Unusual and awesome view of Saturn

By Phil Plait | May 21, 2009 6:38 am

Tom’s Astronomy Blog (you follow his blog, right? Right?) has a picture with an unusual view of Saturn:

Saturn, from Cassini. Click to embiggen

This takes some ‘splainin’! But fasten your seat belt; this one is a bit of a wild ride.

First off, in this picture from Cassini we’re looking down on the rings from about a 41° angle. The sunlight is coming from the left, in a direction from below the rings as seen here. The part of the planet itself we see here is actually in shadow! That’s obvious from the top half of Saturn’s disk, which is dark. However, the bottom part of the disk is being softly illuminated by reflected light from the rings (rather like moonlight can illuminate the Earth). In that case, sunlight came from the left, hit the underside of the rings (underside as seen from this angle that is), reflected off, hit the planet, which then reflected that light back to Cassini’s camera.

The top half isn’t completely dark, though. Light from the Sun is passing through the rings, too. It gets scattered and diffused, and some of it hits the dark part of Saturn at the top of the picture. So we can see that as a faint illumination.

There’s more! The rings look like they’ve been sliced clean; that’s the planet itself blocking sunlight from the rings, so think of that as the shadow of Saturn on the rings. But if you look to the right of that cut, you can see still the rings! They look dark and thin, and you can only see them against the planet’s disk. Some of the light reflected off the planet’s southern hemisphere (which itself was reflected from the rings as mentioned above) backlights the rings where they are in shadow, so you can see them silhouetted against Saturn’s disk.

Wow. What a tortuous way to light an image! But it’s very cool that we have Cassini-on-the-spot to send us lovely images like this. We can simply enjoy their beauty, of course, or we can unravel the pieces of the puzzle (to mix a metaphor) to see what’s really going on here. Both are fun, and both are worth spending time doing.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (27)

  1. MadScientist

    Are the three large spots in the rings moons or cosmic/gamma rays illuminating pixels?

    Awesome picture though; that one was screwing with my head.

  2. and what is that little tiny white dot in the lower right of the image?

  3. Hey, I can see USS Voyager gliding over the rings, its image reflecting from the tiny ice particles! *drinks more coffee*

  4. Oded

    Isn’t Saturn’s rings right now edge-on to the sun?
    Shouldn’t there be very little light if at all on the rings? Is this an old image? If not, then I’m not sure I understand the picture correctly.

    Still, very cool!!

    Edit: I just saw in the details that this picture is from March 2009… Then I’m not sure I understand the angle of the light on the rings and reflection to bottom half of Saturn… In this picture, is the sunlight coming from below the rings?


    The rigs are what Saturn is most famous for!

  6. Geek Goddess

    I think I see the Fithp ship

  7. Big Al

    Read the referenced Tom’s entry, it explains what the bright dots are.

  8. Evil Eye

    My only question is why does it take so long for NASA to publish photos these cool?

  9. JAK

    If the sunlight is coming from beneath (left bottom corner of the picture?) then how come we see the rings illuminated from the angle the picture was taken?

    Are the rings reflecting the light at perpendicular angle? Since Cassini is at 41 degrees and assuming that light is coming at about 49 degrees from bottom left (of the picture).

  10. dre

    Tom said that the Cassini team said, “Bright spots in the image are stars occulted by the rings.”

  11. I think I see the Fithp ship

    Hah! Awesome.

  12. @ EvilEye:

    My only question is why does it take so long for NASA to publish photos these cool?

    They are available practically as they come in from the spacecraft on the Cassini website.

    Of course, they have to have all the flying saucers and plasma currents expurgated before they are released to the public.

  13. mike burkhart

    I like this and all views of saturns rings but I would like a probe to get so close that it could get a picture of the ice and rock particles that make up the rings . They have been portrayed in some scifi movies like Silent Running and I would like to see how accurate the movies are.

  14. Mike

    Its ironic that the organization that honored Forrest Mims (Discover magazine and associated blogs) has no mention of the recognition being given Eugenie Scott. http://pandasthumb.org/archives/2009/05/genie-scott-hon.html#comments

  15. DrFlimmer

    @ kuhnigget

    That is exactly what happens ūüėÄ

  16. Torbjörn Larsson, OM

    Nice gams.

