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,
a clock-like machine consisting of more than
30 precise, hand-cut bronze gears, show it
to be more advanced than previously thought—so
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 had pointers for the sun and moon
— called the "golden little sphere" and
"little sphere," respectively—and markings,
which coincided with the zodiac and solar
calendars.
The back dials, meanwhile, appear to have
been used for predicting solar and lunar eclipses.
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 B.C., but newly revealed lettering
on the machine indicate a slightly older construction
date of 150 to 100 B.C.
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 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 Saturn — the 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 U.K., 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.
