APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by APOD Robot » Wed Oct 26, 2016 4:13 am

Image Propeller Shadows on Saturn's Rings

Explanation: What created these unusually long shadows on Saturn's rings? The dark shadows -- visible near the middle of the image -- extend opposite the Sun and, given their length, stem from objects having heights up to a few kilometers. The long shadows were unexpected given that the usual thickness of Saturn's A and B rings is only about 10 meters. After considering the choppy but elongated shapes apparent near the B-ring edge, however, a leading theory has emerged that some kilometer-sized moonlets exist there that have enough gravity to create even larger vertical deflections of nearby small ring particles. The resulting ring waves are called propellers, named for how they appear individually. It is these coherent groups of smaller ring particles that are hypothesized to be casting the long shadows. The featured image was taken by the robotic Cassini spacecraft currently orbiting Saturn. The image was captured in 2009, near Saturn's equinox, when sunlight streamed directly over the ring plane and caused the longest shadows to be cast.

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ygmarchi
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Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by ygmarchi » Wed Oct 26, 2016 7:04 am

I can't exactly figure out the perspective of the image.

It seams as though there's a sort of fence of structures perpendicular to rings plane,
which I myself find pretty weird to consider.

heehaw

Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by heehaw » Wed Oct 26, 2016 8:44 am

I still am annoyed that they are not going to end Cassini by flying at a low angle "through" a ring.

Guest

Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by Guest » Wed Oct 26, 2016 2:07 pm

ygmarchi wrote:I can't exactly figure out the perspective of the image.

It seems as though there's a sort of fence of structures perpendicular to rings plane,
which I myself find pretty weird to consider.
A two meter tall man will cast a 20 meter shadow at sunrise and sunset.

Boomer12k
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Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by Boomer12k » Wed Oct 26, 2016 2:43 pm

ygmarchi wrote:I can't exactly figure out the perspective of the image.

It seams as though there's a sort of fence of structures perpendicular to rings plane,
which I myself find pretty weird to consider.
It does... it appears to be a solid "fence" of an "Ice Wall"... the jagged chunks casting the shadows. It looks totally different than the other rings and parts of rings... Incongruous.

:---[===] *

jtm196

Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by jtm196 » Wed Oct 26, 2016 5:45 pm

first image ive ever seen that shows any depth to the rings all others are of the flat surface or a thin line

Tekija

Re: APOD: Propeller Shadows on Saturn's Rings (2016 Oct 26)

Post by Tekija » Wed Oct 26, 2016 6:35 pm

Boomer12k wrote:
ygmarchi wrote:I can't exactly figure out the perspective of the image.

It seams as though there's a sort of fence of structures perpendicular to rings plane,
which I myself find pretty weird to consider.
It does... it appears to be a solid "fence" of an "Ice Wall"... the jagged chunks casting the shadows. It looks totally different than the other rings and parts of rings... Incongruous.

:---[===] *
Artist's view: http://www.ciclops.org/media/dv/2014/7978_19123_0.jpg

This is a local feature, not same all along the ring:

Six second movie showing 1 h 40 min: http://photojournal.jpl.nasa.gov/archive/PIA11669.mov

"...an unusual, 20,000-kilometer-long (12,000-mile-long), chevron-shaped structure can be seen moving along the B ring edge. Higher resolution images, taken during equinox, have shown that this region is the site of vertical structures, as tall as 3.5 kilometers (2.2 miles), whose existence was betrayed by long shadows."