The longest day of the year in the northern hemisphere is usually said to be a single day in June (it varies from June 20 to June 23), but that only applies in the temperate zone (the area from the Tropic of Cancer to the Arctic Circle in the northern hemisphere). If you go north of the Arctic Circle, there will be at least one day when the sun doesn’t set, so the longest “day” (the time from sunrise to sunset) will be at least 48 hours. If you go all the way to the North Pole, the sun rises on the March equinox, and sets on the September equinox, so the longest (and only) day of the year is six months long. There will also be at least one day when the sun doesn’t rise, so the shortest “day” of the year, when the sun doesn’t rise at all, will also be from 48 hours to six months long.
Things are even weirder in the tropics. The longest day of the year is the day when the sun is closest to being directly overhead. On the equator, that’s actually two days every year – the equinoxes. There are also two shortest days of the year – the solstices. If you’re somewhere between the equator and the Tropic of Cancer, there will be two longest days – one when the sun is directly overhead and on it’s way farther north in the sky, and one when it’s overhead and on it’s way south, but there will only be one shortest day – the December solstice.
Similar rules apply to the southern hemisphere, but offset by six months.
Some thoughts on the longest day of the year:
The longest day of the year in the northern hemisphere is usually said to be a single day in June (it varies from June 20 to June 23), but that only applies in the temperate zone (the area from the Tropic of Cancer to the Arctic Circle in the northern hemisphere). If you go north of the Arctic Circle, there will be at least one day when the sun doesn’t set, so the longest “day” (the time from sunrise to sunset) will be at least 48 hours. If you go all the way to the North Pole, the sun rises on the March equinox, and sets on the September equinox, so the longest (and only) day of the year is six months long. There will also be at least one day when the sun doesn’t rise, so the shortest “day” of the year, when the sun doesn’t rise at all, will also be from 48 hours to six months long.
Things are even weirder in the tropics. The longest day of the year is the day when the sun is closest to being directly overhead. On the equator, that’s actually two days every year – the equinoxes. There are also two shortest days of the year – the solstices. If you’re somewhere between the equator and the Tropic of Cancer, there will be two longest days – one when the sun is directly overhead and on it’s way farther north in the sky, and one when it’s overhead and on it’s way south, but there will only be one shortest day – the December solstice.
Similar rules apply to the southern hemisphere, but offset by six months.