Six months
Explanation
The duration of daylight at any specific location on Earth is primarily determined by the Earth's revolution around the Sun and the permanent inclination of the Earth's axis at an angle of 66.5° to the plane of its orbit (or 23.5° from the vertical).
Analysis
The phenomenon of continuous daylight at the poles is a direct result of the Earth's axial tilt relative to the Sun:
- Vernal Equinox to Autumnal Equinox: From approximately March 21 to September 23, the Northern Hemisphere is tilted towards the Sun. During this entire period, the North Pole remains constantly exposed to sunlight, as the Sun never dips below the horizon. This results in approximately six months of continuous daylight.
- Autumnal Equinox to Vernal Equinox: Conversely, from approximately September 23 to March 21, the Northern Hemisphere is tilted away from the Sun. During this period, the North Pole remains in the Earth's shadow, experiencing approximately six months of continuous darkness.
- The South Pole experiences the exact opposite cycle.
Key Takeaway: Due to the Earth's axial tilt of 23.5°, the North Pole and South Pole experience alternating cycles of approximately six months of continuous daylight and six months of continuous darkness.