Behold, Saturn!

Behold, Saturn!

Behold, Saturn!

Bad Astronomy
The entire universe in blog form
Sept. 21 2009 6:03 PM

Behold, Saturn!


Not getting enough Holy crap! in your life? Then try this on for size:

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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Holy crap!

Oh yes, you definitely want to click on that to embiggen the heck out of it. This teeny 610 pixel wide version does nothing to give you the sense of awe and glory in this spectacular picture. The full size image is a whopping 7227 x 3847 pixels! Warning: you'll lose an hour of your life gaping at it.

That, duh, is Saturn, taken by the ever-amazing Cassini spacecraft. It's actually 75 different exposures stitched together, and was taken on August 12, just a little over a day after Saturnian equinox, when the Sun shines straight along the rings. The illumination from the Sun is about the same everywhere, but on the left the rings are illuminated by Saturn-shine glowing down on them, making them a bit brighter.

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This picture keeps on giving, too. You can spot several moons if you look in the embiggenatisized version (most obvious is Janus on the left; all of the moons have had their brightness enhanced to make them more easily visible in this image). You can also see the subtle swirls and whorls of storms in Saturn's upper atmosphere. And what's that dark line on Saturn's equator? That's the shadow of the rings themselves, narrowed to a thin line due to the Sun angle.

Holy crap.

And yet, there's more. Check. This. Out.

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[Update; Oops: I got this image mixed up with another. I've struck through the old mistake, but leave it up as evidence that I blew it here. It happens sometimes. Sorry about the confusion, and my thanks to Joe Mason CICLOPS Media Relations Coordinator, for pointing out my error.]

This is an old image (taken by Cassini in 2005) that shows a long streak, which I've highlighted with red arrows. New images taken in the past month at Saturnian equinox confirm that this streak is actually an expanding cloud of debris from the impact of a small meteoroid, probably about a meter across and moving at several dozen kilometers/second. It came in almost exactly parallel to the rings, leaving a path of wreckage and destruction many thousands of kilometers long.

This image, also taken at equinox, shows an elongated streak, marked by the red arrows. That streak, it's been determined, is actually from the impact of a small meteoroid, probably about a meter across and moving at several dozen kilometers/second. It came in almost exactly parallel to the rings, As the debris cloud expanded, different orbital motions sheared it, leaving a path of wreckage and destruction 5000 kilometers long. [Update II: My thanks to Carolyn Porco for pointing out this explanation to me in the comments.]

Can I hear one final holy crap?

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The image here was enhanced to bring out the streak. It turns out old images had similar streaks, but at the time they weren't sure what they were.

It's been thought for a long time that the rings were constantly bombarded by interplanetary interlopers, and now we have pretty good proof. This also makes me think this picture of Saturn's rings from August really does show some object slamming into them at speeds dozens of times faster than a rifle bullet.

Cassini has been orbiting Saturn since 2004, and these images show the true power of being able to go to a place and stay there, taking picture after picture for many years. Every picture has a use, and old images can be reinterpreted when new data come in.

And we keep learning! Saturn is a forbidding, remote, fascinating, and enchantingly beautiful world, with secrets and surprises to keep us guessing and fascinated for decades. I'm very glad Cassini is there bring us these delights.