The Sun at Night
Because the Earth's axis tilts, the area nearest poles stays constantly in sunlight during each hemisphere's mid-summer.   This land of the midnight sun, which includes parts of Alaska, Scandinavia, and the Soviet Union, in the northern hemisphere swings on the circle as the Earth turns on its axis.  But the circle is so small, that the places never rotate out of the Sun's light.  The Sun appears to sink towards the Earth's horizon, but stays visible all night.  In the northern hemisphere, this takes place in June.  In Antarctica, the sun shines all night during the southern summer late in December.