    I think I see the Fithp ship

    So we can get started on an Orion again?

    ‘Thor is knocking, and he really wants in.’

    [OT: PZ teases PP with not (?) noticing Creation Astronomy. Apparently astronomy is a corrupt “evolutionary” “model”:

    Spike Psarris was previously an engineer in the United States’ military space program. He entered that program as an atheist and an evolutionist. He left it as a creationist and a Christian.

    This site is dedicated to exposing the bankruptcy of the evolutionary model, especially in astronomy.


  17. Actually, Mike, it would make more sense to email me with a suggestion like that, dontcha think?

    In fact, I did wrote up a post for JREF’s Swift, and simply forgot to crosspost it here on my blog. :) I’ll take care of that forthwith.

  18. Torbjörn Larsson, OM

    @ Mike:

    Its ironic that the organization that honored Forrest Mims (Discover magazine and associated blogs) has no mention of the recognition being given Eugenie Scott.

    That Mims business is interesting. I see that you have raised the issue before, and that the Discover Web Editor replied:

    @Mike, re: DISCOVER giving a shout-out to amateur scientist Forrest Mims, who also happens to be a fellow of the Discovery Institute:

    Here’s a letter from the editors that’s running in the February issue, which is coming out soon:

    In our feature, we recognized Mims specifically for his contributions as an amateur scientist, and we stand by that assessment. His work on the Altair 8800 computer, on RadioShack‚Äôs home electronics kit, and on The Citizen Scientist newsletter has been undeniably influential. DISCOVER does not in any way endorse the Discovery Institute‚Äôs views on ‚Äúintelligent design.‚ÄĚ At the same time, Mims‚Äôs association with that group does not invalidate his role as a leading figure in the American amateur science community, any more than James Watson‚Äôs dubious speculations about race take away from his groundbreaking research on DNA.

    The thread references the paper magazine, and I can’t find any pro or con mentioning in the blogs. Personally I would not include Mims as a scientist worth his title after his personal attack on biologist Eric Pianka (in 2006) where he alleges that Pianka advocated genocide in a speech.

    It seems clear that Pianka did not, but described a likely population crash that would follow if overpopulation ensues, an old scientific idea going back to Malthus.

    Mims also strayed outside of science proper when he subsequently disapproved that the Texas Academy of Science awarded Pianka with a plaque naming him “2006 Distinguished Texas Scientist”. It is not unheard of that professional scientists behave improperly in similar manner, but as Mims is a free ranging amateur his honorary position should be judged precisely by his science and his conduct.

    OTOH, that business is not in any way coupled to Scott. (Maybe that is the real irony.) Further, to try to make that connection is to raise an issue that has already been resolved. I.e. Discover stand by their assessment, others would assess matter differently.

    And on the separate issue of Scott’s honors, why would Discover in any way want to mention a recognition made by another magazine (Scientific American)? Phil might though (so I see ;-).

  19. gar

    Another gem from the Master Probe. Bravo!

  20. Fake. I can see the strings. And there’s no, er, stars. Yeah.

    This proves my theory that Saturn is made of rubber ducks 100%. ūüėõ

  21. Elegiac View

    Arik Rice, I suggest that you think a moment before saying such a thing.

    This is a photograph, no? Therefore, photographs can be subject to certain techniques, such as lighting, positioning, etc.

    I also would very much doubt that Discover Magazine would post a ‘fake’ image on their site.

  22. You can see Discovery, over in the bottom right corner! Hello, HAL!

  23. flawedprefect

    Hey Dr Phil (ie: the GOOD Dr Phil, not he one who calls people “IDIOT”… except for maybe antivaxxers).

    As a 3D artist, I am attempting to recreate this lighting phenomena in 3D based on your description. You’ve given me enough clues to place my lighting, so I would be happy to email you the results, just so we can see how it works.

    Note: While 3D effects are synonymous with “fakery”, seeing how the situations are faked con provide very real insights into how natural phenomena work. Stay tuned!

    Paul C

  24. Crux Australis

    flawedprefect: we’d all love to see that animation when you have it!

  25. fauxlish

    Embiggen is a perfectly cromulent word…


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