Google Doodle Honors Physicist Léon Foucault, Shows How the Earth Spins

The famed Frenchman, who would have turned 194 today, devised a pendulum to demonstrate our planet's rotation. Google's interactive version lets you see how it works

Today’s Google Doodle celebrates the life of the nineteenth-century, French physicist Léon Foucault, and features one of his most impressive inventions: the Foucault pendulum.

Back in the 19th century, it was well known that the earth rotated on its axis, but scientists had struggled to find a simple way of demonstrating this concept. Some particularly ambitious researchers tried dropping weights from high altitudes, or even launching a cannon balls vertically upwards and hoping the earth rotated sufficiently while the projectile was airborne that the ball’s launch point and landing point would deviate in a measurable fashion.

Luckily, before anyone could get seriously injured by these types of experiments, Foucault came to the rescue. He devised a stunningly-elegant test using a multi-directional pendulum. The pendulum would be released over a thin layer of sand, at such a height that the pendulum’s bob would barely graze the top of the sand, in a path that looks like this:

DemonDeLuxe / WikiMedia

While it might look like the pendulum is changing direction while the surface stays static, it’s really the other way around. The earth is spinning, and that movement is ever-so-slowly moving the sand placed under the pendulum’s path.

Today’s Google doodle demonstrates two aspects of this phenomenon. First, it shows how the earth moves under the pendulum. Second, it shows how the speed of the pendulum’s apparent movement depends on where the experiment is held. (The further from the equator the pendulum is placed, the faster it will seem to move around a circle. The closer it is to the equator, the less it appears to move at all, because both the device’s bob and the earth are rotating on virtually the same plane.)

If this all seems a little complicated, well, that’s what the doodle is for! Try messing with the time of day and different locations to get a feel for how the experiment works. The doodle automatically detects where you are currently located, but you can alter that by moving the slider above the globe icon. Want to learn more? This Dartmouth professor does a great job explaining the science behind Foucault’s invention.

It’s also fun to watch one of these pendulums in real life. The United Nation’s headquarters has a permanent display, as do various museums around the world. Here’s a neat demonstration from the Oregon Convention Center:

BaronessGabi

Why is the reflection of the pendulum within the "glass" on the photo being shown?

BaronessGabi

I desperately want this beautiful thing in my home... as well as the two dimensional sundial-type that appeared on my computer screen - Chrome. Hell, it's gone now...

ANYBODY KNOW how to get it back?  Anybody know WHERE the "interactive" is?

easolinas

Yet more evidence that the people letting us look for lolcat pictures are more intelligent, educated and cultured than the people who officially run the country (whose response to the pendulum would be "I don't know what it is, but we have to either tax it or use it to fight a useless war!").

DKqwerty

I did a science project for my 9th grade Earth Science class (1999) using a Foucault pendulum to prove that the Earth rotates. Basically, I let a pendulum made from a plumb bob swing for an hour while JUST grazing the contents of a tray of sand. After an hour, measured the degree of rotation in sand, did a bit of trig, and proved that YES, the Earth rotates over a period of about 24 hours! I won an honorable mention.

getmeouttaky

Not to be too picky but is that thing working right?  I thought the pendulum hit the pins at cross angles.  It looks like this one is aiming at  both pins to the top of the circle, which I would think means that the crossing is always unequal.

leguennec

fantastique, le pendule de Foucault, quelle merveille, l'icône en page d'accueil......merci beaucoup pour cette ingéniosité....j'espère qu'il ne disparaîtra pas trop vite.....

magee92

people are stupid he was just trying to change the worlds look upon science for the better

injoyinlyfe

I hope we all understand that this mans view is skewed by his devotion religion

injoyinlyfe

This guy is trying to convince the scientific community that the earth is flat based on the teachings of a religious guide; the Koran. That is almost like trying to say it is scientifically possible to grow another race of human from another's rib as eve was created in the bible. So if we try and draw fact from religion all we get is scribbles, it is in belief where religion truly belongs

UNHR217A3

Inside Job by Charles Feruson

kvonfeldt

Thanks Again Google for another Great tribute to Real Science...

klun0023

At 2:40 she says the earth is changing the movement of the pendulum. It's actually the other way around. The pendulum stays the same and the earth is moving under it.

upwind911

Mine too

must be no Dilbert on staff to correct the graphic artist

ftastronaut7

@magee92 YOU\RE THE STUPID aSS onE...BET YOUR DUMB ASS DIDN'T EVEN KNOW What a pendule was DUH

BCOOK83

@injoyinlyfe                                                                                                                                                   Fool..............his religion was science and he was devoted to just that. If you bothered to read about him, you would see he did not return to his roots, the Roman Catholic Church, until the very end of his life. Always joyful when one of ours returns to the fold...no matter how late.

PatrickSewell

@injoyinlyfe Wow you're extremely insecure, if you really believe your life means less then a stick of gum and you're so idiotic you really believe that when you die you'll be all dressed up and nowhere to go doesn't mean you go on here a make a complete fool of yourself. But keep do so everyone can laugh at yet another immature insecure Atheist.

DianeMarshall

@klun0023 I would like to agree but I don't believe Earth swings back & forth. Help me out here... ;)

wurmanx

@klun0023  It's important to note that the fulcrum of the pendulum is also still actually attached to the Earth and is affected by both the rotation of the Earth on its polar axis and by the revolution around the Sun. It is the length of the pendant that allows more or less degrees of freedom for the bob. The concept(s) of the pendulum were known long before Foucault, as in clock designs, but his decision to select a 27 meter wire pendant made the difference. The Earth does change the positions of the bob although it is negligible to the eye. Even so, in the course of a sidereal day, it becomes obvious in the patterns made by the bob.

DKqwerty

@wurmanx How? Inertia would suggest that it continues on its straight trajectory until acted up by an outside force. Other than possible friction at the point that connects it to the ceiling (which should be infinitesimal compared to the inertia of such a mass), what outside force is moving it off its inertial trajectory? (Not trying to be contentious, I'm just curious!)

jjratfish

@DKqwerty @wurmanx You answered your own question.  Nothing moves it off it's trajectory as noted above.  It stays on the same trajectory and the earth spins whatever reference point is underneath it.