In regards the CWS, I disagree strongly with the analysis made in the press conference that there is no elevation feature associated with it. It strongly appears to me that it is either a structure that makes up a central peak unit, or an impact on an existing central peak unit. The way it dims as its host crater goes into the terminator, but stays visible while the crater floor around it is in shadow, is almost definite in it reaching higher than the shadowed far crater rim.

I really don't buy that this is some odd kind of processing artifact. It shouldn't appear at all when the crater floor is in shadow, if it's a reflection feature, unless it stands up well above the crater floor.

-the other Doug

True. But fabrics are not judged by a physics definition of black bodies. A "black" fabric is simply relatively non-reflective, but under the right kind of lighting, and with the right kind of fabric (especially any kind with a soft or "roughened" surface, like velvet), it can reflect ambient light in such a way as to appear brownish, or reddish, or even bluish.

Under the Wikipedia definition, there really are no "black" fabrics or materials of any kind in our everyday life. Shine a bright light on any "black" item in your house, and you'll see.

-the other Doug

From what I have read, the dark trim on the dress is actually black and the ambient lighting provides the gold tint via surface reflection. So, even with image manipulation, you still get colors that aren't actually inherent in the subject. Interesting!

-the other Doug

And, what you just postulated perfectly describes the formation of the dust and gas tails (the gas and small grains that achieve escape velocity) and the coma (the material that hovers around the nucleus and eventually falls back).

So, working it from the nucleus end, as you just did, results in what we see from a distance in the coma and tails. Good work!

-the other Doug

I seriously doubt that the CWS or the other bright spots we see are from iron asteroids crashing into Ceres. For one thing, especially in the case of the CWS, the primary white spot seems coincident with the central peak structure of a large crater. The impactor that made that crater would have been completely vaporized, and the vapor ejected far and wide, not concentrated in the center of the crater; the size of the crater makes it impossible for it to have been made by a low-velocity impact.

I admit that there could have been a smaller, lower-velocity impact that coincidentally struck the central peak of an older crater. But something tells me that we're looking at some kind of phenomenon related to the morphology of the central peak of the crater within which the CWS dwells. In addition, I will point out that Ceres has been observed to have periodic emissions of water vapor, suggesting geysers or other types of plumes. This is the kind of thing I'd expect to see from small, locally active cryovolcanos, with limited fields of fresh snowfall (so to speak) deposited around the plume sources.

We're obviously still way too far out to see any evidence one way or another, and the most likely scenario is probably that we're seeing fresh impacts which have exhumed fresh, bright ice surfaces that haven't had a chance to weather yet. But I like the idea of the fresh fields of snow surrounding cryovolcano vents, and I wouldn't count them out yet.

-the other Doug

I recall that there were several predictions of a "soft" surface due to high enough temperatures that the ice crust should be, to a certain extent, elastic -- certainly more elastic than a fully rocky crust.

I think we're beginning to see that. A lot of the larger, basin-sized features look like their floors have either been almost fully filled in or -- as would have been predicted by the elastic crust theory -- have completed an isostatic rebound and have re-conformed to a spherical surface. That would be a possible indicator of the ages of large crater events; older craters have rebounded more than newer ones.

Perhaps one of the secondary aspects of this kind of rebound would be the movement of fresh "soft" ice beneath the cratering event, which would result in a slow extrusion of brighter ices through weak points, like central peak formations. Hence the bright spots seen, in some places, near the centers of large craters. Including the CWS.

I've seen a lot of what look to be examples of the "rebounded-floor" craters and basins thus far, especially on the most recent images. I'm looking forward to seeing more and better examples as we get closer and closer...

There is a small, non-embedded stone at the bottom of the linked image that shows one side of white, as well. Sure looks like a piece of whatever broke off the main rock.

-the other Doug

Yeah. I can almost imagine I'm seeing a series of splashes from a big basin impact. But there seem to be very clear boundaries between different strata of the ejecta.

-the other Doug

Looking at Ian's provocatively HST-colored images, I notice a couple of things.

On each image, I have (very crudely, and in this case, I mean crudely) outlined some obvious linear features. The rather powerful impression I get, heightened by the color changes, is that the linear features are the edges of rather extensive mesa units -- or at least, large areas of outer crust that appear to overly the level of the adjacent, lower terrain. I see other examples of this elsewhere, but these are the closest to the terminator and stand out the best.

The right image is very interesting. Now, I know there is a lot of artifacting in these images due to their enlargement. And I know what that can do to an angled line. But the right-hand edge of the linear feature in the right image looks almost scalloped. Almost like the ridge is made up of the longest durned crater chain I ever did see. In support of the crater chain interpretation, the individual scallops don't appear to be all the exact same size, and have (albeit subtle) differences that make them look like actual depressions/scallops, not just image artifacts. I say that with full understanding that the mind can put together blurry images and see things that aren't really there.

In any event, there are obviously some very, very interesting linear features that seem, at this resolution, to be boundaries between different landforms, some of which appear to be higher than/overlying other terrain.

This is going to be one interesting exploration!

-the other Doug

No -- very, very well overlain. The color really stands out as associated with features we're just now beginning to see.

