Yep dvandorn... agree bright spot suggests a very fresh impact crater... and a very icy subsurface at this point of impact. Best part is we will know much more very soon.

Craig

Perhaps, but the fact that it looks like it is at the center of a large crater is interesting. On Umbriel, the bright ring, Wunda, seems to follow a crater rim. And on the nearby Vuver crater, there is a bright spot at the center. Vuver also appears to be bisected by some sort of rift. It is unlikely these are fresh craters, and if the bright spot on Ceres is simply a fresh crater it would be an amazing coincidence given its location.
Click to view attachment

Fascinating tedstryk. We will see....

Luv this...

Do not want to go off topic... but Uranian moons just cry out for another mission. Sad thing is that time is against a single human lifetime to fully characterize these worlds.

Craig

Since New Horizons 2 never flew, which would have mapped the moons during equinox, any mission in the next few decades is going to see the northern hemispheres of the moons, meaning that much of the area mapped by Voyager won't be visible (and thus won't be improved upon) until the late 2040s (other than what can be seen in Uranusshine - hey, NASA, I know what I want for my 70th birthday). Which brings me to a question. Ceres has an inclination of 10% (not nearly as significant as Uranus, but relevant nonetheless). Where are we in its seasonal cycle? Will (or might) Dawn hang on long enough to map both poles?

Anaglyph and x-eyed version of the post-processed animated gif, derived from Ceres_OpNav2_Anim_v2.gif:

Wikipedia says its only 3 degrees. we should be able to get both poles pretty well.

The fact that there is no mission to Uranus in the works -- and that any spacecraft arrival to the planet is decades away (at the least) -- truly depresses me. I would LOVE to see its moons to get the Cassini treatment.

The Ceres/Umbriel comparison is striking. Craters do not surprise me, but I would have expected a smoother surface just because of the warmer temperature than all other explored icy bodies. Perhaps these early, low-res images are misleading in that regard though.

I'm seeing 10.593 in the facts on the right-hand side of the page. Where are you seeing this?

I think DrShank means the axial tilt is 3 degrees.
The 10+ degree inclination is the overall tilt relative to the ecliptic, so it shouldn't be important for local seasons, right?

That's right: the orbit of Ceres is inclined 10.6 degrees to our orbit (the ecliptic), but its equator is inclined 3 degrees to its orbit (axial tilt, obliquity). Only the latter matters for seasonal effects.

Phil

Gah! This is why I shouldn't post in the middle of writing a self-study for work.

Thank you Bjorn and Thoma.

Looking at the animation I tend to think what we might interpret as a line in the south near the bottom might be the southern rim of two craters that the eye want to connect. They are still interesting since appear to have a double bottom, could it be that the impacts excavated fresh ice that later sublimated creating that double bottom?
The linear feature at right might be one actual chasm or whatever we should call it.

And @antipode, yes the idea of a smooth ball is certainly gone, if craters are smoothed out at the equator and more prominent at the poles is something we still have to learn from better images.

I'm wondering, given the gullies we've seen at Vesta, if any possible canyons (or inevitable crater rims) have similar features from the same sort of ephemeral flows of liquid water? Definitely something to keep an eye out for as Dawn starts spiraling into lower orbits towards the end of the year....

As much as i hate to go off topic, there is some skepticism regarding the Vesta gullies, which fall into the same category as the Martian gullies; both could be interpreted as dry avalanches. The water content of Vesta rocks and the meteorites is a lot lower than on Mars. I can't speak as an expert in such matters except to say it is not yet an iron-clad slam-dunk case.

back to Ceres, here is my crude attempt to map project one of the images and do some sketch geology. It is not much more precise than Phil's map so is not an official product or anything. I think we can expect one from dlr in the next few days. but i show it to join in the fun!

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 know these are still not great resolution images and it is unwise to be too bullish about what one might see, but as soon as I looked at these I thought "Miranda", it is a similar size too. Wouldn't that be great. The apparent "V" shaped ridges in the Northern hemisphere, the great gouge almost circling the Southern Hemisphere. Like others here I certainly was not expecting such an uneven surface. The big light feature in the North, I think is almost definitely a crater, possibly pretty recent, and there are two other very likely craters near the South Pole. I agree with dvandorn's description of the apparent great chasm/valley/rift. There might be three other bright circular features, they show up better on your projection images. After that everything is a bit too indistinct to characterise other than the Southern Polar region looks to have been severely battered by impacts.

Just a nice little teaser though.

