Ancient Greeks knew how to calculate the recurring patterns of lunar eclipses thanks to observations made for centuries by the Babylonians. The Antikythera mechanism would have done those calculations for them—or perhaps for the wealthy Romans who could afford to own it. The depiction here is based on a theoretical reconstruction by the author and his collaborators.
Image: Jean-Francois Podevin and Tony Freeth
In Brief
- The Antikythera mechanism is a unique mechanical calculator from second-century B.C. Greece. Its sophistication surprised archaeologists when it was discovered in 1901. But no one had anticipated its true power.
- Advanced imaging tools have finally enabled researchers to reconstruct how the device predicted lunar and solar eclipses and the motion of the moon in the sky.
- Inscriptions on the mechanism suggest that it might have been built in the Greek city of Syracuse (now in modern Sicily), perhaps in a tradition that originated with Archimedes.
More In This Article
If it had not been for two storms 2,000 years apart in the same area of the Mediterranean, the most important technological artifact from the ancient world could have been lost forever.
The first storm, in the middle of the 1st century B.C., sank a Roman merchant vessel laden with Greek treasures. The second storm, in A.D. 1900, drove a party of sponge divers to shelter off the tiny island of Antikythera, between Crete and the mainland of Greece. When the storm subsided, the divers tried their luck for sponges in the local waters and chanced on the wreck. Months later the divers returned, with backing from the Greek government. Over nine months they recovered a hoard of beautiful ancient Greek objects—rare bronzes, stunning glassware, amphorae, pottery and jewelry—in one of the first major underwater archaeological excavations in history.
This article was originally published with the title Decoding an Ancient Computer.
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18 Comments
Add CommentI have had the distinct pleasure of meeting with members of the Antikythera Mechanism Research Project while working on publicity for the kids' interactive exhibition "Gods, Myths and Mortals: Discover ancient Greece" currently open at CMOM (Children's Museum of Manhattan) located at 212 W. 83rd Street. There you can continue your quest to learn more about the Mechanism and view a replica reconstruction model based on latest research. The mystery of the Antikythera Mechanism device continues to fascinate the minds of young and old. Go see it!
Reply | Report Abuse | Link to thisIt is really amazing! It is a scientific- detective job well done that provides us with tremendous insight of the origins of scientific thinking and also makes us feel humble confronted with the accomplishments made by those men a hundred or so years before Christ. The models they had were to certain extent crude but at the same time reveal the existence of very bright minds and very persistent workers. Congratulations, what you have accomplished (by successfully studying this ancient mechanism) is of tremendous importance!
Reply | Report Abuse | Link to thiswwwwwWOW. From sheep herders to sophisticated specialists capable of something like this... Think of how many people lived and died in those towns, those cities, for centuries, and their lives, busy as our own, dedicated to their specialties, to free astronomers, mathematicians, metalworkers, artisans, to be capable of producing this amazing work of functional high art. I do wonder if this was the culmination of their technological ability of the time, or if there was more...
Reply | Report Abuse | Link to thisI only wonder why it has been found now and not in an earlier period of time by some other welbalanced observer or a fumbling little sheep boy out in the big city.It amazes me how some items found now adays havnt been found earlier.
Reply | Report Abuse | Link to thisIt was found by chance by Greek sponge divers on an ancient wreck about 150 feet under water in 1900/01. It was not at first recognized as anything important until it split apart some months after it was recovered from the sea floor. It has taken more than a hundred years of investigation to reach our current level of understanding of this extraordinary object.
Reply | Report Abuse | Link to thisVery interesting commentaries and our friend Eleni77 tells us about a replica that has been constructed. I was precisely thinking (and I would like to mention) that may be a modern version of the artifact can be constructed. It could be an actual device or software that come up with the same outcomes (but more precise) than the (what’s the name of that wonder?) Antikythera Mechanism. I have no idea if the device or software would sell to guarantee a return in investment. I am still trembling and exited about what I read. Many thanks to the people that took the trouble and invested time and effort in searching this matter. They should feel very satisfied and that’s the greatest reward; but how to translate this well deserved satisfaction into dollars? They will surely find a way.
