Exploring The World: Midnight Sun

Midnight sun is visible in areas north the northern and south the southern polar circle in the summer around midnight.

From a location directly at the polar circle out observed, the sun goes once per year - to the time of the summer sunning turn (more exact: the respective north or south summer sunning turn) - not under. After it achieved its deepest conditions over the horizon in the run of the day, it climbs again. The further one approaches now during the time around the summer sunning turn of the north polar circle from the north pole (and/or of the South Pole circle from the South Pole), to observe to the more days is the procedure of the midnight sun. Since the sun does not sink here under the horizon, one speaks of the polar day. The polar day would have to take directly at the geographical pole a half year. Due to the refraction of light (refraction) in the terrestrial atmosphere the polar day continues however somewhat longer than a half year.

The term midnight sun lets arise rapidly the mistake, the sun its deepest conditions around 24:00 clock would always achieve. This is due to different phenomena at a certain place only approach the case:

* On the one hand depends the time sun lowest point on the degree of longitude of the place, because a time belt defines the middle Sonnenzeit of a certain degree of longitude as the there valid time; this however for a whole range at degrees of longitude (e.g. 15 degrees of longitude). At the edge of a time belt the middle Sonnenzeit can over e.g. 30 minutes of that the time belt deviate (this deviation remains the year over constantly).

* On the other hand the true Sonnenzeit varies in the course of the yearly over about plus/minus one quarter of an hour also for a given place (phenomenon of the Zeitgleichung). Reason for the fact is among other things that the earth rotates because of their easily elliptical course around the sun with changing speed around the sun.

* In addition the true midnight shifts itself a further hour during a summer time regulation.

At the north cape the midnight sun achieves its deepest conditions on the average around 23:17 clock MEZ and/or 00:17 clock Central European Summer Time and is here from the 11. To observe May by 31 July, while one can observe the midnight sun on Svalbard from 20 April to 25 August.

The different daily and night length on all widths of our earth find its cause in the oh position of our earth to the ecliptic, to the earth orbit level. Our Erdachse stands for the level of its orbit not perpendicularly, but exhibits an angle of inclination of 23,44 degrees. If the Erdachse would stand perpendicularly to the earth orbit level, then the sun would move always exactly all year round at both Poland on the horizon along. This actually happens only for short time twice in the year: to the astronomical autumn and beginning of spring.