AY Honors/Midnight Sun/Answer Key
1. Describe the geographic areas the midnight sun may be seen in.
The midnight sun is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the sun remains visible at the local midnight.
2. Describe why and at what time of the year the phenomenon may be seen.
Around the summer solstice (approximately June 21 in the north and December 22 in the south) the sun is visible for the full 24 hours, given fair weather. The number of days per year with potential midnight sun increases the farther towards either pole one goes. Although approximately defined by the polar circles, in practice the midnight sun can be seen as much as 90 km outside the polar circle, and the exact latitudes of the farthest reaches of midnight sun depend on topography and vary slightly year-to-year.
The phenomenon is caused by the Earth's axial tilt, which at the solstice tilts one pole away from the sun (polar night), and tilts the other towards the sun (the midnight sun). This is easily illustrated with a globe and a flashlight, by observing which parts of the globe are illuminated (or in shadow) as the globe rotates on its axis, and as the globe orbits around the "sun" (or in our case, the flashlight).