Midnight, but the day is still here
Imagine finishing dinner in northern Norway, taking a long walk and checking your watch. It is almost midnight. The Sun is still above the horizon. You have not accidentally slept through an entire day.
During part of the summer, places north of the Arctic Circle experience the midnight sun: Earth keeps turning, but the Sun does not dip below the horizon. The clue is the angle at which our planet spins.
A spin that never carries you into darkness
Earth’s axis is tilted by about 23 degrees. As the planet travels around the Sun, that tilt gives each hemisphere its turn leaning towards the sunlight. NASA’s explanation of the seasons connects this tilt with the changing length of our days.
In the far north during summer, the daily rotation can carry a place around in a circle that stays entirely on the sunlit side of Earth. The planet completes its turn; that place simply never crosses into the dark half.
Think of a tiny mark near the top of a tilted globe. With a lamp shining towards that end, turn the globe slowly. The mark can travel all the way round without losing the light. That is the useful picture behind the midnight sun.
Head farther north and the day gets longer
The effect lasts longer as you move towards the pole. Visit Norway’s guide gives Tromsø a midnight-sun season from about 20 May to 22 July. Farther north, Svalbard’s stretches roughly from 20 April to 22 August.
Those dates describe a summer phenomenon. Norway does not have midnight sunshine all year, and its southern cities do not share the far north’s round-the-clock Sun.
There is an opposite chapter too. When the northern hemisphere leans away from the Sun, places far enough north spend part of winter without a sunrise. The same tilt can produce both extremes.
A bright night can still be chilly
Before packing for a midnight walk, check the weather tomorrow as well as the daylight hours. The Sun being above the horizon does not guarantee a clear sky or a warm evening.
Temperature and daylight tell you different things. And the forecast’s “feels like” temperature also takes factors such as wind and humidity into account, as the Met Office explains. A bright sky is not a substitute for a jacket.
Perhaps that is what makes the midnight sun so strange: the clock says one thing, the light suggests another, and both are right. If that tilted globe has you curious, take a closer look at what causes the seasons.