APOD: MESSENGER's Degas View (2011 Jun 22)

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APOD: MESSENGER's Degas View (2011 Jun 22)

Post by APOD Robot » Wed Jun 22, 2011 4:10 am

Image MESSENGER's Degas View

Explanation: Now imaging inner planet Mercury from orbit, the MESSENGER spacecraft wide angle camera has returned this impressive color view of Degas Crater, with a full resolution of 90 meters per pixel. Named for the impressionist painter, the 52 kilometer diameter crater is also shown in an inset context image from the Mariner 10 flyby mission in the mid 1970s. In MESSENGER's view, the crater floor is seen to be filled with an intricate series of cracks, formed as the molten surface resulting from the impact cooled and contracted. Starkly bright, patchy deposits, suggesting compositional differences and freshly exposed material, standout around the crater's central peaks and walls. Details of similar bright deposits are seen in even higher resolution images from MESSENGER.

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Re: APOD: MESSENGER s Degas View (2011 Jun 22)

Post by Beyond » Wed Jun 22, 2011 4:21 am

Well, it does resemble a giant pizza that's been in the oven tooo long. Understandable given as to how close to the sun it is. I was a bit surprised at how brown the brown is in contrast to the other shades of things and compared to the rest of the 'naked' bodies in our solar system. Seems to me to be rather unusual, given the fact that it is so close to the sun.
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Re: APOD: MESSENGER s Degas View (2011 Jun 22)

Post by Chris Peterson » Wed Jun 22, 2011 4:28 am

Beyond wrote:Well, it does resemble a giant pizza that's been in the oven tooo long. Understandable given as to how close to the sun it is. I was a bit surprised at how brown the brown is in contrast to the other shades of things and compared to the rest of the 'naked' bodies in our solar system. Seems to me to be rather unusual, given the fact that it is so close to the sun.
What are you talking about? There are many shades- ocher, yellow, blue, and others. Wait... it's that "tinge" thing again, isn't it? Shades of gray, and all that? <g>
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by Ann » Wed Jun 22, 2011 10:00 am

Is it or isn't it possible that Mercury may have minerals on its surface whose color might be, say, 50% red, 50% green, and 60% blue? To me, that would constitute a bluish material. Do such materials exist on Mercury?

As I walk on sandy beaches in southern Sweden where I live, I get the impression that the only bluish pebbles or grains of sand that I can find are bits of limestone and blue shell mussels. Perhaps the limestone is bluish because of the blue shell mussels that went into making the limestone?

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by davidgin50 » Wed Jun 22, 2011 11:12 am

Why Degas? It doesn't look remotely like any work of his I have ever seen. If you look at the original B&W photo from Mariner 10 I think "Jackson Pollock Crater" might have been more apt!

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by rstevenson » Wed Jun 22, 2011 12:03 pm

Ann wrote:Is it or isn't it possible that Mercury may have minerals on its surface whose color might be, say, 50% red, 50% green, and 60% blue? To me, that would constitute a bluish material. Do such materials exist on Mercury?
Nah, the closest I can see is about 20/25/27 in %RGB, which can most charitably be described as a dark gray with a tinge of blueish-green.

The image seems to be (from its EXIF data) simple RGB. I couldn't find any indication of the filters that may have been used to take it, or the processing employed since.

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by moikey@att.net » Wed Jun 22, 2011 12:28 pm

Might those be volcanic structures in the center of the large crater?

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by neufer » Wed Jun 22, 2011 12:52 pm

davidgin50 wrote:
Why Degas? It doesn't look remotely like any work of his I have ever seen.
If you look at the original B&W photo from Mariner 10 I think "Jackson Pollock Crater" might have been more apt!
It's really more of a cross between Degas & Busby Berkeley:
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Re: APOD: MESSENGER s Degas View (2011 Jun 22)

Post by Beyond » Wed Jun 22, 2011 2:03 pm

Chris Peterson wrote:
Beyond wrote:Well, it does resemble a giant pizza that's been in the oven tooo long. Understandable given as to how close to the sun it is. I was a bit surprised at how brown the brown is in contrast to the other shades of things and compared to the rest of the 'naked' bodies in our solar system. Seems to me to be rather unusual, given the fact that it is so close to the sun.
What are you talking about? There are many shades- ocher, yellow, blue, and others. Wait... it's that "tinge" thing again, isn't it? Shades of gray, and all that? <g>
Just goes to show that even when individuals are seeing the same thing, it can look a little different to each individual, as each individual sees things a little differently.That's just the way it is. I suppose that if we all saw things the same way, everything would be rather boring.So Viva la differences :!:
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by Chris Peterson » Wed Jun 22, 2011 3:10 pm

