Our relationship with the heavens above

Visitors at the Griffith Observatory usually stop at the Los Angeles landmark's soaring central rotunda. There, they pause to watch the giant Foucault pendulum (similar to the one shown above) swing gracefully beneath the famous Hugo Ballin murals depicting classical figures and the advancement of science.

The 240-pound brass ball that moves back and forth on a 40-foot steel cable suspended from Ballin's painted dome is a powerful illustration of Earth's rotation and its relationship with the heavens above.

At Los Angeles' latitude, it takes 42 hours for the pendulum to seemingly complete a circle as the earth beneath it rotates. For decades, that movement has been visually represented by small wooden dowels that are knocked over one at a time by a pointer on the bottom of the shiny gold ball.