing phenomenon is observed in the regions northern to the Arctic circle and southern to the Antarctic circle. Hence the people who witness it are those few living in Norway, Finland, Sweden and Greenland. It is also seen in Northern parts of Canada, Alaska(U.S), Iceland and few uppermost parts of Russia. This midnight sun occurs during summer in these northern regions. Being an astronomical phenomenon caused by the Earth's orbit around the sun, it is a spectacular sight to watch the sun shine endlessly in the sky. Norway is popularly known as the land of the midnight sun, since a part of it enjoys the sun endlessly for a period of about four months in summer. The sun never sets for about 73 days in the Utsjoki district of Northern Finland. Another spectacular sight in this region is the appearance of Northern Lights or "Aurora Borealis". As one goes further approaching the poles, the effect of midnight sun augments. Finally at the poles, the sun rises and sets only once a year. Thus at the poles a day or night is equal to 6months in length. At the poles and nearby regions, these are referred to as the 'polar day' and 'polar night'. At the poles, the sun actually shines for 186 days. They stay dark for the rest of the year. Similarly, in the "lands of the midnight sun", there are periods during winter when the sun never shows up in sky, when people have to rely entirely on artificial lighting. Though amusing to others, some natives and visitors of these regions experience problems of sleep due to the anomalies in natural lighting.
As many of us know, the earth is slightly (23.5 degrees) tilted in its orbit around the sun. This exposes the poles to the sun for half a year each irrespective of day and night. The rest of the time keeps them completely hidden from sunshine, and thus causes the polar day and polar night. As regions lying so close to the north pole, the Arctic-crossing countries also experience this effect to some extent causing the midnight sun. In these regions, the sun sometimes appears to be high in the horizon though it is below, due to atmospheric refraction. Areas southern of the Arctic circle experience twilight due a similar effect, causing enough natural illumination in the sky during the nights. This is known as "White night" or "twilight sky". The phenomena of polar day / polar nights, midnight sun and similar effects can be better understood by knowing about the Earth's orbit around the sun. A best source to learn more about such planetary phenomena would be Astronomy Software. Ideally, a free astronomy software which can simulate time-forwarded demos of planetary motion would help. In general, anybody willing to learn in detail about the natural phenomena attributed to planetary motion would find Astronomy software to be greatly helpful.
Christian Nuesch is the creator of Asynx Planetarium, an easy-to-use, free astronomy program that helps render and create sky maps of the moon, planets, stars and constellations. It features time-traversal to simulate motion through past and future, graphics, animations and a location customization feature. You can download the free Asynx Planetarium Software at http://www.asynx-planetarium.com .