'Bright spot' on Ceres has dimmer companion

February 26, 2015
This image was taken by NASA's Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dwarf planet Ceres continues to puzzle scientists as NASA's Dawn spacecraft gets closer to being captured into orbit around the object. The latest images from Dawn, taken nearly 29,000 miles (46,000 kilometers) from Ceres, reveal that a bright spot that stands out in previous images lies close to yet another bright area.

"Ceres' bright spot can now be seen to have a companion of lesser brightness, but apparently in the same basin. This may be pointing to a volcano-like origin of the spots, but we will have to wait for better resolution before we can make such geologic interpretations," said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.

Using its ion propulsion system, Dawn will enter orbit around Ceres on March 6. As scientists receive better and better views of the dwarf planet over the next 16 months, they hope to gain a deeper understanding of its origin and evolution by studying its surface. The intriguing bright spots and other interesting features of this captivating world will come into sharper focus.

"The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres. This is truly unexpected and still a mystery to us," said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany.

Dawn visited the giant asteroid Vesta from 2011 to 2012, delivering more than 30,000 images of the body along with many other measurements, and providing insights about its composition and geological history. Vesta has an average diameter of 326 miles (525 kilometers), while Ceres has an average diameter of 590 miles (950 kilometers). Vesta and Ceres are the two most massive bodies in the asteroid belt, located between Mars and Jupiter.

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49 comments

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travisr
1 / 5 (4) Feb 26, 2015
This is "Pushing Ice" by Alistair Reynolds
verkle
Feb 26, 2015
This comment has been removed by a moderator.
TechnoCreed
4.4 / 5 (7) Feb 26, 2015
We will get more images (OpNav5) early next week. Meanwhile if you want to see the complete set of images (Opnav4) follow the link, you will also get much more information than on this deceptively frugal article. http://dawnblog.j...uary-25/
cantdrive85
1.4 / 5 (9) Feb 26, 2015
The simplest yet most avoided suggestion is that it is a form of electric discharge. We have observed electric discharge on many of the Solar Systems objects yet it seem devoid from the conversation. What other "dark" entity will be employed to explain away this bright spot.
Solon
5 / 5 (5) Feb 27, 2015
We will get more images (OpNav5) early next week. Meanwhile if you want to see the complete set of images (Opnav4) follow the link, you will also get much more information than on this deceptively frugal article. http://dawnblog.j...uary-25/


Would you happen to know where to find more info for these images, filter and exposure times ? It might help to figure out what is going on if we knew more. I suspect it is detecting IR.
ubavontuba
1 / 5 (5) Feb 27, 2015
No, no, no. You have it all wrong. This is debris from the Roswell crash of '47.

It seems a few alien teenagers were out celebrating their graduation from alien high school and they got a little tipsy (probably on bootleg Romulan Ale) before snatching the old man's keys. Sadly, they forgot to turn on the hazard avoidance system and nicked a big chunk out of the right fender on Ceres, to subsequently come careening onto Earth.

TechnoCreed
5 / 5 (4) Feb 27, 2015
Would you happen to know where to find more info for these images, filter and exposure times ? It might help to figure out what is going on if we knew more. I suspect it is detecting IR.
First science results from Dawn are going to be presented in the middle of march. My guess is that it is going to get public soon after that. http://www.hou.us...psc2015/
Torbjorn_Larsson_OM
5 / 5 (5) Feb 27, 2015
Ceres is darker than the Moon, which itself is darker than charcoal. It would take very little ice around (and in the opening of) a fresh vent to make these spot-on-center-of-old-impacts areas light up. Especially if they have used IR as Solon notes.

Fresh vents could explain the vapor plumes seen earlier. "Astronomers have discovered direct evidence of water on the dwarf planet Ceres in the form of vapor plumes erupting into space, possibly from volcano-like ice geysers on its surface." [ http://www.space....oes.html ]

This could be another, but closer, Enceladus, a subsurface tidal (and solar) heated ocean venting directly to space. I assume Enceladus "E" ring is due the relatively rapid rotation, while Ceres has nearly 5 years to close an orbit. [ http://en.wikiped...lanet%29 ]
Moebius
1 / 5 (1) Feb 27, 2015
I'll bet it mysteriously vanishes.
TechnoCreed
3.7 / 5 (3) Feb 27, 2015
First science results from Dawn...
I meant the Ceres approach phase science results.

