The Grand Finale, Proximal orbits |
The Grand Finale, Proximal orbits |
Apr 28 2017, 03:01 AM
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#16
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Member Group: Members Posts: 238 Joined: 15-January 13 Member No.: 6842 |
Excuse my ignorance, but this hurricane is the one at the North Pole, right? Yes. The south pole is currently in the shadows (saturnian winter) and looks like this: -------------------- Curiosity rover panoramas: http://www.facebook.com/CuriosityRoverPanoramas
My Photosynth panoramas: http://photosynth.net/userprofilepage.aspx...;content=Synths |
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Guest_avisolo_* |
Apr 28 2017, 09:17 AM
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#17
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Guests |
I made a gif of the dive!
http://i.imgur.com/i6uMzG2.gifv |
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Apr 29 2017, 09:46 AM
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#18
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Member Group: Members Posts: 238 Joined: 15-January 13 Member No.: 6842 |
Nice colours in this recent view (RGB stack from W00107043, W00107044 and W00107045)
Although I'm not quite sure what we're looking at here. Night side of Saturn with some inner rings? -------------------- Curiosity rover panoramas: http://www.facebook.com/CuriosityRoverPanoramas
My Photosynth panoramas: http://photosynth.net/userprofilepage.aspx...;content=Synths |
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Apr 29 2017, 11:46 PM
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#19
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Junior Member Group: Members Posts: 45 Joined: 27-August 14 From: Private island on Titan Member No.: 7250 |
Enceladus spraying away on April 27. Reminds me a lot of the Io volcano footage from Voyager 2.
EDIT: I didn't realize there would be more to this observation! D'oh! -------------------- aka the Vidiconvict
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May 4 2017, 10:20 AM
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#20
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Junior Member Group: Members Posts: 39 Joined: 9-August 12 From: London, UK Member No.: 6521 |
Not sure if this has been posted, but this movie puts the images in context nicely:
NASA: Cassini's First Fantastic Dive Past Saturn |
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May 4 2017, 01:47 PM
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#21
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
Wildespace said, just above:
"Nice colours in this recent view (RGB stack from W00107043, W00107044 and W00107045) Although I'm not quite sure what we're looking at here. Night side of Saturn with some inner rings?" I think probably the outer rings, E at the top and G in the middle in forward-scattered light, with the limb of Saturn below, and a long exposure. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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May 4 2017, 03:41 PM
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#22
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Lord Of The Uranian Rings Group: Members Posts: 798 Joined: 18-July 05 From: Plymouth, UK Member No.: 437 |
We're looking at the south pole of Saturn (currently in mid-winter darkness), and the G and E rings. In the background is a star field which straddles the Orion / Taurus border:
http://nova.astrometry.net/user_images/1609771#original -------------------- |
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May 4 2017, 04:07 PM
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#23
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Interesting brightness changes on the limb. Is this Saturnian twilight modulated by ring shadows?
-------------------- Steve [ my home page and planetary maps page ]
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May 9 2017, 01:21 PM
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#24
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
With much of the attention on Saturn and the rings, Titan has decided to put on an extra special clouds performance: https://saturnraw.jpl.nasa.gov/multimedia/i...9/N00281060.jpg
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May 10 2017, 12:17 AM
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#25
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Member Group: Members Posts: 214 Joined: 30-December 05 Member No.: 628 |
The background writeup for the cloud picture.
https://saturn.jpl.nasa.gov/resources/7673/ It's good to know that the spacecraft is still able to monitor events at Titan, even with no more close passes scheduled. |
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May 10 2017, 03:42 PM
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#26
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Interesting brightness changes on the limb. Is this Saturnian twilight modulated by ring shadows? The rings do indeed partially block sunlight from reaching the southern border of what would otherwise be the southern boundary of daylight / seasonal darkness. This is suggested by current telescope views of Saturn as seen from Earth and I just confirmed it with the Solar System Simulator's view of Saturn as seen from the Sun. The SSS view of Saturn as seen from below (attached) shows a U-shape, which matches your intuition. Cassini is seeing the tips of the U in a twilight time of day. Thank goodness for the simulator, because it would take pages of trigonometry to work that out from first principles. An interesting consequence is that an observer at the right latitude in Saturn's clouds would see two periods of daylight during this season – morning and afternoon – with a couple hours of "night" during the solar eclipse-by-the-rings around noon. |
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May 10 2017, 11:05 PM
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#27
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Thanks JRehling for that informative discussion with the simulated view. In that I can note an inner U and an outer U. Perhaps we're seeing more of the inner U in the Cassini image, and this U is from the sunlight coming through the Cassini division? The center of the limb is thus shadowed by the A ring and the limb edges (in the image) show sunlight coming through the Cassini division.
As seen from the Sun (and Earth) the outer edge of the A ring thus completely misses the planet while the Cassini Division continues to intersect the planetary ellipsoid. We are really close to the widest open possible with the summer solstice coming up May 24. It then follows that light passing through the Cassini Division would never hit the terminator point nearest the pole. -------------------- Steve [ my home page and planetary maps page ]
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May 11 2017, 02:44 AM
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#28
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
I puzzled over the geometry for a while, trying to simulate, in Photoshop, what the planet looks like behind the rings when it occurred to me that the summer and winter geometries are similar, and the parts of the rings that do and don't cast a shadow on the winter pole are exactly symmetrical with the parts of the rings that do and don't have the planet's shadow cast on them on the summer pole. I've attached an image of Saturn that I took on April 15, which is close to the current situation.
The inner edge of the A ring is slightly in the planet's shadow behind the north pole, but the outer edge is not, so the same situation will apply in the south, where it's harder to visualize what's going on. The Cassini Division will paint a curvy stripe of light on the planet near the winter pole, and that's the inner "U" in the view from below. |
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May 13 2017, 12:26 AM
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#29
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Lord Of The Uranian Rings Group: Members Posts: 798 Joined: 18-July 05 From: Plymouth, UK Member No.: 437 |
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May 14 2017, 08:00 PM
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#30
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
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