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Jupiter and Moons
An animation of the planet Jupiter and four of its moons. CREDIT: Stuart/Chris
With Jupiter and Venus currently approaching each other on the sky (in reality they are about 750 million km apart), it prompted me to have a hunt through the limited selection of images that I've taken of the king of planets.

On the right you should see a short animation which Chris and I made on a cold November night back in 1999. We were observing with a Meade LX200 and thought we would try to make an animation of Jupiter's moons by taking a series of shots once every 15 minutes. We picked 15 minutes because that would give us time to look at other stuff between shots and we thought any more frequently would be overkill. At the outset we had no idea how many frames we would get because the weather isn't terribly reliable around here. It turned out to be one of the best nights of the winter and the best observing night I've had in the middle of Manchester. We observed Jupiter until it got too close to the horizon at around 4 am. To round things off we even managed to spot an Iridium flare in the dawn sky. I got no sleep that night and I had to attend five hours of lectures from 9 am. It can be difficult to concentrate on a physics lecture when you've been awake for 26 hours!

The following day, I loaded the images onto the computer and aligned them all by hand. I then inverted the colours (black on white is easier to see than white on black) and put them into an animation programme. I have added some labels to the first frame so that you see which moon is which (left to right: Callisto, Io, Ganymede and Europa). The vertical band is due to the fact that Jupiter was so bright - so many electrons were liberated in the Jupiter pixels of the CCD, that they overflowed into neighbouring pixels in the readout direction (up and down).

The frames aren't of the highest quality but I love the fact that you really can see the moons move around Jupiter - recreating one of the famous observations of Galileo. I'm sure there are some of you out there with better telescopes and/or clearer skies than I had. So I challenge you to do this yourself.

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Posted in astro blog by Stuart on Wednesday 31st Aug 2005 (09:48 UTC) | Permalink
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