@Torbjorn
Ceres is darker than the Moon, which itself is darker than charcoal. It would take very little ice around (and in the opening of) a fresh vent to make these spot-on-center-of-old-impacts areas light up. Especially if they have used IR as Solon notes.
I guess that you did not have your morning coffee when you posted this comment. The moon is not so dark, more like grayish as you can see on the following pictures: http://commons.wi...inal.jpg and do not forget Aldrin's picture is at Mare Tranquillitatis (relatively low reflective area of the moon).

Cont.
TechnoCreed
5 / 5 (3) Feb 27, 2015
...
Moon's albedo is 0.12 Ceres's is 0.09, if you look at the next picture: https://www.flick...2183586/ My opinion is that Ceres has about the same reflectivity than the lunar Mares, so it should be about the same colour as Aldrin's picture but 9X less luminous because it is at 3 AU. As for the IR question, The Dawn camera uses the Thompson TH7888A package that is sealed with a specific anti-reflective window optimized in 400-700 nm spectrum bandwidth. So it is strictly in the visual spectrum. The opening comment was humorous of course; I find your usual comments to be well informed. Also do not take mine as face value I only write from personal knowledge.
barakn
5 / 5 (3) Feb 27, 2015
I guess that you did not have your morning coffee when you posted this comment. The moon is not so dark, more like grayish as you can see on the following pictures: http://commons.wi...inal.jpg and do not forget Aldrin's picture is at Mare Tranquillitatis (relatively low reflective area of the moon).

Cont.
The moon is dark. It can be made to look bright in a photo by increasing the aperture size or increasing the exposure time. If you ever doubt how dim it is, try to find it in the sky after the sun has come up.
TechnoCreed
3.7 / 5 (3) Feb 27, 2015
@barakn
The moon is dark. It can be made to look bright in a photo by increasing the aperture size or increasing the exposure time. If you ever doubt how dim it is, try to find it in the sky after the sun has come up.
It is pretty useless to bring photometry into this. Torbjorn said than the moon was darker than charcoal. I said that it was not. We are talking about what it looks when there is light that shines on it. You are not convinced; you want to see another picture? http://en.wikiped...tory.jpg

Vietvet
4.3 / 5 (6) Feb 27, 2015
The Planetary Society has an article by a geologist about Ceres and other bodies that goes into detail about albedo with great images.

http://www.planet...ogy.html
Solon
5 / 5 (3) Feb 28, 2015
...
... The Dawn camera uses the Thompson TH7888A package that is sealed with a specific anti-reflective window optimized in 400-700 nm spectrum bandwidth. So it is strictly in the visual spectrum.


The graphic on this page shows filters F4,5 and 6 as being in the IR it seems.
http://indico.cer...ribId=19
TechnoCreed
5 / 5 (2) Feb 28, 2015
Astute observation, but this is just a tiny part of the IR spectrum; the "almost visible" half of the near IR band. Those filters (from your paper: around 750nm, 825nm, 900nm, 975nm) correspond to wavelength to "hot" to visualize Ceres's IR radiation spectrum. http://www.wolfra...u---.*--
http://www.wolfra...u---.*-- ,
cont.
TechnoCreed
5 / 5 (2) Feb 28, 2015
...
http://www.wolfra...u---.*-- , http://www.wolfra...u---.*-- ,
For this, you are going to have to wait for the VIR instrument results. http://dawn.artov...vir.html
Landrew
5 / 5 (1) Mar 03, 2015
This story is a very good test of our propensity to cope with unexplained mysteries, or at the very least, our ability to adopt a position of scientific uncertainty. We love to see things as either black or white; and we don't like to be stumped, therefore we feel we must always posit an explanation to every question, no matter how lame or inane it might be.

Scientific uncertainty is unquestionably the best attitude with which to approach such a mystery; certainly better than dismissive-denial or a forced conclusion, unsupported by research.

Apparently there exists a great fear of being negatively-labeled for adopting anything resembling an open mind towards an unorthodox hypothesis for evidence which is unexpectedly unusual or strange. This seems to inspire in some a state of denial, which often leads to such stories being forgotten or buried before they have been thoroughly investigated. Is this what we wish for this story?
barakn
5 / 5 (3) Mar 05, 2015
It is pretty useless to bring photometry into this. Torbjorn said than the moon was darker than charcoal. I said that it was not. We are talking about what it looks when there is light that shines on it. You are not convinced; you want to see another picture? http://en.wikiped...tory.jpg -Technocreed
No, I didn't want to see another picture, at least not one that didn't have samples of charcoal and regolith side by side. Once again, the photographer has complete control over the exposure and certainly would have increased it to capture detail in what is obviously a very dark material. However, I did check up on the albedo of charcoal (.04) vs the visual geometric albedo of the Moon at .12, and charcoal is darker. Torbjorn is wrong, though your pictures did nothing to prove it.
TechnoCreed
5 / 5 (2) Mar 06, 2015
@barakn
You are so lucky that your post did not go unnoticed by me! Just a good timing to notice it on Physorg.

