Houston Museum of Natural Science's Foucault Pendulum has stopped after decades

[Buster's Uncle]

Houston Chronicle
Houston Museum of Natural Science's Foucault Pendulum has stopped after decades of swinging. Here's what happened.
Ralph Green
Sat, December 13, 2025 at 7:00 AM EST
2 min read



The Foucault Pendulum at the Museum of Natural Science Feb 27, 2008. Wednesday, Feb. 27, 2008, in Houston. (Eric Kayne/Houston Chronicle)


Houston Museum of Natural Science's Herzstein Foucault Pendulum has stopped after decades, and museum visitors are wondering why.

The pendulum at the museum is attached to a 61-foot-long cable. It typically swings as the Earth rotates, knocking down pegs, until it suddenly stopped this month.


Why did the Foucault Pendulum stop?

The Houston Museum of Natural Science posted on its TikTok account that its Foucault Pendulum stopped swinging this month.

In the video, HMNS' Johnny Hemberger said all pendulums need a nudge to counteract mechanical friction and air resistance. At HMNS, that nudge comes from an electromagnetic tug at the top of the cable from a metal collar, which moves only in the same direction the cable travels.

He said it is rare to see the pendulum stop, but it needs a mechanical fix.

"In our case, this mechanism has stopped," Hemberger said. "Because, like all mechanical things, it needs maintenance from time to time, especially after literal decades of virtually nonstop operation."

Hemberger said the pendulum will be soon working again.

The museum posted another video this week telling visitors and followers it is in the process of fixing it.

"Enjoy the rare phenomenon while it lasts," the caption said, referring to the stopped pendulum.


What is the Foucault Pendulum?

The Foucault Pendulum was invented by French physicist Jean Bernard Léon Foucault, who first presented it in 1851 in Paris, according to HMNS.

It demonstrates the Earth's rotation: The pendulum does not actually change direction; instead, the Earth rotates beneath it.

This article originally published at Houston Museum of Natural Science's Foucault Pendulum has stopped after decades of swinging. Here's what happened..