File:Tromsø, northern Norway.jpg

English: Tromsø is a city located on the banks of the Tromsøfjord, (county of Troms and Finnmark in Norway), about 350 km north of the Arctic Circle (66 ° 33 '39 " of latitude). Because of its geographical location, the city is considered to be the gateway to the North Pole. In Tromsø, between 21 May and 23 July, one can experience the “midnight sun” during which the sun never drops below the horizon and, consequently, the night never falls. This only occurs in the northern hemisphere, in areas above the Arctic Circle. From 23 November to 18 January inclusive, the opposite happens - the sun does not rise above the horizon. The latter period is particularly favorable for observing the Aurora or Northern Lights. This image, acquired by one of the Copernicus Sentinel-2 satellites on 22 May, shows part of the county of Troms and Finnmark still completely covered by snow. The joint use of the Copernicus Sentinel-1 and Sentinel-2 satellites allows monitoring the ice thickness and the surface velocity of glaciers in the mainland of Norway and around the world. This data allows scientists to improve the predictions of sea-level variations on a global scale.