Reply | Report Abuse | Link to thisIn the article Decoding an Ancient Computer from Scientific American (December 2009 Volume 301 Number 6, Pages 76-83), Tony Freeth discusses a recent archaeological finding that sheds light on how technologically advanced Ancient Greece really was. Modern archaeologists were astounded by how close the Greeks got to developing and using technology that wasnt discovered gain for another millennia and a half. This Greek mechanism was found in the early twentieth century and has had much mystery surrounding it ever since. This mechanism is called the Antikythera mechanism. It was speculated within a few years of discovery that this ancient mechanism was an astronomical calculator. This was partially correct, but it was recently found that this mechanism does much more than that, for example, it shows when the next Olympics should be. A few questions still remain, such as how it works, who created it and when it was created.
Reply | Report Abuse | Link to thisThis article was very interesting for a number of reasons. First, it shows how scientifically advanced a civilization could be in the ancient world; this mechanism took some of todays top archaeologists years to decipher its meaning and the basics to how it works. Also, in ancient history class we are currently talking about the Greeks, and one aspect that seems to have been left out in the history books is the extent of their scientific achievements. This article shows just one example of how technologically astute the Ancient Greeks were.
As the saying goes, you dont know what you dont know, there could still be many more ancient artifacts in the ocean waiting for modern archaeologists to uncover them that could be as amazing, or even surpass the Antikythera mechanism. This article is important because it gives us an appreciation of how ancient civilizations understood extra-terrestrial events, such as solar eclipses. By understanding how the Greeks and other sophisticated ancient civilizations developed and used technology, we can enhance the development of our own technology to accelerate the progression of mankind.
- BJM
Many thanks to Mr Freeth for an enticing article. My son Dr Ken Shamir and I were discussing this and asked who might have been interested in such an instrument. We came up with : Priests! They were the ones most interested in forecasting the heavens and agricultural calendrics: when to till, to sow, etc. Of all the priesthoods, the most sophisticated in the period were in Alexandria, Egypt. We ask if the device could have been built there, as opposed to Syracuse, Sicily, or Rhodes, Greece. After all the Greek Ptolemys ruled Egypt at the time. Perhaps a hint can be had by the positions of heavenly bodies as calculated for any given date. Are these positions correct for a given specific latitude? Would that be the latitude of the city wherein made, or used, or where the data was collected? Could the unknown gear have been a modifier to take into account either latitude or longitude or both?
Reply | Report Abuse | Link to thisThank you for any response.
Shamir raises a number of very interesting questions. We really don't know who it was made for. Various suggestions have been made, such as priests, astrologers, educators or a rich patron. We certainly cannot rule out a religious connection since the heavenly bodies were considered to be Gods and Goddesses. There is an on-going debate as to the origins of the instrument. For many decades, Rhodes was considered to be the most likely place of manufacture because much of the cargo of the Antikythera ship cam from the Eastern Mediterranen and becasue of the strong astronomical tradition in Rhodes - particularly with the great astronomer Hipparchos and his successor Posedonios (who is also known to have made a similar instrument from the writings of Cicero). Alexndria was always considered to be the next most likely location after Rhodes. The research on the month names of the 19-year Metonic calendar (as reported in Naure in July 2008) has strongly challenged all these ideas. The rare month names in the calendar are of Corinthian origin. This appears to confirm that the instrument was made for use in a Corinthian culture. The Corinthian colony of Sicily is just one possible place. It could have been made for a range of locations in northwestern Greece or even Corfu. There are some indications in the Mechanism that are latitude dependent - for example, the order of the star events in the parapegma (star calendar) that is inscribed on the front plate of the Mechanism. (This is the subject of a new academic publication in preparation.) So far, this has not given us strong enough evidence to make a definitive judgement about the latitude for which the Mechanism was intended. These are all fascinating questions and we hope that future research will begin to give us clearer answers. Many thanks for your email - Tony Freeth.
Reply | Report Abuse | Link to thisThank you Dr Freeth. Is there sufficient differential latitude around the Mediterranian to warrant the instrument requiring an alterable setpoint to take into account the sun's 28 year cycle? At least the Jewish calendric norms take this into account (as Dr Shamir reminded me, the current year is one of the sun's "birthyears"). We surmise that other priesthoods would also have taken notice of this. Does the Antikythera device provide for this?
Reply | Report Abuse | Link to thisThank you.