rstevenson wrote:The image seems to be (from its EXIF data) simple RGB. I couldn't find any indication of the filters that may have been used to take it, or the processing employed since.
The MESSENGER WAC camera only has narrowband filters, which means producing "true" color images is challenging. I looks like the initial color images were released using R=1000nm, G=750nm, B=430nm, which isn't going to enable the production of accurate color regardless of processing. They have a method of combining data from more than three filters to produce color, and that could in principle give something like "true" color. But assuming this image was made in the same way as similarly appearing images released at the same time (that is, with the above filters), what we are seeing is more of a blue-near IR hybrid mapped into an RGB color space.
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by orin stepanek » Wed Jun 22, 2011 3:30 pm

Of Interest: This WAC image provides an extraordinary view of the crater Degas (pronounced duh-GAH), named for the French Impressionistic artist Edgar Degas. The crater's floor contains cracks that formed as the pool of impact melt cooled and shrank. The high-reflectance material on the walls and in the central portion of the crater probably has a composition distinct from that of the crater floor and surroundings. The illumination conditions and down-slope movement of eroded material exposing fresh rock also contribute to the bright appearance. A color image of part of Degas was featured in the June 16, 2011 NASA MESSENGER press conference.
The high reflective material. Is that what looks white? Looks almost like ice and snow on the picture. :? 'Tis a nice picture of the crater though. 8-)
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by Indigo_Sunrise » Wed Jun 22, 2011 3:53 pm

Orin, I thought it looked like snow, too. For me, it seemed to add a sense of depth/relief.

Nice image!
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by Ann » Wed Jun 22, 2011 7:12 pm

Chris Peterson wrote:
rstevenson wrote:The image seems to be (from its EXIF data) simple RGB. I couldn't find any indication of the filters that may have been used to take it, or the processing employed since.
The MESSENGER WAC camera only has narrowband filters, which means producing "true" color images is challenging. I looks like the initial color images were released using R=1000nm, G=750nm, B=430nm, which isn't going to enable the production of accurate color regardless of processing. They have a method of combining data from more than three filters to produce color, and that could in principle give something like "true" color. But assuming this image was made in the same way as similarly appearing images released at the same time (that is, with the above filters), what we are seeing is more of a blue-near IR hybrid mapped into an RGB color space.
That explains it. I didn't think the colors looked realistic. In particular, I thought that some areas around the Degas crater, particularly the cracks inside it, looked really strangely bluish. I have personally never seen a largish patch of rock here on the Earth look as blue as that, and I can't remember even seeing what appears to be a non-enhanced RGB color photo of another planet showing a sizable patch of ground that looks as blue as that.

Do any known rocky bodies of our solar system have largish patches of ground that are "more B than R and G"?

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by bystander » Wed Jun 22, 2011 7:37 pm

Ann wrote:Do any known rocky bodies of our solar system have largish patches of ground that are "more B than R and G"?
Image
Color enhanced view of the Moon

This is the Moon's true colors! If our eyes were able to detect the subtle color differences, this is what we would see.

The colors are due to different chemical makeup of the moon's crust. Specifically, lavas low in Titanium (TiO2) are red, while lavas with high TiO2 content are blue.

Copyright: SOCIETAS CORONAE BOREALIS - Jan Sonnvik

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by islader2 » Thu Jun 23, 2011 1:27 am

davidgin50: the name of a feature on Mercury or any other body is to meant to honor famous people from a list kept by the Univ Astro Union. A specific name allows us to identify a particular feature by its given (which should unique) name and help wiki provide disambiguation. Thanx.

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by Ann » Thu Jun 23, 2011 7:07 am

bystander wrote:
Ann wrote:Do any known rocky bodies of our solar system have largish patches of ground that are "more B than R and G"?
Image
Color enhanced view of the Moon

This is the Moon's true colors! If our eyes were able to detect the subtle color differences, this is what we would see.

The colors are due to different chemical makeup of the moon's crust. Specifically, lavas low in Titanium (TiO2) are red, while lavas with high TiO2 content are blue.

Copyright: SOCIETAS CORONAE BOREALIS - Jan Sonnvik

Click on image for a bigger version.
Thanks, bystander! I have, of course, seen such color photos of the Moon before, but I have never really taken them absolutely seriously. And why? For two reasons. First, it is obvious that the overall color of the Moon is a dark grayish-brown, which is to say that the Moon is clearly "more R than B", so to speak. This is a famous "Earth and Moon" picture by NASA, where the Moon really looks very brownish:
So the overall color of the Moon is a dark grayish-brown. I think there can be little doubt about that. To me, this suggests that the parts of the Moon that look blue in enhanced color pictures might be a "relative blue", that is, they may be considerably bluer than their surroundings, even though they may still not be "an absolute blue", so that a calibrated monitor would find that they reflect blue light more efficiently than red or green.

