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grapes
2015-Feb-26, 12:03 PM
This pic is almost too good to be true! :)

http://www.nasa.gov/sites/default/files/thumbnails/image/pia19185-cr.jpg

http://www.nasa.gov/jpl/dawn/bright-spot-on-ceres-has-dimmer-companion/

antoniseb
2015-Feb-26, 12:24 PM
Almost... but I'm pretty sure it is true.

iquestor
2015-Feb-26, 02:17 PM
Are there any explanations at all about what they are?

Spacedude
2015-Feb-26, 02:44 PM
It should be obvious that there are 2 possible explanations :

Ceres is hollow and those glowing spots are the rocket exhausts.
or
The sun is glinting off of 2 giant saucers presently on the surface.

Another likely 3rd explanation is that my wife served me decaf this morning.
We should know which one is the correct answer in a few days.

Zartan
2015-Feb-26, 02:56 PM
They are 'high albedo features'... Lakdawalla discusses about them (among other stuff) here (http://www.planetary.org/blogs/emily-lakdawalla/2015/02251857-ceres-geology.html).
They are not necessarily exceptionally bright, just appear that way since Ceres is pretty dark overall. Nevertheless, such a high albedo contrast seems bit unusual. Obvious answer is that it's brighter material excavated by fresh impact, but this is somewhat problematic as they don't look much like bright impact features on other bodies.
With low resolution pictures as we've had so far, high albedo features become oversaturated and may appear much bigger than they really are, compare this old Hubble pic (http://upload.wikimedia.org/wikipedia/commons/3/33/Ceres_Hubble_sing.jpg) for example.

The dark 'Piazzi' feature seen in old HST and Keck images is not really showing up in Dawn images. Guess they'll name the big, flat crater 'Piazzi'...

Ara Pacis
2015-Feb-26, 06:25 PM
My first impression is it's an optical artifact. Have they ruled that out?

What sort of volcano? I think I remember reading that Ceres was thought to have an ice mantle, so could it be an ice volcano?

trinitree88
2015-Feb-26, 07:53 PM
mmmm.It's snow from Boston....gotta put it somewhere...SEE:http://boingboing.net/images/_images_blog_2009_06_Digger1.jpg

Zartan
2015-Feb-26, 08:10 PM
My first impression is it's an optical artifact. Have they ruled that out?


What kind of 'optical artifact'? Instrument error has been ruled out even before Dawn.



What sort of volcano? I think I remember reading that Ceres was thought to have an ice mantle, so could it be an ice volcano?

Seems plausible otherwise but what would power it? There is no tidal interaction from large nearby body present. OTOH didn't spectral analysis detect some slight water outgassing so I guess anything's possible.

It occurred to me that IF alien structures (say, some sort of station) actually were present somewhere in our Solar system, this is probably how they would look from distance: compact albedo anomaly. OTOH, we would have probably noticed weird spectra before this :)

Swift
2015-Feb-26, 10:30 PM
It should be obvious that there are 2 possible explanations :

Ceres is hollow and those glowing spots are the rocket exhausts.
or
The sun is glinting off of 2 giant saucers presently on the surface.

"Glorn... where did you park the spaceship?"
"On Ceres; the humans never go there. Why?"
"I think you left the headlights on"

Buttercup
2015-Feb-26, 10:33 PM
I've seen (a news source) these options proposed:

1. Venting from ice volcano(es).
2. Salt.

Zartan
2015-Feb-26, 10:52 PM
Closest comparison to Ceres is probably Umbriel (http://en.wikipedia.org/wiki/File:PIA00040_Umbrielx2.47.jpg). Similar size, dark body with few very bright features. Alas we have only few decent pics on Umbriel. Of course, composition-wise they're not that similar.

Ara Pacis
2015-Feb-27, 05:26 AM
What kind of 'optical artifact'? Instrument error has been ruled out even before Dawn. Dunno. Not saying it is, just that it's what it looks like. The way it lined up along pixel lines in the image but with lower intensity looked suspicious. But that's based on only one image I've seen.


