Emily LakdawallaDec 26, 2012

Pretty picture: Jupiter photo from an unusual source

One of the reasons I find Twitter so useful is that through the people I follow all over the world, I find out about cool things that I may never had heard of by any other means. Today's example: a nice little animation of a rotating Jupiter and moving Io, shot by Pleiades-1B. (Thanks to Daniel Fischer for the tweet.)

What's Pleaides-1B? It's a French Earth observation satellite that's intended to perform very high-resolution (50-centimeter) imaging of nearly any location on Earth with a daily cadence. It was launched on December 2.

The two Pleaides-1 spacecraft are described as being unusually "agile", in that they can do highly accurate off-nadir point-and-shoot imaging of targeted locations. As one step in Pleiades-1B's calibration and commissioning, it is being pointed at more than 1000 stars -- once again, as they have been for millennia, we steer our ships by the stars. This observation of Jupiter was commanded as part of the commissioning phase.

Jupiter and Io from Pleiades-1B (animation)
Jupiter and Io from Pleiades-1B (animation) A week after its December 2 launch, the high-resolution Earth-observation satellite Pleiades-1B pointed at Jupiter to take this sequence of eight photos. The photos are separated by about 45 minutes and were taken during the calibration and commissioning phase of the spacecraft.Image: CNES / Astrium Services / Spot Image

I did have trouble figuring out which moon was in the animation, because the times given in the caption to the image don't quite match up with reality. It states December 7 between 1300 and 1800 GMT, but the first frame has a moon hidden behind the globe, which then comes out from behind it in the second frame. Io did that at roughly 0939 on December 7. Adding 33 minutes of one-way light time doesn't get me all the way to 1300. It has to be Io, because other moons would appear farther above Jupiter's equator, so I know I have the moon identification correct.

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