Why Clocks Run Clockwise
Look at any clock face. The hands go round from 12, over to 3, down to 6, across to 9 and back up to 12. It's so standard that we've named a direction after it. Clockwise.
But think about that for a second. A clock would tell the time perfectly well if its hands went the other way. Nothing about gears or springs demands one direction over the other. At some point, the direction had to be chosen.
So who chose it? The best answer we have points not to a clockmaker, but to the Sun.
The older clock
Long before anyone built a mechanical clock, people told the time with shadows.
The simplest version is a stick standing upright in the ground. As the Sun moves across the sky during the day, the stick's shadow swings round and changes length. Mark where the shadow falls at different times, and you have a sundial.
The part that casts the shadow is called the gnomon, which is simply the name for the pointer on a sundial. Sundials come in all sorts of designs, but they all rely on the same idea: the Sun moves in a regular way, so its shadow does too.
They're also very old. The earliest sundials known from the archaeological record are shadow clocks from around 1500 BC, from ancient Egypt and Babylonia. That's about 3,500 years of reading the time from the ground.
Why the shadow moves the way it does
Now for the key question. Which way does the shadow go round?
It depends where you're standing on Earth.
In the northern hemisphere, outside the tropics, the Sun rises in the east, climbs across the southern part of the sky, and sets in the west. At noon it's due south, so a stick's shadow at noon points north, away from the Sun.
Follow the shadow through a day. In the morning, with the Sun in the east, the shadow points west. At noon, it points north. In the evening, with the Sun in the west, it points east. So on the ground, the shadow sweeps from west, through north, round to east.
Stand behind the stick facing north, and that's left to right. Look down on a horizontal sundial from above, and the shadow is turning in exactly the direction we now call clockwise.
The handover
The first mechanical clocks didn't start appearing in Europe until around the start of the fourteenth century. By then, people in Europe had been reading the time from sundials for a very long time, and those sundials all turned the same way.
The widely held explanation is that clockmakers simply copied what people already knew. If you're used to time moving round a dial in one direction, a new clock that moved the other way would feel wrong. So the hands followed the shadow.
It's worth being clear about what that is. It's an inference, not a documented decision. No surviving record shows a medieval clockmaker sitting down and choosing a direction for that reason. One NASA educational page puts it carefully: it "has been claimed" that clockwise motion was chosen because of the sundial's shadow. Another writer on the subject admits there's no way to prove it, but says it makes sense. That's about where the evidence sits.
The sundial that runs backwards
Here's the twist that makes the story so satisfying.
Go south of the equator, to Sydney, say, or Cape Town, or Buenos Aires, and everything flips. Outside the tropics, the Sun now crosses the northern part of the sky. At noon it's due north, and a stick's shadow points south.
Follow that shadow through the day and it sweeps from west, through south, to east. Look down on a horizontal sundial there, and the hour marks run the other way round. Anticlockwise.
So a sundial in Sydney, Cape Town or Buenos Aires turns in the opposite direction to a clock on the wall right beside it. The clock isn't following the local sky at all. If the usual explanation is right, it's following a northern sky, because that's where mechanical clocks were developed. One magazine article on the subject points out that clock-making was almost exclusively a northern-hemisphere pursuit, and wonders whether clocks would run the other way if the south had got there first.
In other words, "clockwise" is most likely a northern habit that became a world standard.
Clocks that go the other way
If the direction is a habit rather than a law of physics, you'd expect a few exceptions. And there are.
In Florence's cathedral there's a clock by the painter Paolo Uccello that runs anticlockwise. On the Jewish Town Hall in Prague, there's a clock with Hebrew lettering that also runs anticlockwise. In 2014, the clock on Bolivia's national congress building in La Paz was set to turn anticlockwise too. And there have reportedly been novelty kitchen clocks that run backwards.
They all work perfectly well. You just have to read them the other way. They're rare, but they make the point: the direction was a choice, and the choice could have gone differently.
What the clock remembers
So the next time you glance at a clock face, it's worth a moment's thought. Those hands aren't just counting minutes. They're probably copying the path of a shadow across the ground, in the part of the world where people first built machines to keep time.
Every clock very likely carries a small fossil of where timekeeping grew up. And if you happen to live in the southern hemisphere, you can go outside on a sunny day, put a stick in the ground, and watch the original version run the other way.
Sources
NASA Goddard (D. Stern), "The Sundial", From Stargazers to Starships. https://pwg.gsfc.nasa.gov/stargaze/Sundial.htm (accessed 1 Nov 2026)
Wikipedia, "Sundial" (cross-check only). https://en.wikipedia.org/wiki/Sundial (accessed 1 Nov 2026)
Martin Fone, Country Life, "Curious Questions: Why do clocks go clockwise?" (25 April 2020). https://www.countrylife.co.uk/luxury/curious-questions-why-do-clocks-go-clockwise-213343 (accessed 1 Nov 2026)
