APOD: Bright Spots Resolved in Occator on... (2015 Sep 16)

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APOD: Bright Spots Resolved in Occator on... (2015 Sep 16)

Postby APOD Robot » Wed Sep 16, 2015 4:06 am

Image Bright Spots Resolved in Occator Crater on Ceres

Explanation: What created these bright spots on Ceres? The spots were first noted as the robotic Dawn spacecraft approached Ceres, the largest object in the asteroid belt, in February, with the expectation that the mystery would soon be solved in higher resolution images. However, even after Dawn arrived at Ceres in March, the riddle remained. Surprisingly, although images including the featured composite taken in the last month do resolve many details inside Occator crater, they do not resolve the mystery. Another recent clue is that a faint haze develops over the crater's bright spots. Dawn is scheduled to continue to spiral down toward Ceres and scan the dwarf planet in several new ways that, it is hoped, will determine the chemical composition of the region and finally reveal the nature and history of the spots. In several years, after running out of power, Dawn will continue to orbit Ceres indefinitely, becoming an artificial satellite and an enduring monument to human exploration.

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Anony

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Anony » Wed Sep 16, 2015 4:36 am

I have a feeling these aren't "craters" in the sense that they formed out of some sort of impact. I think they are depressions. Maybe, water exists under a thick frozen crust. Cracks form in the surface and the underlying water escapes, forming a void. The void then collapses leaving what we see - depressions with central crack features with water ice come out. Some of the depressions/craters even have squared off sides and form geometric shapes, as if the depression formed along stress cracks like we see in magma and I think some polar ices here. Finally, some depressions/craters look like they've been moved and modified by forces on the surface.

So, not craters and a non-solid surface.

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Chris Peterson » Wed Sep 16, 2015 4:57 am

Anony wrote:I have a feeling these aren't "craters" in the sense that they formed out of some sort of impact.

I don't know. This looks like a pretty typical complex crater.

Maybe, water exists under a thick frozen crust.

The problem is, there's no plausible explanation for how liquid water could be present in such a small body. Residual heat, radioactive decay, tidal stress - none of these are reasonable options. So unless somebody can come up with a mechanism that allows for a subsurface ocean, ordinary impact craters seem much more likely (possibly modified by uncertain bulk material properties of the surface).
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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby stowaway » Wed Sep 16, 2015 5:03 am

Obviously some kind of open pit mining operation.

Richard Melton

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Richard Melton » Wed Sep 16, 2015 5:39 am

Why does it look like this crater is raised up above the adjacent surface instead of cut down into the surface?

DL MARTIN

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby DL MARTIN » Wed Sep 16, 2015 6:00 am

I'm under the impression that the water on Earth is the result of meteor impact. Could not these bright spots at the base of this crater be frozen water residue from a meteor impact?

Abbey Normal

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Abbey Normal » Wed Sep 16, 2015 6:45 am

Ice

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby geckzilla » Wed Sep 16, 2015 8:15 am

Richard Melton wrote:Why does it look like this crater is raised up above the adjacent surface instead of cut down into the surface?

You're one of the lucky ones. Some craters I have issues doing this with, too. It might help if you view the image rotated 180º.
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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby pedro melo » Wed Sep 16, 2015 8:44 am

My bet is on a Ice Meteor impact

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Boomer12k » Wed Sep 16, 2015 9:17 am

Haze...so vapor of some kind. So, precipitation or condensation of some kind...

Temperature of Ceres...-106.15 C, at average distance from the Sun. -34.15 C, at the closest. No figure for the furthest distance...

So...a substance that vaporizes, and freezes, around those temperatures...
Mechanism...Heat from Sun. Haze seen at Noon....

Crater "appears" to be a depression, not an impact. Why? Note the Top Upper Right crater area...that appears to be a slide of material...not a shot outward as with an eruption, or a strike. This could have been like a collapsed shield volcano or something similar.
Forming as Ceres cooled...

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby stowaway » Wed Sep 16, 2015 12:48 pm

At least one-quarter of Ceres’s mass is water. So it seems likely this is ice. And if a faint haze develops in this crater then why not a hot spot similar to Yellowstone on Earth. Perhaps initiated by the impact that formed the crater weakening the crust and allowing these geyser like outflows or sublimation events. Seems reasonable ;-)

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Joules » Wed Sep 16, 2015 12:55 pm

Higher resolution please.
At 40 meters per pixel it's just not possible to tell if those lines that look like fissures are fissures.
About 0.5 meter per pixel should do the job.
Of course that's months, or more likely, years away, if ever.

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Jarod997 » Wed Sep 16, 2015 1:35 pm

Richard Melton wrote:Why does it look like this crater is raised up above the adjacent surface instead of cut down into the surface?


That's what I was thinking. Even when I rotated the image 180º, it still looked like a raised plateau instead of a crater. It wasn't until I looked a slightly different images of the crater until my head finally flipped the "plateau" into a "crater".

I agree with some other comments, the walls of the crater appear to have very smooth edges, like material has been sliding down the walls - similar to how gravel stockpiles look when they're being formed. This could be just due to the nature of the material, or it could be because the floor of the crater has been sinking or settling. In any case, it doesn't look like a heaved or otherwise traditionally disturbed crater wall. But then again, I'm no crater expert.

