A solstice is a day the Sun reaches the farthest point it ever gets from the equator — 23.4° north around June 21, 23.4° south around December 21. For the hemisphere leaning in it is the longest day of the year; for the other, the shortest. The word means “the Sun stands still”: its slow drift north or south stops and turns around.

Solstice

What is a solstice?

A solstice is a day the Sun reaches the farthest point it ever gets from the equator. Around June 21 it stands straight over the Tropic of Cancer, 23.4° north — the longest day of the year in the northern hemisphere and the shortest in the southern. Around December 21 it stands over the Tropic of Capricorn and the hemispheres swap. The word is Latin — sol, the Sun, and sistere, to stand still — because the Sun’s drift north or south stops on this day and reverses. That farthest-ever figure, 23.4°, is Earth’s tilt, and that is no coincidence: a solstice is the tilt, seen from the ground.

The June solstice from the side: sunlight meets Earth 23.4° north of the equator — as far north as the overhead Sun ever gets. Six months later the picture flips south.

Longest day, not earliest sunrise

The June solstice has the most daylight in the north, but the earliest sunrise lands about a week before it and the latest sunset about a week after. The two ends of the day do not move in step, because clock noon and Sun noon drift apart through the year — the equation of time. The whole pattern is sitting in the 7-day table on your own town’s sun page if you look at the week around the solstice.

What actually stands still

Watch where the Sun rises for a few weeks and it slides along the horizon, a little further north each morning through northern spring. At the solstice the slide stops, holds for a few days, and heads back the other way. That is the standing-still the name records — not the Sun pausing in the sky, but the turning point of its year.

At the polar circles it is all or nothing

On the June solstice the Sun does not set anywhere inside the Arctic Circle, and does not rise anywhere inside the Antarctic Circle. The polar circles sit at 90° minus 23.4 — the tilt’s other signature. Jump to a solstice on the day/night map and you can see it: the top of the map entirely lit, or entirely dark.

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Why the hottest weeks come later

The most sunlight is not the most heat. Land and ocean keep warming for as long as each day still delivers more energy than its night sheds, so the temperature peak lags the light peak by several weeks — July and August in the north, January and February in the south. The sea lags hardest of all, which is why beach water is warmest long after the longest day has gone.

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On the hub: Sunrise & sunset

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