-the other Doug

I'd imagine that would depend on the size and mass of the lump, its velocity and where on the spacecraft it hits Rosetta. Also, a lump or clump could hit in a bad spot -- on the outer lensing of OSIRIS, say -- and leave enough material to degrade the imaging.

Fingers and toes crossed, nothing terribly untoward will happen. But I gotta think the mission planners knew they'd be running such risks when they planned extended operations inside the coma of an active comet.

Hey, guys -- as with Sherbert, I was just giving my impression of what we're seeing from the distant images. Ceres does look lumpier than I expected from this distance, and I'm not the first here who has made that observation. Obviously, as distance decreases, we will know more and more of the truth of the matter. And also, as has been stated here, if we couldn't speculate at this point, it wouldn't be any fun...

As for Enceladus, I was looking with tired eyes, I guess -- and relying on Wikipedia being consistent in how it presents information, which is always dangerous. Before I wrote that, last night, I checked and Wikipedia said that each was about 500 km wide -- except that, upon a further look this morning, it was giving a diameter of Enceladus and a radius of Ceres. And, stupid me, I read them as being the same measurement. But, ultimately, my bad.

-the other Doug

What I guess I would have expected of a dwarf planet to look like would be, um, well -- a little more well-rounded. The overall impression I get from the opnavs is of a lumpy body that is out-of-round in significant places.

It doesn't give the same impression of smooth roundness that, say, Enceladus does (as a body of very similar size). I suppose I was expecting something a little more like that. Instead, it seems to have corners and gouges and big uplifted sections and long connected depressions. Complex and fascinating, but less overall rounded than I expected.

Statistically, if other cratered bodies are anything to go by, there should not be a dichotomy in terms of what portions of Ceres were hit by large impactors and what portions were not. I think one thing that is fooling us right now is that the lower half of the disk we see is at a lower sun angle, and thus shows more relief. The northern half may be nearly as heavily cratered as the southern, just washed out due to more overhead lighting in these images.

Also, a lot of the "smoother" terrain, even in the southern portion of the images, looks a little to me like basin floors, which may well end up smoothing themselves out more than ringwalls thrown up by large impacts.

It's tremendously exciting to know the resolution will improve an awful lot over the next week or two!

-the other Doug

It may just be a function of the viewing angle, but, in the February 3 image, for all the world it looks like there are jets coming off of the near lobe of the comet pointed almost directly away from the camera, flowing parallel to the neck and then striking and flowing off of the far lobe. I can understand the striations on the underside of the neck leading up into to the far lobe, if that's what's happening -- they're the result of "wind" erosion.

-the other Doug

I've been looking for any sign of rays from the White Spot, and on the latest opnavs, I do believe I see some.

There is a fan of higher-albedo terrain splayed out over an arc of a good 30 to 40 degrees, from almost directly west to west-northwest from the spot. It's subtle in the latest opnavs, but I am convinced it's there.

Looking in the other direction, to the east and especially northeast, you see the dark terrain, but again in the latest imagery I begin to see something of a wedge-shaped structure to it as it comes out of the spot.

So, while I'm not saying anything definitively, I would not at all be surprised to see, when we get closer, a big ol' crater, very much brighter than its surroundings, with light-toned ejecta to the northwest and dark-toned ejecta to the east and northeast. If so, that thing is going to be very, very impressive to look at.

-the other Doug

One thing I'll note -- the craters we're seeing up here on the upper slopes of Tribulation look like they have regular rock ejecta. The craters down on the plains, and in the lower units, had that quick-eroding evaporite that would crack and make the entire crater, rim and ejecta and all, look like it was put together from mosaic pieces. You don't see that in and around the craters up here.

It'll be interesting to see when the craters resume that mosaiced appearance.

-the other Doug

Well, there are some very definite signs of LHB-style cratering around the southern polar region, where we get a lower sun angle and shadows are more pronounced. This sure leads the eye to perceive the mottling evident at higher sun angles as cratering, as well. I can convince myself that I see a huge basin about a quarter of the way around the planet, to the east, from the White Spot. It seems picked out by very small white dots arrayed in an arc that could well define an outer rim wall of a huge basin.

However, some of the features appear to be albedo variations not associated with shadows. That would jibe with the Hubble images showing varying albedo features on the fully lit disk. In particular, the White Spot looks more and more to me like a volcanic construct than a crater. It just resembles the volcanoes on Io more than it resembles a crater, what with the lack of rays and the partial arc of darker material to the north and lighter material to the south. Sort of like a bruised-eye effect, which is exactly reminiscent of Ionian volcanoes, to me.

Of course, it could be an impact crater with an extremely complex ejecta pattern. But any crater that remains that bright ought to have generated rays, and as we get closer, we're not seeing any evidence of such.

Also, maybe it's just me, and maybe it's just something inherent in the opnav camera, but... Ceres doesn't look completely round to me, here. It looks oblate, like it was squashed at the poles. Since we have rarely been able to resolve Ceres as a disk, has there been much in the way of published observations relating to its relative roundness? Or are we looking at its possible demotion from dwarf planet back to just an asteroid...?