You are a piece of work you know! ;-) Do not take it as an insult, I mean it in a sort of friendly way, as I am going to spend a fair amount of time to properly present what I have previously said. I hope that you are going to follow my posts on this in the next few days. Just click on an appreciation (1 to 5 stars) or post a comment to approve or argue; this way I will know that I am not totally wasting my time.
TechnoCreed
5 / 5 (2) Mar 07, 2015
@barackn
Commenting is one thing, being scientific and building the arguments to properly demonstrate what I said is something else. Since I have committed to do this demonstration, I will do it no matter what. Also, since being scientific means not to speculate, I might very well fail.

This article is almost 10 days old and is not interesting anymore because of frequent updates. One day after my previous post, I have only Vietvet for public, which is good, I like him and would not want to deceive him. At least acknowledge if you do not want to participate, so that I know that you are interested.
TechnoCreed
5 / 5 (2) Mar 07, 2015
The pace at which I am going to post will be slow as I will be very careful of what I say; checking every detail before posting. It is still not guaranteed that it is going to be perfectly clear and accurate. For this I will need the participation of everybody who is interested. If some clarifications are needed or some facts have to be corrected, it would be greatly appreciated if you would point them out; it will allow me to avoid ending up with a wrong or biased conclusion.
TechnoCreed
5 / 5 (2) Mar 07, 2015
It is also imperative for this task that I give the reference for my data or the details of my methods, so we can agree on its validity and follow along; as if I was myself a witness of this demonstration. My first source of data is here http://nssdc.gsfc...act.html
TechnoCreed
5 / 5 (2) Mar 07, 2015
What if I would start by comforting your vision of the Moon? The visual geometric albedo is 0.12. It means that there is 12 percent of the light from the visible spectrum of the sun that hits the moon that is reflected back to us, this in the specific condition that the earth is between the sun and the moon and is at opposition surge. So we can visualise this from a greyscale chart. Ideally it would be viewed from a calibrated chart on a physical cardboard but, if you agree and just to get a common tool, it will be our computer screen.
TechnoCreed
5 / 5 (2) Mar 07, 2015
Here is a greyscale that I have edited to show a 12% reflective surface (the 100 pixels grey square). If you look at the lower part of the chart and visually go from left to right, you see an even progression from totally reflective to totally non-reflective surface in steps of -17 digital levels of an 8 bits (256 possible levels) starting at 255 (100%) and going down: 100%, 93.33%, 86.67%, 80%, 73.33%, 66.67%, 60%, 53.33%, 46.67%, 40%, 37.33%, 26.67%, 20%, 13.33%, 6.67% and 0%. The histogram module tells you that we are at level 31 so it is 31/255 so it is at 12.56% and is the actual measurement of my grey square. Sorry I should have edited at level 30 it would had been closer to 12% but it still give you a general idea. . .
TechnoCreed
5 / 5 (2) Mar 07, 2015
http://i.imgur.com/SdMsz93.jpg
For some reason the link does not appear but if you copy pace the URL it work fine. I guess the editor does not recognise (.jpg)
TechnoCreed
5 / 5 (2) Mar 07, 2015
Then you have the mighty Bond albedo that gives you a mean ratio (from all angles exposed straight to the sun) of the full EM spectrum of the sun. It is the most exact way to know how much radiation the astronomic body reflects from what it absorbs. EM radiation = energy: The Bond albedo of the Moon is 0.11.

The Moon absorbs 89% of the energy it receives from the sun! Ouch it gets pretty hot up there! Well, it is only one hemisphere at a time and since the Moon is very emissive (radiates very well in the IR spectrum) it keeps its mean temperature at equilibrium.
TechnoCreed
5 / 5 (2) Mar 07, 2015
Also, with such poetic articles like this relatively recent one in the prestigious Sky & Telescope http://www.skyand...2312014/ I can very much appreciate why you would not let a quidam shake your certitudes.

With all the evidence that I have presented so far, I am pretty sure that you think that I am in trouble, don't you?
TechnoCreed
5 / 5 (1) Mar 07, 2015
The following parts will not go as painless. That is where I start to deconstruct the view that is so carelessly carried from people to people because it is the 'effortless' answer.
barakn
5 / 5 (2) Mar 24, 2015
The pace at which I am going to post will be slow

Yes, evidently.
With all the evidence that I have presented so far, I am pretty sure that you think that I am in trouble, don't you?
Indeed.
TechnoCreed
not rated yet Apr 16, 2015
The pace at which I am going to post will be slow

Yes, evidently.
With all the evidence that I have presented so far, I am pretty sure that you think that I am in trouble, don't you?
Indeed.

