The Antikythera Mechanism I
With Java animations by Bill Casselman
Java-animation of The Sun-Moon Assembly
This java animation shows the operation of the
Sun-Moon assembly, that part of the gearing of
the Antikythera Mechanism marked in color
on page 3. The linkage
between the (yellow) sun gear and the (white)
moon gear, determined by the number of teeth
in each gear in the assembly, makes the moon
gear turn 254/19 times as fast as the sun. This
is an excellent approximation of the actual
ratio of their apparent speeds around the zodiac.
In this animation, each step corresponds to
about 7 hours of real time.
It is not known what tokens were used in the Antikythera Mechanism
to represent the sun and the moon on the dials, nor how they were
attached to their gears. In this simulation the sun is represented
by a yellow disc, the moon by a white. The moon's motion follows
the position of the moon gear exactly. The sun moves just like
the sun gear, but in the opposite directon. In the original this
was accomplished by linking a second sun gear to the first by
a vertical, cylindrical gear.
2. The Sun-Moon Assembly