April 2, 2011

the Antikythera mechanism

The second century B.C. astronomical calculator found in a shipwreck off the Greek island of Antikythera was even more sophisticated than thought.

Earlier research showed the device also accounted for a subtle weirdness in the motion of the moon. Because the moon’s orbit around the Earth is an ellipse, not a perfect circle, the moon seems to speed up and slow down over the course of a month. In 2006, Tony Freeth of Cardiff University and colleagues showed that a clever configuration of two overlapping gears, with the top gear laid off-center from the bottom gear, could give the moon’s marker its irregular speed.

Because of the Earth’s elliptical orbit around the sun, the sun makes a similarly variable trip across the sky, speeding up and slowing down over the course of the year. But the effect is much more subtle than for the moon.

comments

  1. fin on April 5th, 2011 at 12:38 pm

    thats so damn cool…