Top Ten Greek Astronomers

Alongside democracy and running around in circles and calling it athletics, Greek astronomy is one of the major legacies of the ancient world and was hugely important in the development of later Eastern and European astronomy. The stars and the galaxy are referenced by Homer and Hesiod but Iris Online has concentrated on the big boys (Sadly, they were all boys) of Classical and Hellenistic astronomy. They got a lot wrong but they got some things right and changed the way the ancients saw the world and beyond.

So here is our totally authoritative and totally subjective Top Ten Countdown....

 10. In at number ten is 5th Century Meton of Athens. We have mainly put him here because he makes a cameo appearance in Aristophanes’ Birds, but he also discovered what became known as the Metonic cycle, the common multiple of the solar year and the synodic (lunar) month,  so he must have had some idea what he was doing. He had an observatory just by the Pnyx and Ptolemy records that the Athenians had a table which recorded his observations as well as a description of the Metonic cycle. Impressive, huh?

 9. You have to be either stupid or very clever to have Socrates as one of your pupils. We have assumed Anaxagoras was the latter so put him in at number 9. He is actually the first philosopher of whom we have any clear record. He may not have been right to say that the sun was a blazing mass of metal but he was closer when he said that it was bigger than the Peloponnese, i.e. very big. He also suggested that the moon was a planet much like our with inhabitants. All this was too much for the the Athenians who banished him blaming him for Star Trek and other bad sci-fi.

8. Apollonius of Perga (born c. 262 BCE) became known for his work on conic sections. Archimedes, Menaechmus and Euclid also wrote about them but as their work is lost, it is good old Appollonius who gets the credit. As such, he was a major influence on later scholars such as Kepler, Newton and Descartes. For us that justifies his ranking here. For the ignorant (like me) a conic is a curve obtained at the intersection with a plane... Just look it up on Wikipedia.

7. Eudoxus of Cnidus was so poor that he walked seven miles and back each day  to attend Plato's lectures, and his friends had to raise funds in order that he could study astronomy in Heliopolis in Egypt. Presumably they paid for his ticket there as well. His main contribution to astronomy was to look at eclipses of the sun, planetary movement around the earth and the introduction of an astronomical globe. We know a lot of his work from Aristotle. Later astronomers added to his planetary system and found flaws in it. But for sheer effort, persistence and being a first, we give him a well-deserved pat on the back.  

6. Better know for his political philosophy Plato (428-348 BCE) also dabbled in astronomy. Then again, who didn't? The Greeks were nothing if not eclectic. Rather typically for him he believed that the earth, the sun and the planets were constructed with geometric elegance and simplicity and they moved in simple circles around the earth in endlessly repeated motions, some more complicated than others. Having stated this, Plato then challenged others to prove it... which now I come to think of it, seems a bit off.  Oh, to be a philosopher-king!

5. Claudius Ptolemy (c. AD 90 - 168) was a later Graeco-Egyptian astronomer whose treatise Almagest is the best surviving work from the ancient world and thus he was a important influence on later European and Islamic thinkers. His work tabled the planetary positions - present, past and future - and also catalogued a list of constellations and over one thousand fixed stars. His writings built extensively on earlier astronomers like Hipparchus but he remained a model for thinking for 1,500 years...

4. OK. This is impressive. Eratosthenes of Cyrene (born in 276 BCE) was the first to calculate the circumference of the earth, the first to calculate the tilt of the Earth's axis, he calculated the distance of the Earth from the Sun and calculated that actually the Sun was 27 times bigger than the Earth. Actually it is 109 times but since he did most of this without leaving Egypt and gave every fourth year an extra day, we forgive him. 

3. Aristarchus of Samos: what a guy. Living in the 3rd Century BCE, he was the first man who postulated that the sun was centre of the universe with the Earth revolving around it. On a winning streak he also suspected that the stars were not the gods’ daisy chains but in fact were like the sun but very, very far away. He also calculated in his best known work, On The Sizes and Distances of the Earth and the Moon, the distance of the sun from the moon. OK, he was a bit out - well, a lot out - but we applaud the effort.

2. Thales of Miletus (c 624 - 546 BCE) was one of the 'Seven Sages of Greece' and has been described as the first philosopher in the Greek tradition. His most famous proposition (as reported by Aristotle) was that water was the basis for all matter, based on his observation of moisture turning into air. He was also known for geometry ("Space is the greatest thing, as it contains all things."). His thinking which also concerned the nature of divinity set in motion the enquiring Greek tradition from which all astronomy evolves. Well done!

1. Born in Bithynia around 190 BCE Hipparchus of Nicaea has the honour of being awarded our number one spot. He was a Hellenistic mathematician and astronomer who constructed accurate models of the motions of the moon and the sun. As a trigonometrist he also developed a reliable method for predicting solar eclipses, a catalogue of the stars and he invented the astrolabe (star taker), whose uses include predicting the positions of planets and the stars. However his greatest achievement is to be given top place in this list.

Next month we will be compiling Top Ten Ancient Inventions. Please email suggestions to This email address is being protected from spambots. You need JavaScript enabled to view it.