Seems plausible otherwise but what would power it? There is no tidal interaction from large nearby body present. OTOH didn't spectral analysis detect some slight water outgassing so I guess anything's possible.

Unless there's still residual heat from formation or radioactivity.

Spacedude
2015-Feb-27, 02:46 PM
Coming down the home stretch I'll place my final bet on fresh impact craters. That Ceres is a basically lump of dirty ice (rocky core surrounded by a frozen ocean) and the impacts create a lake of sorts that flash freezes into white ice (white as compared to the rest of Ceres surface). Over time the older white ice craters are covered with a thin layer asteroid belt dust which blends them in with the rest of the surface color. Taa-Daaa!

grapes
2015-Feb-27, 03:31 PM
Yeah, that's the most obvious explanation.

It can't be an artifact, or at least the bright spot can't be an artifact, because it was in other images--dividing into two, though, who knows?

Woos are already latching onto it, which is a good thing. We're going to get a lot better images over the next few months

iquestor
2015-Feb-27, 04:50 PM
Woos are already latching onto it, which is a good thing. We're going to get a lot better images over the next few months

It will be really cool to see the close up images in March and April, and see what's going on. Likely its salt, or ice, or something similar as proposed above.

Ross 54
2015-Feb-27, 06:08 PM
The idea that the bright spots are flash-frozen lakes, made of water from a subsurface Cerean ocean, and exposed by fresh impacts, has a few problems.
We must first assume that a subsurface ocean actually exists. Water vapor plumes have been detected on Ceres, but these intensify when this dwarf planet is nearest the Sun. This suggests the sublimation of surface ices, like a comet, rather than emissions from a hidden ocean.
Then too, sublimation of ice to water vapor should probably been detected from the the supposed frozen lakes, as ice is unstable on the surface of Ceres. There were apparently no such detections.
Further, two substantial impacts would have had to occur very near each other to account for the two bright spots. This is substantially less probable than a single impact.
Impacts that merely exposed subsurface ice, a popular explanation for the bright spots, is not looking so probable, either. The albedo of the bright spots is given as at least 40 percent. Ice on a solid surface, such as glacial ice on Earth has an albedo of 20 to 40 percent. We're told that the bright spots are not yet properly resolved in the current images. They are presumably smaller, and so, brighter than they appear. The resultant albedo of over 40 percent seems to rule out ice resting on the dusty, rocky crust of Ceres.

Ara Pacis
2015-Feb-27, 06:18 PM
Further, two substantial impacts would have had to occur very near each other to account for the two bright spots. This is substantially less probable than a single impact.

Tidal interaction with the impactor might have broken it up if it was a rubble pile. Perhaps more likely, the impactor had a moon. Perhaps less likely, the impactor bounced. As for ice, perhaps it was the impactor that was made of ice.

Zartan
2015-Feb-27, 07:11 PM
Tidal interaction with the impactor might have broken it up if it was a rubble pile. Perhaps more likely, the impactor had a moon. Perhaps less likely, the impactor bounced. As for ice, perhaps it was the impactor that was made of ice.

I don't think an impactor would have left behind large chunk of ice on site?
Looking closely, the crater around Great Bright Spot seems slightly oblated. Maybe it was somewhat oblique impact which for some reason resulted to twin central peak. Then, uh, magic happened and the peaks became very bright? :whistle:
Crater itself around it doesn't really look that much more fresh than some other craters which do not have similar bright features...though obviously, resolution is still very low.

ToSeek
2015-Feb-27, 09:13 PM
It should be obvious that there are 2 possible explanations :

Ceres is hollow and those glowing spots are the rocket exhausts.
or
The sun is glinting off of 2 giant saucers presently on the surface.

Another likely 3rd explanation is that my wife served me decaf this morning.
We should know which one is the correct answer in a few days.

Personally, I'm rooting for a 2001-esque monolith right in the center of one of them.

galacsi
2015-Feb-27, 09:21 PM
It will be really cool to see the close up images in March and April, and see what's going on. Likely its salt, or ice, or something similar as proposed above.

