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I have a question about this Cassini Saturn image., This may be a remedial question, and for that I apologize.
Phil Harwell
post Aug 11 2022, 11:27 PM
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Hello, Iím new here. This may not be a productive question, but itís been nagging me for a while.

After a life of ignorance and doubt, I have re-embraced my love for all things space-related recently. I started by looking at Cassini images. I came across this image, which looks great, but then I remembered that Saturnís rings are only one kilometer thick. The thought occurred to me: if the rings are that thin, how in the universe are they visible from this far away? I donít remember the distance, but itís millions of kilometers away, so I would think they wouldnít be visible from that distance, unless youíre seeing them at an angle.

Iím sure this is a simple answer, but Iím not knowledgeable enough. Thanks for allowing me to join the forum, and thanks for taking my question.


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Hungry4info
post Aug 12 2022, 02:30 AM
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It is indeed viewed at an angle. You can see this when the ring goes behind the planet.
Attached thumbnail(s)
Attached Image
 


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Phil Harwell
post Aug 12 2022, 03:44 AM
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Oh okay. I totally didnít see that. Thanks for pointing that out! I can finally rest easy. 😄 It can now go back to being one of my favorite Cassini images.


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StargazeInWonder
post Aug 12 2022, 07:14 AM
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Additionally, a feature does not have to appear >1 pixel (in this case, in width) to be visible. Stars are visible in, say, HST photos, but are much smaller than 1 pixel, but are very bright. An object that resolves to <1 pixel will still have an effect on the brightness of pixels and so can stand out from the background as a visible feature if the contrast is great enough.
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JTN
post Aug 12 2022, 11:32 AM
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See also http://satobs.org/tss.html -- a 2.54mm-wide (but rather long) string apparently easily visible from hundreds of km away.
(The angle of which is a couple of orders of magnitude smaller than notionally 1km-wide rings would be seen edge-on at the distance of the above picture, 3.2 million km.)
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