Jupiter Oscillations

A typical procedure in astrophotography involves mounting a camera on a stable platform like a tripod so it doesn’t move during exposures. Some people have motorized platforms that allow the camera to move and track the subject for long exposures of several minutes. I was curious how an image would look for a camera mounted on strings that allowed it to swing forward-backward and left-right at the same time during an exposure. Years ago, this image appeared in a magazine. I kept it and thought of trying it someday.

I didn’t want to hang my good digital camera on strings and risk dropping it. Instead, I used my iPad. This brief video shows it suspended from the handle of my tripod. It was able to swing freely for several oscillations before it damped out. The camera on the iPad is at the far upper corner. One long loop of string held it in place.

The app NightCap Camera was used in the Light Trails mode. I pointed the setup at Jupiter across the dark street. The planet was low in the sky. I started the swinging motion of the iPad, started the exposure with the bluetooth keyboard, and let it oscillate several times. Jupiter shows up in the top center of this image. Other neighbor lights also can be seen at the bottom and left.

Taken with NightCap. Light Trails mode, 18.66 second exposure, 1/27s shutter speed.

For those of you familiar with oscillations in physics, you might recall elaborate patterns traced using motions in the X-axis and the the Y-axis simultaneously. Such patterns are given the name Lissajous figures.

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6 thoughts on “Jupiter Oscillations

  1. Very interesting. When I was a kid we used to use sand bags on a pulley as counter weight to help us into our tree fort. We had it perfected. One time the gunny sack full of sand hit the tree, busted open a small hole, started spinning and spilled sand into an interesting pattern below our fort. Cruder but the same principal I suspect. If someone would have told me there was a science, a formula that would explain it all I would have been all over it. Thanks for the post. I always learn something. Take care.

    • That pulley system sounds fun. Good that you noticed the sand pattern. It has stuck in your brain a long time. … We hooked a long hay rope high in a tree and the other end to the hitch of the tractor. We used the pulley to zip line down to the ground. It’s a wonder we didn’t kill ourselves.

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