MASSpec

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby MASSpec » Wed Sep 16, 2015 2:31 pm

How about a diamond volcano! Obvious high reflectivity, seismic activity, smaller spots are vents, haze is lighter material thrown up causing muted crater interior with land slide walls.

sillyme

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby sillyme » Wed Sep 16, 2015 2:58 pm

I'm thinking it's a big frost heave. An impact created a crater, and melted the ice beneath. When the water froze, it created a frost heave that poked above the rubble.

Not A Crank

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Not A Crank » Wed Sep 16, 2015 3:40 pm

Here's my guess: a way long time ago a comet/asteroid hit the "snowy" surface of Ceres and made the crater. Over many long years the dark interstellar dust collected and settled over everything except that the remnant core of the comet continues to offgas sending up plumes of "snow' along with the bubbles of gas thus creating the white spots on the dark surface. Clearly I'm no scientist but it seems like a plausible explanation to me.

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby starsurfer » Wed Sep 16, 2015 4:07 pm

I think it could be cryovolcanism and maybe a geyser similar to ones on Enceladus are responsible for the haze? Also I wonder what Ann will think of the colour?!

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby ta152h0 » Wed Sep 16, 2015 7:03 pm

Why not let DAWN " spiral in " till crash time, with the camera's rolling ? Orbiting quietly with no fuel indefinitely doesn't sound like discoveries will be made .
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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby daddyo » Wed Sep 16, 2015 8:10 pm

And if there's not enough fuel to crash, how about a highly elliptical one for some dramatic close-ups? Would also be wonderful to produce some 3-d stereo images. Interesting pit to the left.

I wonder what it looks like on the surface in the middle of the frost. Might it be smooth ice, powdered, or maybe crystallized structures. Maybe Superman lives there...
Last edited by daddyo on Wed Sep 16, 2015 8:18 pm, edited 1 time in total.

bub4280

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby bub4280 » Wed Sep 16, 2015 8:12 pm

I'm waiting until someone turns the sensor gain down, then stretches the gamma in the image of just the "mystery white area" until some detail appears.
As it is now, the white stuff just looks over exposed.
Could be a Polar Bear Orgy.

MajorOz

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby MajorOz » Wed Sep 16, 2015 8:28 pm

:lol2:

Obvious to me: It was, in the past zillion years, a "habitat" from.....somewhere.

The apparitions are simply leaking gasses from decomposition.

:lol2:

quigley

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby quigley » Wed Sep 16, 2015 9:05 pm

The vast majority of the fissures (amazingly straight lines) appear near the "bright spots".

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Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Starfish42 » Thu Sep 17, 2015 2:33 am

It's a Planetary Pimple, caused by lack of sunlight and Vitamin D
:roll:

Interested Observer

Re: APOD: Bright Spots Resolved in Occator on... (2015 Sep 1

Postby Interested Observer » Thu Sep 17, 2015 9:15 am

It looks to me to be a recent impact by a body with a solid core. Assuming the top of the picture to be North, the object has come in at a high angle from the SSW.
The impact has sprayed bright subsurface material to the NNE, which can be seen as the smaller bright spots and the "haze" of loose material coating the surrounding area. The most interesting thing to me is that it appears the core of the impacting object has remained intact, landed in the NNE and then rolled towards the large crater wall. In the area which contains the most "haze", there appears to be a divot or track created by the object as it rolled. Subsurface material probably clung loosely to the core as it bounced but was deposited on the surface when the object landed, thus the "haze" is greatest around the divot. The smaller white spots are chunks of the surface which flew in roughly the same direction as the object but were sprayed like snowball shrapnel into a random pattern.

It's also interesting that this shows that while Ceres appears rocky, due to its grey surface colour, it made in fact be totally covered with ice.

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Re: APOD: Bright Spots Resolved in Occator ... (2015 Sep 16

Postby sallyseaver » Thu Sep 17, 2015 9:44 am

Richard Melton wrote:Why does it look like this crater is raised up above the adjacent surface instead of cut down into the surface?


You can get a better look at the crater which is 2 miles deep from this APOD --- and a mountain (4 miles high) that has a white face --- at this NASA page:
https://www.nasa.gov/jpl/dawn/cruise-over-ceres-in-new-video

Here is a picture of the mountain.

Image

I think that this mountain provides evidence against the idea that the white spots in Occator are ice deposited by a meteorite or comet crashing into Ceres.

I am struck by just how white the spots in the Occator crater and conical mountain are. And unlike ice (or diamond), the whiteness does not change with a different angle of the sun as one would expect with a hard surface that is not white but reflecting the full spectrum of light (i.e. white) in certain angles. The sides of the 4 mile high mountain are definitely a different angle from the spots in the crater, but they are still very white.

The spots seem to get brighter with more resolution, but they are constantly very white. Maybe this is just my naivete with respect to probe images taken 915 or more miles away while the sun is shining?

Image

NASA is considering two competing ideas: ice or a "salt."
http://www.space.com/28776-nasa-dawn-ceres-russell-interview.html

Of these two, what do others think this very white, consistently white appearance goes with? It seems to me that this consistently bright white appearance seems to go more with a white "salt" such as meridianiite, magnesium hydroxide or magnesium carbonate rather than ice.


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