Rev 131 - May 8-26, 2010 - Enceladus E10 Options

[Astro0]

An amazing series of image from Cassini.
What about this one
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=216991

[Astro0]

Looking at that Titan image with the rings and Enceladus' surface in the foreground and then at the Enceladus geyser image, I noticed that the horizon on Enceladus pretty much matched up in each image.

So I guess that under the different cameras and lighting conditions, this combined image is what Cassini was heading towards.

[Stu]

So I guess that under the different cameras and lighting conditions, this combined image is what Cassini was heading towards.

G O O D G R I E F...

[brellis]

wow! Cassini is building us a nice library for a virtual tour of the Saturn system.

[Explorer1]

Words fail me yet again!

Cassini, you're gonna make us go nuts if you keep this up much longer!

[Astro0]

Approaching Enceladus - animation (forward/reverse)


Couldn't resist doing an artistic desktop version of the combined image.

[ynyralmaen]

Absolutely amazing images.

Just trying to interpret the plume jet images... although my brain tends to interpret the structure as being in the background, I guess the "lines" oriented towards the 8 o'clock position must be the shadow of Enceladus falling on the jets, so they're actually foreground features, not background, I think.

When oriented with the plume pointed downwards, I guess that means that the large plume jet on the right is all beyond the local horizon and illuminated all the way down to the horizon as seen from Cassini, the middle one straddles the limb so that only part of it is in shadow, while the source of the left-hand jet is in darkness, i.e. closer to Cassini than the limb, and it only becomes visible when it emerges into sunlight. Does everyone else interpret these in the same way?

[Hungry4info]

I agree with your interpretation, ynyralmaen.

[Juramike]

Multiple frame mosaic of Enceladus against the rings in high-phase glory:

[fredk]

the large plume jet on the right is all beyond the local horizon and illuminated all the way down to the horizon as seen from Cassini, the middle one straddles the limb so that only part of it is in shadow, while the source of the left-hand jet is in darkness, i.e. closer to Cassini than the limb, and it only becomes visible when it emerges into sunlight.

I think I agree. One thing I'd add is that it seems like much of the bright plumes aren't in direct sun, but are illuminated by scattered light, perhaps from the sunlit parts of the plume, or perhaps from Saturn. I've indicated with the black arrow a notch in the central bright plume that aligns with the shadow heading off to the lower left. Presumably below the notch (in the image's orientation) the plume's in full sun, and above (closer to Enceladus) it's lit by scattered light:

I'm still puzzled by the appearance of the left plume, in particular why is it's upper right edge oriented the way it is?

And I think I can see the central plume in the Enceladus/Titan/rings frame, circled here:


It's extremely subtle, which I guess is what you'd expect. When the exposure is set for Titan and the rings, the plumes are extremely faint.

[ynyralmaen]

... Presumably below the notch (in the image's orientation) the plume's in full sun, and above (closer to Enceladus) it's lit by scattered light:

Maybe above that notch we're just seeing the part of that jet that's in full sunlight, while the part of the jet nearer to Cassini is in darkness, so the integrated brightness is lower?

I'm still puzzled by the appearance of the left plume, in particular why is it's upper right edge oriented the way it is?

If the shadow of Enceladus is a cylinder, then if that particular jet is oriented so that its long axis (i.e. "along" the sulcus) is close to perpendicular to the axis of the shadow cylinder, I think that odd orientation can be explained. Maybe.

[ngunn]

I'm still puzzled by the appearance of the left plume, in particular why is it's upper right edge oriented the way it is?

And I think I can see the central plume in the Enceladus/Titan/rings frame, circled here:


It's extremely subtle, which I guess is what you'd expect. When the exposure is set for Titan and the rings, the plumes are extremely faint.

On your last point, I agree and I think the other two plumes are also marginally visible in that image.

I don't quite agree about some of the rest however - at least not yet! I do do not think we're seeing plume material except where it's directly lit by the sun. I think the strange shape of the left plume is due to it's lowest part (nearest to Enceladus) being in shadow and invisible. The edge of the plume nearest the centre of the image would be the nearest part to the viewer with more of its lower bit unilluminated. As it snakes off from there towards the horizon less and less of it is in shade and so it appears to descend to meet the surface. (All of this is MUCH easier to picture with the image the other way up!) We saw the same thing on the earlier flyby with plumes apparently detached from the surface of Enceladus where their bottoms were in shade. This is the same, except the sun is now just below the horizon rather than just above, so the viewer is now 'underneath' the shadow edge. ('Down' means towards the ground here.)

Regarding the notch - I think this is due to contrast at the edge of the moon's shadow on more distant E-ring material that we're seeing through and beyond the plumes.

[dilo]

Image composition from Astro0 is a masterpiece!
I made similar version without Cassini, different plumes color and reoriented south pole:

Original images are N00154031 and N00154034... I think this is one of the most spectacular images ever sent by a probe.

Here below also an elaborated version of W00064072 picture (without blooming); you can barely see the plumes in the lower part:

[JohnVV]

And the automatic contrast stretch is probably messing things up

a bit late in the thread but not in time ( Yesterday, 07:27 PM
)

i find that a big problem . and like to do 32 bit tiff's and not 8 bit png's

[Shaka]

Thanks, folks.
Roll over and sigh, Stanley Kubrick.