May be this bright spot is not only a double but triple, quadruple etc. Impossible to know before getting better photos.Yes in April I think.

Ara Pacis
2015-Feb-28, 05:56 AM
I don't think an impactor would have left behind large chunk of ice on site?

Lots of little chunks, or powdery.

grapes
2015-Mar-13, 08:24 PM
http://xkcd.com/1476/

publiusr
2015-Mar-14, 08:28 PM
Here goes. A low velocity comet fragment passes very slowly, simulating DAWN's own leisurely approach. This ice moon strikes an older crater, then skids to a halt halfway up the side of the old fast meteor crater. Terminal velocity is lower here after all, and this is still an asteroid more than a planet.

The heat fills in some of the crater with a water table, and the second smaller bright spot is the core itself?

Ross 54
2015-Mar-15, 03:32 PM
I still have to ask myself: How often do comets strike little Ceres? Not a very large or gravitationally attractive target. How long afterward, before ice, which, we're told, is unstable of Ceres surface, sublimes away? And-- how does a frozen lake at the bottom of the 57 mile-wide crater reflect light when it's surrounded by darkness, as appears to be the case in some recent images?

publiusr
2015-Mar-15, 07:42 PM
Being in the asteroid belt itself, I would think impacts would be low velocity. I wonder if any comets came that way recently.

I don't see a lot of rays out of the craters. In some ways, it doesn't really look like the moon--whose craters were once thought to be Maar type eruptions. Pingos have been all the rage

Maybe we are seeing something new to us in terms of crater formation.

fjong1200
2015-Apr-05, 06:34 AM
Could the 2 bright spots on Ceres possible be sodium?, the thought accured to me as i just saw someone mention that some sodium deposits on earth was visible to the astronauts on the moon.

Trebuchet
2015-Apr-05, 03:01 PM
Those were probably sodium chloride deposits -- in other words, salt flats. Metallic sodium doesn't stay that very long. It's extremely chemically active.

fjong1200
2015-Apr-05, 07:45 PM
Yes it was saltflats that they should have been able to spot, im not aware of the difference of metallic sodium and ordinary sodium deposits. in other words i was not assuming that it could be metallic sodium but the same kind found on earth.
So is it possible that the bright spots could be sodium cloride crystals reflecting from those spots?

Swift
2015-Apr-06, 01:38 AM
Could the 2 bright spots on Ceres possible be sodium?, the thought accured to me as i just saw someone mention that some sodium deposits on earth was visible to the astronauts on the moon.
fjong1200

I've merged your thread in Geology with an on-going thread about the bright spots on Ceres in Astronomy. Please continue the discussion here.

Swift
2015-Apr-06, 01:40 AM
Yes it was saltflats that they should have been able to spot, im not aware of the difference of metallic sodium and ordinary sodium deposits. in other words i was not assuming that it could be metallic sodium but the same kind found on earth.
So is it possible that the bright spots could be sodium cloride crystals reflecting from those spots?
I would seem highly unlikely. Salt flats form when salty water evaporates, such as from an ocean. Ceres doesn't even have an atmosphere, so an ocean seems highly unlikely.

fjong1200
2015-Apr-06, 02:17 AM
They are 'high albedo features'... Lakdawalla discusses about them (among other stuff) here (http://www.planetary.org/blogs/emily-lakdawalla/2015/02251857-ceres-geology.html).
They are not necessarily exceptionally bright, just appear that way since Ceres is pretty dark overall. Nevertheless, such a high albedo contrast seems bit unusual. Obvious answer is that it's brighter material excavated by fresh impact, but this is somewhat problematic as they don't look much like bright impact features on other bodies.
With low resolution pictures as we've had so far, high albedo features become oversaturated and may appear much bigger than they really are, compare this old Hubble pic (http://upload.wikimedia.org/wikipedia/commons/3/33/Ceres_Hubble_sing.jpg) for example.

