https://www.space.com/gravitational-waves-lunar-year-cosmic-clock-antikythera-mechanism
Fresh research about ripples in the fabric of spacetime suggests a nearly 2,000-year-old cosmic calculator followed the lunar calendar instead of the solar one.
The hand-powered "Antikythera mechanism" was retrieved in pieces from a sunken shipwreck in the Aegean sea in 1901, sparking more than a century of research into how this device was made — and why. The box-shaped mechanical computer used gears and dials to track ancient astronomical events such as solar eclipses and the movements of planets.
Now, researchers are using cutting-edge work surrounding gravitational waves, which are ripples in spacetime sparked by events like black hole mergers or collisions between stars, to help uncover the mechanics of Antikythera's Ancient Grecian gears. (The device is named after the Greek island near where it was found.)