You are a funny guy...

It is alright I like good humour.
TechnoCreed
not rated yet Apr 16, 2015
If you look at the first comment wrote on March 6th ,
Just click on an appreciation (1 to 5 stars) or post a comment to approve or argue; this way I will know that I am not totally wasting my time.
I clearly asked you to, at least, signify your interest.

Since you did not acknowledged, I concluded that you were not interested in this discussion.
TechnoCreed
not rated yet Apr 16, 2015
There is 10 days left before Physorg close the comments on this article. I think it is plenty of time to have a fruitful discussion.
TechnoCreed
5 / 5 (1) Apr 17, 2015
On this, you are almost suggesting that all photos are suspicious and cannot be trusted. I do not agree with that but I admit that I have been a bit fooled by the regolith dust that I linked from Wikipedia. When you take a second look at this picture you notice that the colours are not right; it is kind of sepia. You can compare the colour corrected picture on this link http://i.imgur.com/qMmqBgt.jpg I manually corrected the colours by interpreting the left 'uniformly coloured' surface of the table as pure grey. It must be close to that if you compare it to the bare metal holders and fasteners. The left photo is the original from Wikipedia the one on the right is the one that I have corected.
TechnoCreed
5 / 5 (1) Apr 17, 2015
From this colour corrected picture you can compare the black enclosure with the dark brown regolith. It is not charcoal but it is black and, with this, can have a proper appreciation of this lunar dust. I specify 'this lunar dust' because there is chemical composition variation so colour and aspect contrast variation depending on lunar location it was sampled from.
TechnoCreed
5 / 5 (1) Apr 17, 2015
I will also add that you cannot unwillingly give a false impression of the contrasts by playing with the exposure time when the contrasts are high; meaning when there are dark objects and bright objects in the same photo composition. Like the picture of 'Buzz' Aldrin that I also linked from Wikipedia. Else you lose details in the whites because of saturation caused by overexposure or you lose details in the blacks because of underexposure. In other word: apart from the colour correction needed on the lunar dust sample, it is not possible to give a false impression of the general aspect of the scene on the pictures that I linked.
TechnoCreed
not rated yet Apr 17, 2015
The 3 comments above refers to this comments:

I guess that you did not have your morning coffee when you posted this comment. The moon is not so dark, more like grayish as you can see on the following pictures: http://commons.wi...inal.jpg and do not forget Aldrin's picture is at Mare Tranquillitatis (relatively low reflective area of the moon).
The moon is dark. It can be made to look bright in a photo by increasing the aperture size or increasing the exposure time. If you ever doubt how dim it is, try to find it in the sky after the sun has come up.
posted by barakn on Feb 27.

and to
TechnoCreed
not rated yet Apr 17, 2015
It is pretty useless to bring photometry into this. Torbjorn said than the moon was darker than charcoal. I said that it was not. We are talking about what it looks when there is light that shines on it. You are not convinced; you want to see another picture? http://en.wikiped...tory.jpg -Technocreed
No, I didn't want to see another picture, at least not one that didn't have samples of charcoal and regolith side by side. Once again, the photographer has complete control over the exposure and certainly would have increased it to capture detail in what is obviously a very dark material. However, I did check up on the albedo of charcoal (.04) vs the visual geometric albedo of the Moon at .12, and charcoal is darker. Torbjorn is wrong, though your pictures did nothing to prove it.