-the other Doug

Dr. Schenk, I see exactly what you're seeing as far as the linear (or arc-defined) structures are concerned. I do think that Toma's nod-back-and-forth animation helps incredibly in just staring at the surface relief and examining he shadow patterns during the small slice of rotation that we can see from the opnav images:



When you can just stare at it for a bit, you can see the depressions and their related shadows quite clearly. The large east-to-west trending set of overlapping basins (if that's what they are) that you identify with your blue lines are very clear. But even more clear is a very long, not very arcuate feature that just begins to disappear over the eastern horizon that is the eastern extension of this system. It is more reminiscent of a straight-wall feature than a basin rim, unlike the remainder of what appears to be this chasm system. Or an actual chasm wall as opposed to a basin rim.

When seen in the nodding image, it all gives a very strong impression of a very wide (as wide as the largest basin encompassed within it) chasm, that runs from a rather narrow head on the eastern horizon through a large broadening into the largest of the basins it encompasses, and then narrowing as bit as it heads slightly south of west to the western horizon. And while the view off of either horizon is unavailable, it gives the impression of a great-circle alignment to Ceres' surface -- i.e., running along a rough circumference of Ceres' globe, but tilted to its equator by about 30 or 40 degrees. What see see now is the southern arc of such a great circle. It will be very telling if this system extends into the northern hemisphere on the opposite side of the planet, eh?

I am *so* looking forward to seeing the next set of even more detailed images, hopefully some time next week...

-the other Doug

I gotta think the bright spot is an extremely fresh crater into an ice layer. Maybe not that old, either -- to escape the darkening effects of solar radiation and small impactors and be that relatively bright, we could be looking at a feature formed in the last few millennia, if not centuries.

The next question is whether or not the entire crust is basically ice, or something else with pockets or discontinuous layers of ice. That could explain why an impact in one location would be super-reflective while one only a few hundred km away is not.

-the other Doug

I absolutely agree with Bjorn and bellaraphon1 and MarsInMyLifetime, and take back some of my earlier comments about the "dark ribbon." It really looks like a very wide chasm system running from southeast to just south of due west, starting out the width of what looks like a large impact basin but stretching on, either the crater chain of all crater chains or an actual rift valley the likes of which dwarf even those on some of the Saturnian and Uraniun icy moons we've seen.

I'm almost brought to mind, looking at the terrain that begins to peek out from around the right horizon, of a massive disruption of the planet and re-assemblage of the chunks in somewhat random orientations. Ceres also looks a lot lumpier, i.e. non-spherical, and to a greater degree, than I would have thought.

But, again, we'll know better very, very soon.

-the other Doug

I'm beginning to come of the opinion hat the "dark ribbon" feature leading from what now appears to be the prominent southern basin to the west to a second, smaller basin is an albedo feature. It is too far south of the apparent basin rims to be a simple shadowing, and doesn't completely follow the basin rims. Also, if it's shadowing, it seems to be from some type of central peak units rather than from the rims, and stretches across the rims between two basins, which I wouldn't expect even complex central peak or ring structures to do. And, finally, it doesn't seem to be discontinuous as it tracks between the two basins or north-west to the "Y-shaped" bifurcation. (These details are visible, if barely, in the Hubble images, as well.)

Of course, this could be the "Martian canals" effect, where fuzzy unresolved details seem to grow into continuous linear features by dint of the mind's eye. I mean, it could be a chasm feature that has penetrated and degraded the basin rims -- after all, in some of the recent images, it's extent almost makes it look like a crack in the world defining an off-equator circumferential chasm system.

The one statement anyone can make for certain is that we'll know far better in a few weeks.

-the other Doug

Will the new opnav images be looking at the same hemisphere as the last set? In other words, will we be seeing the white spot at greater resolution, or the other side?

Don't get me wrong, I don't care which side we get to see. I'm happy to see any of Ceres at ever-increasing resolutions. This will help complete my mind's-eye-view of our solar system, and I can hardly wait.

Of course, the remainder of what I need for that wonderful full visualization of our solar system has to wait until July, at the earliest. So, no matter what, there is always more time to wait... but wonders at the end of the rainbow.

-the other Doug

Great work, Bjorn!

It seems obvious that the "head" of the dark horizontal feature you mention is surrounded by a brighter annulus -- at least, several brighter points appear in arcs around the place where the dark steak spreads out into a "handle" shape, the arcs defining what looks like a large encircling crater or basin. It certainly gives the impression of a large crater or small basin in the animation, though of course it's no more than an impression, at these resolutions.

However, if the center of the "handle" were some kind of eruptive feature, the bright annulus could be extent of the outer eruption ring. (Think in terms of Ionian volcanoes.)

It's quite exciting to know that we will have much better views within weeks!

-the other Doug

Do you think the "munging" might be one last attempt by the OSIRIS team to resist releasing their images, by releasing degraded versions? Or does it look more to you like these things are the result of processing by the people who actually published them? I mean, even at the best native pixel resolution, a lot of them look, I don't know, almost de-focused.

Also, am I right in assuming that all of the various releases of these images, including the ones released on ESA's own website, have the same issues?