Of course I'm just guessing. I don't know if the "blue of the Moon" is an absolute or a relative blue.

Another thing that I find noteworthy is that most of the "blue areas" of the Moon seem to correspond to dark terrain on the Moon. Compare the image below with bystander's color picture:
Photo: Hana Sarova.

There are exceptions to the rule that "blue areas" always seem to be dark. Some bright craters seem to correspond to bluer colors. That is exactly what I would have expected, because I am under the impression that freshly exposed terrain tend to be bluer than old terrain on rocky solar system bodies with thin or negligible atmospheres. That is because the ultraviolet radiation from the Sun darkens and reddens unprotected rocky or icy surfaces in the solar system, or so I believe anyway. If that is true, then new craters would tend to be bluish, although this blue color would normally be a "relative blue" rather than an "absolute blue".

Here is another NASA image of the Earth and the Moon, which is so large that I will only post it as a link. Here you can see the muted grayish-brown overall color of the Moon. You can also see that the parts of the Moon which look blue in the enhanced color image don't look blue here. But you may note a few small bright craters, which do seem to show a faintly bluish tinge:
http://upload.wikimedia.org/wikipedia/c ... d_Moon.jpg

So I'm still not absolutely convinced that the Moon contains largish areas that are an "absolute blue", however faint that blue would be. I agree that an RGB color of 0%, 0% and 1% would indeed constitute an "absolute blue", even though that shade of blue would be indistinguishable from black to human eyes.

Ann

P.S. Here is Phobos, the largest Moon or Mars, with a prominent "pseudo-blue" patch. This part of Phobos isn't really blue, only much less red than the rest of Phobos.
Phobos by Mars Express.
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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by DavidLeodis » Thu Jun 23, 2011 10:40 am

The Mariner 10 mision is mentioned in the explanation. In information about the mission that I found in Wikipedia (dated June 20 2011) I was surprised to read the following:-

"With its maneuvering gas just about exhausted, Mariner 10 started another orbit of the Sun. Engineering tests were continued until March 24, 1975, when final depletion of the nitrogen supply was signaled by the onset of an un-programmed pitch turn. Commands were sent immediately to the spacecraft to turn off its transmitter, and radio signals to Earth ceased.

Mariner 10 is still orbiting the Sun, although its electronics have probably been damaged by the Sun's radiation. Dave Williams of NASA's National Space Science Data Center said in 2005: "[Mariner 10] has not been tracked or spotted from Earth since it stopped transmitting. We can only assume it's still orbiting [The Sun], but the only way it would not be orbiting would be if it had been hit by an asteroid or gravitationally perturbed by a close encounter with a large body, the odds of that happening are extremely small so it is assumed to still be in orbit."

The poor thing must be very hot, but a survivor if it is still orbiting in 2011. :)

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by neufer » Thu Jun 23, 2011 11:17 am

DavidLeodis wrote:
Mariner 10 is still orbiting the Sun, although its electronics have probably been damaged by the Sun's radiation. Dave Williams of NASA's National Space Science Data Center said in 2005: "[Mariner 10] has not been tracked or spotted from Earth since it stopped transmitting. We can only assume it's still orbiting [The Sun], but the only way it would not be orbiting would be if it had been hit by an asteroid or gravitationally perturbed by a close encounter with a large body, the odds of that happening are extremely small so it is assumed to still be in orbit."

The poor thing must be very hot, but a survivor if it is still orbiting in 2011. :)

  • The sun now rose upon the right:
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    Still hid in mist, and on the left
    Went down into the sea.

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by DavidLeodis » Thu Jun 23, 2011 11:25 am

Nice one neufer. :)

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by nguarni » Mon Jul 18, 2011 5:30 pm

Aw c'mon...we earth dwellers know what the white deposits are. Look at an aerial view of any object in a large city that's been there for a while....it's pigeon poop!

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Re: APOD: MESSENGER's Degas View (2011 Jun 22)

Post by neufer » Mon Jul 18, 2011 6:33 pm

Image
Hendrick Goltzius view: Mercury, with his symbols
nguarni wrote:
Aw c'mon...we earth dwellers know what the white deposits are.
Look at an aerial view of any object in a large city that's been there for a while....it's pigeon poop!
Close....

<<Mercury was often accompanied by a cockerel (i.e., a rooster), herald of the new day, a ram or goat, symbolizing fertility, and a tortoise, referring to Mercury's invention of the lyre from a tortoise shell.>>

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