also posted by barakn this one on march 05.
TechnoCreed
5 / 5 (1) Apr 25, 2015
@barakn
I have promised it, so here it is; my take on the colour and albedo of the Moon. It took a while, I know, but I hope you will appreciate it just the same... enjoy.
TechnoCreed
5 / 5 (1) Apr 25, 2015
One thing I want to bring forward right at the beginning of this short essay is that indeed the lunar surface can be very black at some place, but it is not everywhere the same. A second point is that there is a difference between a black surface and a dark surface and there again the darkness/whiteness or albedo of its surface is not the same everywhere. A third point is that its moon is not purely grey; although very subtle, there are some colour variations on the Moon dusty surface.
TechnoCreed
5 / 5 (1) Apr 25, 2015
Using charcoal as a reference for the surface aspect of the moon gives a misleading impression and that is why I objected to Torbjorg comment; charcoal is very black and probably that it can describe the colour of the soil at some place there, namely the Appolo 11 landing site, after all Neil Armstrong said so himself https://www.youtu...cdxvNI1o and who am I to say that he was wrong.
TechnoCreed
5 / 5 (1) Apr 25, 2015
But, at the same site, the normal aldedo of the Appolo 11 landing site is very close to 10% http://adsabs.har...58L.129W and that is not the albedo of charcoal which is 4%: The human eye have a hard time to characterize the difference between those two relatively close contrasts without a chart (Here is one in steps of 3.137%. http://www.w3scho...lors.asp Could you tell the difference between the 2nd and 4th level?).
TechnoCreed
5 / 5 (1) Apr 25, 2015
One thing that has to be discussed when talking about the albedo and the reflective quality of the surface of the moon is the non-negligible specular component http://en.wikiped...flection ; the lunar dust has a lot of glassy beads and glassy agglutinates that can shine light right back at you just like a reflector. This specular component makes it difficult, I agree, to make a proper assessment of the real 'grayness' but BDRF http://en.wikiped...function makes it possible to factor out this component. So when you see the expression 'normal albedo' for a specific location, you can literally look at a gray chart and have the correct 'grayness' of this location.
TechnoCreed
5 / 5 (1) Apr 25, 2015
A word on perceptible colour variation on the Moon. Although it is possible to highlight some colours with the use of filters, http://lroc.sese....osts/223 the soil is mostly perceptible in shades of red. This is very obvious when you look at those lunar soil characterization soil characterisation reflectance graphs http://www.planet...oil.html (Reflectance and albedo is two very different things do not get confused). The chart that starts with number 10 are from Appolo 11, those who starts with number 12, 14 and 15 are from Appolo 12, 14 and 16 respectively, finally those who starts with the number 6 and 7, from Appolo 16 and 17.
TechnoCreed
5 / 5 (1) Apr 25, 2015
On those charts look at the blue line; it describes the reflectance of bulk soil. On all the charts the red 700 nanometer is much more reflective than the blue 400 nanometer. In other word, if you would be there, it would generally look kind of brownish. This concurs with Armstrong's description from an earlier link, it concurs with this paper http://link.sprin...00589167 that measured the normal albedo of the moon at different wavelength (Just the two first page available is sufficient) and also concurs with the colour temperature of the sunlight reflected from the Moon. The colour temperature of the sunlight is 5900k, the colour of the moonlight is around 4100k; http://en.wikiped...perature if the Moon would be neutral... if it would be gray the colour temperature of the reflected light would not change.
TechnoCreed
5 / 5 (1) Apr 25, 2015
A word on the 'geometric albedo' of the Moon. This expression means 'albedo as seen from the earth' we measure the albedo of the full Moon from the Earth at the problematic 0 degree phase angle. Why is it problematic? Because at when we get close to it, there is a phenomenon known as 'opposition surge' http://en.wikiped...on_surge that you have to factor out. To do that you have to measure the light reflected from the Moon at many phases to determine the specular component to factor out. It is also problematic because at 0 degree phase angle the Moon is in the shadow of the Earth.
TechnoCreed
5 / 5 (1) Apr 25, 2015
What I want to emphasize is that the geometric albedo is not a straight forward measurement it is also somewhat of a mathematical entity. Wikipedia has explain quite well what the geometric albedo http://en.wikiped...c_albedo is but does not mention that it is measured using the Johnson V band filter; http://en.wikiped...c_system it is where the human visual sensitivity is at its peak (forget the whole visual spectrum).
TechnoCreed
5 / 5 (1) Apr 25, 2015
If you look at the geometric albedo of a body illuminated by the sun cannot be more than 67% (see the albedo of the very reflective planet Venus). With a geometric albedo of Enceladus 1.4 is a very special case: It is not more reflective than Venus, but receives and shines back more light from Saturn and its ring than from the sun directly.
TechnoCreed
5 / 5 (1) Apr 25, 2015
So what is behind this 67% geometric albedo for Venus when we know that it shines almost 100% of the light it receives? Second line of the Wikipedia link 'an idealized flat, fully reflecting diffusely scattering (Lambertian) disk with the same cross-section'. The Moon is not a disk, it is a sphere but the geometric albedo only account for the lights that shines ahead, like a disk; it discount what is called the 'phase integral' http://en.wikiped...integral which is 1/3 of the light. The Moon has a geometric albedo of 12% + the phase integral 6% the Moon shines 18% of the green light as perceived from the Johnson V band spectrum. This is not so gray after all; look at the last gray chart at the rgb(48,48,48) level. http://www.w3scho...lors.asp

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