APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

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APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by APOD Robot » Wed Feb 18, 2015 5:08 am

Image Dark Craters and Bright Spots Revealed on Asteroid Ceres

Explanation: What are those bright spots on asteroid Ceres? As the robotic spacecraft Dawn approaches the largest asteroid in the asteroid belt, the puzzle only deepens. Sharper new images taken last week and released yesterday indicate, as expected, that most of the surface of dwarf planet Ceres is dark and heavily cratered like our Moon and the planet Mercury. The new images do not clearly indicate, however, the nature of comparatively bright spots -- although more of them are seen to exist. The enigmatic spots were first noticed on Texas-sized Ceres a few weeks ago during Dawn's approach. The intriguing mystery might well be solved quickly as Dawn continues to advance toward Ceres, being on schedule to enter orbit on March 6.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by ta152h0 » Wed Feb 18, 2015 5:17 am

can I still vote for recent collisions as reason for the white spots ? or not !
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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by bystander » Wed Feb 18, 2015 5:20 am

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Zaphod B » Wed Feb 18, 2015 5:26 am

Am I allowed to vote for paintball hits? :D

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Ann » Wed Feb 18, 2015 5:28 am

Well... the white spots on Ceres just might be similar in nature to the white spots on Callisto.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Chris Peterson » Wed Feb 18, 2015 5:59 am

The problem is we don't really have any processing details. It looks to me like the contrast has been stretched so that the entire intensity space is filled. But Ceres has an albedo of less than 10%. It's as dark as coal. If you take a picture of a lump of coal and stretch the intensity to fill the full space, it will have white spots on it, as well.

Just how white are these areas? Are they 10% brighter than the dark areas, or 1000% brighter? I'd love to see an unprocessed frame. Some information on the actual intensities. I guess that might have to wait until somebody publishes a paper.
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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by alter-ego » Wed Feb 18, 2015 6:16 am

Chris Peterson wrote:Just how white are these areas? Are they 10% brighter than the dark areas, or 1000% brighter? I'd love to see an unprocessed frame. Some information on the actual intensities. I guess that might have to wait until somebody publishes a paper.
The mystery link: http://space.io9.com/just-what-are-thos ... 1684160250 claims the spots are 9% brighter than the surrounding areas.
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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Chris Peterson » Wed Feb 18, 2015 6:23 am

alter-ego wrote:
Chris Peterson wrote:Just how white are these areas? Are they 10% brighter than the dark areas, or 1000% brighter? I'd love to see an unprocessed frame. Some information on the actual intensities. I guess that might have to wait until somebody publishes a paper.
The mystery link: http://space.io9.com/just-what-are-thos ... 1684160250 claims the spots are 9% brighter than the surrounding areas.
So this thing actually does have about the same variation in brightness, or perhaps a little less, as your average lump of coal. We're looking at space weathered rock with some areas that are very slightly less weathered. Say, something with a surface that varies between 10% and 11% reflectivity.
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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by JLGordon10 » Wed Feb 18, 2015 7:46 am

I believe the subsurface of Ceres could be water ice; therefore larger impact craters could expose this lighter, ice dominated layer.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by BobStein-VisiBone » Wed Feb 18, 2015 9:17 am

How about water-ice deposits from colliding comets? So instead of a dirty snowball, it's a snowy dirtball.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by HVM » Wed Feb 18, 2015 9:24 am

A couple of guesses:

1) As pointed out by others, the while spots could be the lighter sub surface soil OR ice uncovered by meteorite collisions
2) Erosion of the surface caused by solar wind. Based on the constituents of the surface, the interaction with the solar wind may have 'whitened' some of the regions now seen as while spots.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Ann » Wed Feb 18, 2015 10:27 am

Chris Peterson wrote:
alter-ego wrote:
Chris Peterson wrote:Just how white are these areas? Are they 10% brighter than the dark areas, or 1000% brighter? I'd love to see an unprocessed frame. Some information on the actual intensities. I guess that might have to wait until somebody publishes a paper.
The mystery link: http://space.io9.com/just-what-are-thos ... 1684160250 claims the spots are 9% brighter than the surrounding areas.
So this thing actually does have about the same variation in brightness, or perhaps a little less, as your average lump of coal. We're looking at space weathered rock with some areas that are very slightly less weathered. Say, something with a surface that varies between 10% and 11% reflectivity.
Hmm. I googled "lump of coal" and found this picture of a lump of coal with a red ribbon around it.

You are right, Chris, ordinary lumps of coal do show bright highlights.

