Monday, April 12, 2004

Jupiter's Moons

Easter Monday is a holiday here on Bonaire, so I was able to spend some quality time on the computer processing some images of Jupiter that I took at 4 am. on Sunday, March 28.

Jupiter has four large moons that are easy to spot in a telescope. On the morning of the 28th, three of them were casting shadows on the planets surface at the same time. So if your were a Jupiterian living on Jupiter, you could have seen an eclipse of the sun from three different locations that day.

Jupiter was low in the west by 4 am that morning, so the view in the telescope wasn't that great. Observers further west would have had a better view, and could have seen the event at a more decent hour as well. For example, people in California could see it at midnight. But this was a rare event and I had a good time imaging it.

Here is a montage of images of Jupiter that I took from 3:47 to 4:11 that morning.

The top row of images shows from left to right: Io's shadow, Ganymede, and Callisto's shadow. They are all moving from left to right across the planet disk.

The middle row of images sort of shows what I set out to see: Ganymede's shadow creeping onto the left edge of Jupiter, and then Io's shadow, Ganymede, and Callisto's shadow creeping off the edge of Jupiter on the right side.

The left image in the bottom row shows Ganymede's shadow, Io's shadow, and Io from left to right. Callisto's shadow had definitely vanished off the right side by then.

The right hand image in the bottom row was taken by Gu Yu in West Virginia and clearly shows what you can almost see in my middle row of images. :) The three shadows and Io are labeled on this image.

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