The dark 'Piazzi' feature seen in old HST and Keck images is not really showing up in Dawn images. Guess they'll name the big, flat crater 'Piazzi'...

I read that the albedo are a mere 9% to the surrounding surface, but still almost tarmack black. pretty good contrast work, without over exaggerating the rest of the surface.

fjong1200
2015-Apr-06, 02:25 AM
i was never suggesting a saltflat mechanic! like outwashing of minerals here on earth. Just asking if it could be sodium cloride or simular regardless of the depository factors.
I have no idea if such accumulations are even possible without outwashing, or if mountains of salt could be found naturally here or on other bodies.

Superluminal
2015-Apr-06, 06:51 AM
I would seem highly unlikely. Salt flats form when salty water evaporates, such as from an ocean. Ceres doesn't even have an atmosphere, so an ocean seems highly unlikely.
Could it be salt brought to the surface by out gassing? IIRC, didn't Cassini find salts or something similar erupting from Enceladus?

galacsi
2015-Apr-06, 07:28 AM
Could it be salt brought to the surface by out gassing? IIRC, didn't Cassini find salts or something similar erupting from Enceladus?

Or salt from the salten ocean under the superficial crust .There has been an outpouring , water evaporated in the void and the salt is left on the ground.
I prefer ice , laid bare by a meteorite impact. But it could be both ice and salt.

Ross 54
2015-Apr-06, 03:01 PM
If Ceres once had an underground ocean, it's likely frozen by now. Such a small body as Ceres probably hasn't retained enough internal heat to keep such an ocean liquid. Ceres isn't subject to significant tidal friction. This is where Saturn's moon Enceladus derives most of the internal heat that keeps its subsurface water liquid, and allows it to spout to the surface in the form of geysers.
Small surface deposits of ice seem likely on Ceres, as water vapor has been detected above the planet's surface, when it's nearest the Sun. As these sublimed to vapor they would presumably leave behind any salt they contained.
This salt would presumably be darkened and pitted by meteor and micrometeor impacts. The bright spots on Ceres already seem significantly brighter than examples of disrupted, soiled salt flats found on Earth. The bright spots are optically unresolved, at present. They will presumably be found to be smaller, and so, even brighter than they now appear.

Ross 54
2015-Apr-10, 06:28 PM
According to the published schedule, Dawn should be making images of Ceres today. With past experience as a guide we may hope to see these by the 15th or 16th. Subsequent image-taking is planned for the 14th. These will probably be released by the 19th or 20th.
Current uncertainties about Ceres' period of rotation means that the bright spots may or may not be visible in these images. It will be interesting to see which is the case.

Explorer Ron
2015-Apr-18, 08:58 PM
(BEFORE)-NASA; Ceres's Two Bight Spots Extreme Image Closeups Attained By Texas Scientist

Some images on our front webpage are our slide show. Or if you wish you may also watch the video. You may find our Home page at-

http://www.journals-of-science.com/-ijaar.html

You Tube Video at- http://youtu.be/kFHeTwtzRbo

Thank you!

grapes
2015-Apr-23, 11:05 AM
In latest animation (http://photojournal.jpl.nasa.gov/archive/PIA19064.gif), the spots only 'light up' when they rotate into sunlight so that seems to rule out an active light source.
That animation seems to start with another bright area.

Superluminal
2015-Apr-24, 11:35 PM
When it rotates into view, just for a moment the brightest spot looks as if it is a crater with a very bright rim.

Jerry
2015-Apr-25, 02:44 AM
(BEFORE)-NASA; Ceres's Two Bight Spots Extreme Image Closeups Attained By Texas Scientist

Some images on our front webpage are our slide show. Or if you wish you may also watch the video. You may find our Home page at-

http://www.journals-of-science.com/-ijaar.html

You Tube Video at- http://youtu.be/kFHeTwtzRbo

The website is a color jungle - it makes my head hurt because of the multiple crass fonts chosen; and the Utube video has been removed.