What is the phenomenon called when the sun does not set above the Arctic Circle on the summer solstice? Midnight sun.
The midnight sun occurs when Earth’s axial tilt keeps the Sun above the horizon for at least 24 hours. At the Arctic Circle, this can occur around the June solstice; farther north, the period lasts longer. At the North Pole, the Sun remains above the horizon for roughly six months, from around the March equinox to around the September equinox.
The Arctic Circle lies at approximately 66°34′ north, though its exact latitude changes gradually as Earth’s axial tilt varies. Atmospheric refraction and the fact that the Sun is a disk mean that visible sunlight can occur slightly beyond the ideal geometric boundary.
Midnight sun is not the same as twilight. Twilight is indirect light after sunset or before sunrise, while the midnight sun means the Sun itself remains visible. Aurora is a glowing atmospheric display caused by charged particles, and polar night is the opposite seasonal phenomenon, when the Sun stays below the horizon.