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Ghociumn

Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Ghociumn » Wed Feb 18, 2015 11:04 am

Try light reflecting off the sides of or out of craters.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by CQN3ARU2 » Wed Feb 18, 2015 11:23 am

Retro reflective fine crystals might produce the bright spots.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by pp18342 » Wed Feb 18, 2015 11:46 am

The universe is an unmeasurable, vast, unexplored and undiscovered place of time and space and you must look at it with an open mind and don't be afraid to speculate and wonder because that is how ideas become reality. My personal opinion is that they are mineing sites of ET's, there is a wealth of anything and every thing out there free for the taking, you just have to find it and dig it up. We do not yet have the means of doing so but I am willing to bet there are others who do!

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Fred Stargazer1 » Wed Feb 18, 2015 12:38 pm

The subsurface is an Iceball, covered by a thin coating of cosmic dust, the white spots are recent Meteor impacts exposing the ice underneath. No telling what is in the center at this time. I think that the "Dirty Snowball" theory applies here.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by rstevenson » Wed Feb 18, 2015 12:51 pm

pp18342 wrote:... don't be afraid to speculate and wonder because that is how ideas become reality. ...
Not quite. Reality exists whether or not you have ideas about it. But having those ideas is a good starting point for finding out about the universe, so long as you use an ordered and productive method of exploration to proceed from your ideas. Humans have spent a very long time developing just such a system of exploration. It's called the scientific method. Ideas are good; science is gooder. :mrgreen:

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Beyond » Wed Feb 18, 2015 1:57 pm

rstevenson wrote:
pp18342 wrote:... don't be afraid to speculate and wonder because that is how ideas become reality. ...
Not quite. Reality exists whether or not you have ideas about it. But having those ideas is a good starting point for finding out about the universe, so long as you use an ordered and productive method of exploration to proceed from your ideas. Humans have spent a very long time developing just such a system of exploration. It's called the scientific method. Ideas are good; science is gooder. :mrgreen:

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Phiphreak » Wed Feb 18, 2015 2:38 pm

If by frozen lakes, you mean the remnants of impact by bodies composed mainly of ice, that would be my vote. The gravity of Ceres would be minimal and the impact velocity of icy bodies would not beenough to vaporize them.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by BMAONE23 » Wed Feb 18, 2015 2:45 pm


Hmm. I googled "lump of coal" and found this picture of a lump of coal with a red ribbon around it.

You are right, Chris, ordinary lumps of coal do show bright highlights.

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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by Ron-Astro Pharmacist » Wed Feb 18, 2015 5:35 pm

Considering Cere's low albedo it's a little hard to see that the craters are darker than an average crater. Is the title of today's APOD misleading or are they really dark?

I'd say this crater is dark.
North_pole_of_Mercury_--_NASA.jpg
But maybe it's just a case of the : spacial Ceres of relative crater darkness? :D
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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by tmulcahy » Wed Feb 18, 2015 9:38 pm

Reflection of light on crushed crystalline rock mixed with soil, possibly the result of the impact of a crystalline meteor, or of a meteor on a crystalline deposit. I suspect the brightness may disappear on closer examination, and that only on-site examination of the soil in those areas will reveal the explanation.
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Re: Texas size me

Post by BDanielMayfield » Thu Feb 19, 2015 12:36 am

APOD Robot wrote:... dwarf planet Ceres ... Texas-sized Ceres ...
Ahem, something called a DWARF is called Texas-sized??? :ssmile:

Sticking to metric units favored by the scientifically inclined, the Wikipedia link on Ceres shows that it has a mean radius of 476 km, so it's diameter is about 952 km. TEXAS, on the other hand is 1,244 km wide (East-West) x 1,270 km (North-South).


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Re: APOD: Dark Craters and Bright Spots on... (2015 Feb 18)

Post by mz* » Thu Feb 19, 2015 12:48 am

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Re: Texas size me

Post by Nitpicker » Thu Feb 19, 2015 1:29 am

BDanielMayfield wrote:
APOD Robot wrote:... dwarf planet Ceres ... Texas-sized Ceres ...
Ahem, something called a DWARF is called Texas-sized??? :ssmile:

Sticking to metric units favored by the scientifically inclined, the Wikipedia link on Ceres shows that it has a mean radius of 476 km, so it's diameter is about 952 km. TEXAS, on the other hand is 1,244 km wide (East-West) x 1,270 km (North-South).


Bruce, a 196 cm tall Texan.
The surface area of Ceres is four times that of Texas. And if the area of Texas were reshaped into a circle, it would have a radius of 471 km.