I + 14 : Hipparchus - Father of the Antikythira Device ?

On the horizon to the west, in the hazy afternoon, the small island of Antikythira comes into view. We are on the way to Kythira but will stay overnight in Antikythira. The island's name is familiar to many from the Antikythira Mechanism, the first computer of the world. It was found in 1901 half a mile east of where we will anchor. The device has 37 bronze gears which calculate the movements of the sun, moon and planets. It predicts solar and lunar eclipses.

Replica of the Antikythira Mechanism which was found in a wooden Box

The mechanism was made sometimes between 150 - 100 BC. Based on recent analysis researchers concluded that the device was calibrated with positional data from 178 BC. Vases found on the Roman shipwreck indicate that it came from Rhodes. The device is an extraordinary example of fine mechanics – something people thought the Greek were not yet capable of. A more detailed analysis of the wheels indicates that the device used the Corinthian calendar and Hipparchus’ calculation for the movement of the moon. Hipparchus was a famous Greek mathematician and the founder of modern astronomy.

Antikythira's Cape Glyphadia where the Mechanism was found in 45 meters Depth

In order to build the device though, the mechanics needed data, tables and ratios for the gears. Who compiled this work? We do not know but have some clues. Hipparchus directly or indirectly contributed. I call him the father of the Antikythera mechanism. Without his ground observations and mathematics, our first computer would not exist.

Hipparchus used a thin tube called Dioptra to measure Star Positions for his Catalog

Hipparchus was representative for the wonders of the Hellenistic Age when ancient know-how from the Hindus Valley, Mesopotamia and Egypt merged. Alexander the Great had united these culture; their knowhow became accessible to Greek philosophers and scientists who wondered about everything.

The Empires ruled by Alexander's Successors formed one big Hellenistic Cultural Sphere

Alexander's successors, the Seleucids, Ptolemy and Macedonians continued with this tradition. Alexandria, Pergamon, Rhodes and many other towns became centers of learning. Scrolls were written, copied and exchanged. Ideas – old and new – were discussed and developed. Knowledge was power. All these Hellenistic rulers had their own libraries. Alexandria and Pergamon were only the biggest.

Hipparchus from Nicaea (190 - 120 BC)

Hipparchus was born in Nicaea (Izmit today) but spent most of his life in Rhodes. We know that he also spent time in Alexandria. In both places, he had access to centuries old time series of astronomical data from Babylon. He based his work on this treasure trove of data and developed astronomy further. Using the Babylonian’s 360-degree system he developed the global grid we still use today - nicely parcelled in 30-degrees boxes. In this catalog he mapped 850 stars – the first accurate map of our sky.

Hipparchus working in Alexandria or Rhodes on the Roof with his Globe

What interested him most were the movements in the sky - the sun, moon and the planets. The Babylonian time series allowed him to track them. He discovered patterns which he investigated further with his own dioptra - a simple tube to record the positions observed. His most famous discovery was the precession, the gradual position changes of celestial bodies caused by the slight wobbling of the earth axis. Finally people understood why the solstice and equinox changed over time.

Hipparchus determined the distance to the moon by

using a lunar eclipse (partial in A = Alexandria and total

in H = Hellespont)

Hipparchus also calculated the precise length of the year (365 ¼ days), the distance of moon and sun, devised formulas to predict their precise position and thus knew about upcoming lunar and solar eclipses. At a time when everybody was superstitious such knowledge was priceless. Priests and rulers used it to legitimise their claim on divinity. With Hipparchus' ratios, the mechanics from Rhodes could also build a device to predict eclipses in the future. Finally they had what they needed to calibrate the gears.

A Page from the Log Book we used in Highschool

To make his calculations, Hipparchus developped mathematics further. He is the father of trigonometry as we know it and manually calculated thousands of sinus and co-sinus values. I remember these tables from Highschool. We went to school before the time of pocket calculators and used rulers and log books to do trigonometry. I was 16 years old when I saw the first HP-35 in the hands of my math teacher. We were amazed what this little machine could do.

Not many of Hipparchus’s texts survived. Luckily, much of his work was adopted and copied by Ptolemy. Hipparchus was a true pioneer. The scientific revival of the Renaissance would not have been possible without his contribution to science and math.

View on the Kapsali Bay from the Kythira Fortress. The

MYRA is the double Master in the Middle of the Bay

Am finishing this blog from the Bay of Kapsali where we arrived a few hours ago. Kythira is the only Aegean island the Ottoman were never able to capture from Venice. They sent their “famous” corsair Barbarossa instead. With raids he enslaved as much of the population as he could. Venice had to fortify the island to protect its inhabitants. We already climbed the Venetian Fortezza of Kythira and now enjoy the beauty of Kapsali Bay. Dinner on the boat.