Google Doodle Celebrates Foucault's Pendulum

Google is celebrating the birthday of French physicist Jean Bernard Léon Foucault today (September 18) with an interactive Google Doodle featuring his most famous invention, the Focault pendulum. A truly elegant scientific device, it demonstrates the rotation of the Earth via a constantly swinging ball and a ring of pegs, each of which is knocked down in succession as the planet changes position. You can play around with the sliders to change how quickly time passes or see how different latitudes affect the pendulum’s arc.

Focault’s other notable contributions to science include an experiment in 1850 which measured the speed of light, the discovery of eddy currents (also called “Faucault currents”), coining the term “gyroscope,” and devising a test for reflecting telescope mirrors that is still used today. For more background and history on Focault, click on the magnifying glass on Google’s home page.

On a personal note, as a kid growing up in L.A. I have fond memories of watching the impressive, mesmerizing Focault pendulum at work in the rotunda of the Griffith Park Observatory and listening to my dad explain the scientific principle behind it. To this day, it’s still one of my favorite places to visit in the city. So, thank you Léon Foucault and Google for bringing it all back to me with this lovely tribute.