- It is a portable cosmos, a gear computer that calculates where the sun, moon and planets are at a certain time, says Jonathan Lindström who is an archaeologist.

Large as a shoe box

It is called the Antikythera mechanism and has once been as big as a shoe box and the assessment is that it was manufactured around 100 BC. 

When it was found on the seabed more than a hundred years ago, it was in the form of a larger bronze plate and about eighty smaller pieces.

In the 2000s, the bronze fragments were x-rayed with modern technology and then you got a better idea of ​​how all large and small gears, shafts, bolts and plates were put together.

Solar eclipses

Then it was also easier to read the engraved pieces of text that describe how to read the positions of the then five known planets and the sun and moon on the front of the cosmological clock.

On the back of the watch were hands pointing out upcoming solar and lunar eclipses as well as upcoming sporting events.

Puzzle in three dimensions

But many parts are missing and for the researchers it was like putting together a puzzle in three dimensions to try to make the mechanism work.

The orbits of seven celestial bodies shall be coordinated and the device shall show how they are in relation to each other in the sky at a certain date.

Such a machine could be as large and complicated as anything, but the watch is no bigger than a shoe box.

The researchers understood that the gears must be used as smartly as possible and divided between several celestial bodies.

But the question was for a long time how.

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The cosmological watch with front and back and interior with all gears.

Photo: Tony Freeth

Ingenious solution

Now the Antikythera Research Team at London global university has made a crucial discovery that made the puzzle possible to complete.

They found that the designers of that time had a greater mathematical knowledge of the orbits of the two planets Venus and Saturn than had previously been known.

- The Greeks were brilliant.

It takes a lot of mathematical work to get the planets to share all the gears, says Jonathan Lindström.

This led to the researchers being able to put together the whole mechanism.

They publish the results in Scientific Reports.

- We know the cosmology of the Greeks from this time - but it has always been assumed that it was not put into practice, that they were not engineers.

But this shows that there was advanced engineering then as well, says Jonathan Lindström.