Scientists Unravel Mystery of Ancient Greek
Machine
Ker Than
LiveScience Staff Writer
LiveScience.com Wed Nov 29, 1:25 PM ET
Scientists have finally demystified the incredible workings of a
2,000-year-old astronomical calculator built by ancient
Greeks.
A new analysis of the Antikythera Mechanism [image], a clock-like
machine consisting of more than 30 precise, hand-cut bronze gears,
show it to be more advanced than previously thoughtso much so that
nothing comparable was built for another thousand years.
"This device is just extraordinary, the only thing of its kind,"
said study leader Mike Edmunds of Cardiff University in the UK.
"The design is beautiful, the astronomy is exactly right
In terms
of historical and scarcity value, I have to regard this mechanism
as being more valuable than the Mona Lisa."
The researchers used three-dimensional X-ray scanners to
reconstruct the workings of the device's gears and high-resolution
surface imaging to enhance faded inscriptions on its surface.
Precise astronomy
The new analysis reveals that the device's front dials [image] had
pointers for the sun and Mooncalled the "golden little sphere" and
"little sphere," respectivelyand markings which coincided with the
zodiac and solar calendars. The back dials [image], meanwhile,
appear to have been used for predicting solar and lunar eclipses
[image].
The researchers also show that the device could mechanically
replicate the irregular motions of the Moon, caused by its
elliptical orbit around the Earth, using a clever design involving
two superimposed gear-wheels, one slightly off-center, that are
connected by a pin-and-slot device.
The team was also able to pin down the device's construction date
more precisely. Radiocarbon dating suggested it was built around 65
BC, but newly revealed lettering on the machine indicate a slightly
older construction date of 150 to 100 BC. The team's reconstruction
also involves 37 gear wheels, seven of which are
hypothetical.
"In the face of fragmentary material evidence, such guesswork is
inevitable. But the new model is highly seductive, and convincing
in all of its detail," wrote Francois Charette, a researcher at the
Ludwig-Maximilians University in Germany who was not involved in
the study, in a related article in the journal Nature.
Discovered in 1900
Pieces of the ancient calculating machine were discovered by sponge
divers exploring the remains of an ancient shipwreck off the tiny
island of Antikythera in 1900. For decades, scientists have been
trying to figure out how the device's 80 fragmented pieces [image]
fit together and unlock its workings.
Previous reconstructions suggested the Antikythera Mechanism was
about the size of a shoebox, with dials on the outside and a
complex assembly of bronze gear wheels within. By winding a knob on
its side, the positions of the sun, Moon, Mercury and Venus could
be determined for any chosen date. Newly revealed inscriptions also
appear to confirm previous speculations that the device could also
calculate the positions of Mars, Jupiter and Saturnthe other
planets known at the time.
The international team, led by Edmunds and Tony Freeth, also of
Cardiff University, included astronomers, mathematicians, computer
experts, script analysts and conservation experts from the UK,
Greece and the United States.
The researchers plan to create a computer model of how the
Antikythera Mechanism worked and eventually a working
replica.
The team's findings will be presented in a two-day international
conference in Athens and published in the Nov. 30 issue of the
journal Nature.