11 years of Saturn photography

The Wall Street Journal downloaded the freely available raw image files of every picture Cassini has taken while at Saturn and collated them together into one gigantic video.  The pictures flicker past extremely fast, but even so, Cassini has taken a heck of a lot of pictures; the whole video is a whopping three hours and forty-eight minutes long!  This spacecraft’s-eye view really drives home how long this spacecraft has been plugging away out there.

And the mission isn’t even over yet!  They’ll have to put out a “part two” when the mission is complete.  😉  So go ahead and watch this video, or more realistically, flick through it for a bit.  You notice a few interesting things.  WARNING: the flickering as the images change is fairly intense at times; if you have epilepsy, consider carefully before viewing.

  1. All the images are black and white, but they change tone dramatically, and flicker in a very predictable pattern.  Cassini produces color images by taking the same image with its black-and-white camera several times, but with different color filters in front of it (not all of which are discernible to the human eye; Cassini has a broader range than we do).
  2. Over time, the shadow on the rings changes.  Cassini arrived near a solstice, so the rings appeared “open” from our perspective; like Earth, Saturn has a significant tilt to its rotational axis, and this means that at solstice, Saturn’s shadow doesn’t stretch all the way across the rings.  Then watch as the years go by, and the shadow lengthens, and the shadow of the rings on the face of Saturn slips further towards the equator and thins until, at solstice, the rings appear to have a chunk missing and the ringshadow is a razor-thin line across Saturn’s equator.  This is the equinox.  Then, the pattern reverses, as the other pole moves towards summer solstice and the other slips into darkness, and the shadow of Saturn recedes across the ringplane.
  3. You get an idea of the sorts of observational priorities they go through, and also get a glimpse at how Cassini’s orbit has changed through the years, as it shifts from target to target, and you can see when there are shorter or longer exposures (the longer exposures produce star trails, as Cassini pivots to keep its target firmly in focus).  Saturn grows and shrinks, though note that it does shift between the narrow-image and wide-image cameras.  You can see moons grow closer and become the focus of intense scrutiny during the flybys.  It’s an interesting look at Cassini’s eleven years in Saturn orbit.

And now, if you’ll excuse me, I have some Doctor Who to catch up on….


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