Fantastic article. One calender known in the ancient world and even today is the Hebrew calander also based on the phases of the moon. It also contains both leap months and leap days over a several year period of time. Could the last unidentified gear be a calculation of this? Also to add to Mr. Shamir's comments; given the prominence of the Egyptian calender on the dials it would appear as yet another claim to possible Egyptian origins. How prominent would this calender be in Greece? Perhaps the driving force would be the desire to standardize the various calender systems used in the ancient world? I suspect that if the latitude intended for use or manufacture can be calculated by date and constellation alignment, the coresponding longtitude of a major city/religious site/educational site can be derived by tracing eastward or westward along that latitude.----Dr. Ken Shamir
Reply | Report Abuse | Link to thisMy first thought was in reference to the workings of the gears and all the mechanics involved to reduce friction to workable levels. Have you consulted someone - perhaps a master watchmaker - to examine the level of precision that would have been needed to cause all these gears to work with a minimum of friction drag.
Reply | Report Abuse | Link to thisOverall, this is an amazing device which ought to challenge "modern" humans to see our ancestors as far more intelligent than our own prideful prejudices allow.
I wasn't aware of the Sun's 28-year cycle until I saw your email. I understand that this a cycle of the Julian calendar relative to the week. (There is a leap year every four years and 7 possible days for the start of a year - 4 x 7 = 28). This is related to the belief in Judaism that the Sun was created on a Tuesday and there is a ritual that is spoken every 28 years to celebrate this. I'm not a historian, but I don't think that the ancient Greeks used a seven-day week. In any case, I don't believe that this 28-year cycle is built into the Antikythera Mechanism. I've certainly seen no evidence for it. Many thanks again for the question.
Reply | Report Abuse | Link to thisThe only aspect of the instrument that I know is latitude dependent is the order of the star events on the parapegma (star calendar). The information from this evidence does not appear to be strong enough to made a confident assessment of what latitude the device was made for.
Reply | Report Abuse | Link to thisI don't believe that the Sun's 28-year cycle is included in the instrument in any way - though we never quite know what we will find next! Tony Freeth
Has any research been conducted to compare any of the cycles used or being calculated in the device with those used in the Mayan calendar. Any link may give rise to unknown technical links/ sharing of information between the specialized priests/astronomers/scientists around the globe on several continents in ancient times
Reply | Report Abuse | Link to thisHas anyone considered or done any research comparing the cycles used and or calculated by the device with those employed in the Mayan calendar. Objectively, if the Greeks had the knowledge to create this device, then they surely would also have had knowledge of and from other lands and civilizations around the globe as confirmed by Ptolemy in his various world maps- mappaemundi
Reply | Report Abuse | Link to thisDear SciAm and dear Tony Freeth,
Reply | Report Abuse | Link to thisAlthough I enjoyed greatly your article that thoroughly describes the recent and historical accomplishments in analyzing the intriguing mechanism, I cannot say the same about the depiction of the eclipsed moon at the beginning of your article, because it has the following serious flaws:
1. Corona extending to the dark side of the moon cannot exist, since the moon has neither an atmosphere nor a self-sustained corona similar to the sun. Even the earth’s atmosphere cannot create a brighter corona or halo at the dark side of the moon compared to the one at the bright crescent.
2. The diameter of earth’s shadow on the moon is too small: The earth has around 3.5 times larger diameter compared to the moon’s and this difference was observed in ancient times and used for the first approximations of the true diameter of the moon (and thus of its distance from us). In your illustration the earth’s shadow has a diameter similar to the moons.
3. The color of the sky is too dark for the time of night: Since the moon is very near to the horizon it also means that the sun, on the opposite side, is about to rise (or has just set around 30 minutes ago). This implies that the color of the sky should be a much brighter light blue.
4. For the same reason as in No. 3 much lesser stars should be visible in the sky (if any) due to the dusk or dawn light.
5. Last but not least, I must mention that Michael Wright has often described concrete (or better wooden) evidence of the ancient mechanism’s casing showing a larger back side protruding from the square shaped middle & front casing (as shown in his reconstructions). I do not remember hearing counter evidence to base your aspect of the wooden case’s shape.
Thank you for your time.
Alexandros Argyropoulos
Nea Penteli,
Athens, GREECE
The videos (Parts 1 and 2) on the Antikathera Mechanism in this article are broken links. The videos seem fascinating; I'd sure like to be able to view them....
Reply | Report Abuse | Link to thisBest regards,
Don Weingarten