Foucault Pendulum in the Griffith Observatory Rotunda

Griffith Observatory

Foucault Pendulum at the W.M. Keck Foundation Central Rotunda – Griffith Observatory

If you’ve ever been to the Griffith Observatory, you of course have seen this large Foucault Pendulum as you enter the main building. It swings slowing from each end of the circular area demonstrating the Earth’s rotation to the visitors.

According to the Griffith Observatory’s website, the brass ball weighs 240 lbs and is suspended by a 40 ft long cable. It then:

“swings in a constant direction while the Earth turns beneath it. The pendulum is mounted to a bearing in the rotunda ceiling that does not turn with the building as it rotates with the Earth. A ring magnet at the bearing gives a little tug on each swing of the pendulum to keep the pendulum in motion. As the day passes, the pendulum knocks over pegs set up in the pendulum pit and indicates the progress of rotation”

Interesting isn’t it? If you wait and watch if for a while you’ll see exactly what it’s trying to prove.

Here’s a tip, take your time when you’re at the Observatory, like the pendulum rushing your visit will limit the amount of fun and knowledge you’ll get out of it.

My wife and I make it a habit to visit at least once a year. You never know what you’ll find. For example, not too long ago we captured a crazy stunt as a man walked out onto a roof ledge in order to plank on the side of the Griffith Observatory.

As for the picture above, capturing the moving pendulum in low light is a challenge.  The only option is to use a high ISO or a flash. I chose to go with a high ISO of 1250, a flash would have produced shadows and uneven light.

If you look closely (viewing the larger image) you can see that the ball needs a little dusting, the specs are visible. Plus, my reflection and that of the visitors are also seen on the top of the ball. I’m the one with the camera on the lower right next to the blue color coming from the open front main door.

Planking at the Griffith Observatory


Planking at the Griffith Observatory at sunset.

Earlier today while visiting the Griffith Observatory with my wife, we noticed two guys setting up for a risky and very dangerous planking stunt. One was the “plankee” (?) and the other was setting up to take the photo. It required the guy to climb over a wall and down a roof while his friend took the image from my right (off the right side of the image, not shown).

I noticed the two setting up, so I quickly positioned myself for the shot. A security guard came just before he was going to jump over, so he waited. But as soon as he was gone, the stunt started. He jumped over the wall and ran over to the ledge. He “planked” for about five to eight seconds at the most. I managed to get five shots with my Nikon D7000 and on-camera flash. I’m assuming his friend also captured the moment with his camera.

Because there is a security (seen on the upper right side of the photo), the security guard quickly returned. The two men casually left the roof of the observatory and blended with the visitors. I walked over to the north side of the roof, facing the front of the observatory and the two men were casually walking away. Seemed like a risky but successful planking operation.

I don’t know who these two men were, nor do I endorse EVER doing something like this at the Griffith Observatory, as any small slip could have easily turned this innocent stunt into a story on the 11 o’clock news!

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