P.S. I vote for a Uranus orbiter mission too. Its the obvious next step scientifically and technologically and has to be the most intriguing if only for that axial tilt and the variety Voyager saw in the moons.

I also found the flip movie useful. stereo can do the same thing by effectively doubling the information, even is there is little relief. I tried some stereo here, too but it was weak due to the low resolution. soon.
but even Tethys looks unimpressive from this distance, and it has basins 4 to 9 km deep.

I am also getting a slight Europa-esque feeling from Gerald's animation. The reason why is that it looks like as if those chasm-looking things contain islands/peninsulas of highland; like tall icebergs frozen in. Then again, I guess the Tethys images at low resolution can also slightly give an impression like that, and that the height differences would appear to be much greater than on Europa.

(edit: trimmed down post)

Regarding the bright spot, I see more a depression than a dome or mountain.
So if it is a bright depression, It may be an impact crater but I prefer the hypothesis of a caldera with a bright flat surface above a hot spot. In other words, an ice pack (or a "banquise" as we call it in France) lying above a pocket of liquid water heated by the volcano.
I may be wrong but that's my bet!

My bet is that it's 'just' an extremely fresh crater. However, the apparent absence of significant rays may discount this.

The magical part here is that we'll soon know. That's one of the best feelings there is.

Any rays would be too thin to be properly revealed at this resolution, surely? The bright spot is turning out to be rather small itself.

With few pixels, the brightness in the one pixel makes this bright spot appear much larger than the supposed crater may actually be. By the next session, I think the size will match the pixel, and soon thereafter we'll get some actual detail of it. If it is truly a case of excavated ice, the thinly spread rays may have sublimated quickly based on similar observations of scraped ice at the landing site of Phoenix.

Here is another stacked image from the January 26 images, this time from the first 9 frames (the one I posted earlier was from the last 9 frames):

Click to view attachment

I also did some anaglyph experiments but the results were very bad.

Due to Ceres' rotation the terminator looks somewhat different here. There is definitely a crater very near the terminator at lower right.

I'm starting to wonder whether Ceres might have a depression/chasm that extends at least 180 degrees around it. I'm far from certain of this though - the next set of opnavs should be interesting.

If there are linear features on Ceres, how could they have formed?

The chasms on certain gas-giant moons (Tethys, Titania, etc.) were probably caused by tidal interactions with other satellites. There aren't any obvious interactions with Ceres that could form such features (though things could have been different in the distant past).

The fossae on Vesta probably resulted from tension caused by impact-basin slumping. So far, there are no obvious signs of similar basins on Ceres.

My guess is that we are seeing chance alignments of crater shadows (and shadows between craters), with a sprinkling of pixel artifacts here and there.

Maybe not chance alignments, but crater chains made by "rubble pile" asteroids that break up just before they hit.

Because ice expands as it freezes, you expect extensional fractures on icy bodies that are large enough to have partially melted in the past. The freezing internal ocean would expand, forcing the solid and brittle crust to crack.

Thanks a lot Bjorn.
This one is definitely better than HST's

The latest Dawn Journal entry contains an updated imaging schedule. The next imaging session appears to have been moved forward one day: to Tuesday next week.

Most importantly, the table there also contain phase information for Ceres as viewed from the spacecraft. The illuminated portion of Cere's surface is as low as 18% for the image planned for 10 April (9.6x Hubble resolution, best resolution acquired thus far).

Excuse going slightly OT, but does anyone know what the IAU naming convention 'theme' will be for features discovered on Ceres?

P

Indeed. Simple and great. Thanks a lot !

Yes this is the reason we look for cracks, though I am somewhat sceptical about one of those features and are happy that I am not completely alone on that, with a nod to Gladstoner.
A slight uplifting could also happen when deeper layers of water freeze solid. Comparing with what a pond look like when it freeze solid, the cracks and uplifting would be quite small, so in the case for Ceres it can still not be seen in the rough resolution we have so far.
That is something we have to wait for until the images we receive on the final approach, and they should be there, it would be very surprising if Ceres have maintained a liquid water interior.

You have to poke around a bit at the Gazetteer for Planetary Nomenclature, but it's there. Scroll down past the major planets to get to the asteroids. For Ceres, craters are global agriculture and vegetation deities, and other features are agriculture festivals.

The excellent rocker image gives a strong impression of a continuous chasm, but outside of that I get the impression of preserved crater walls down to and past the limit of resolution. As long as we're doing moon analogies, mine would be Mimas with the dense cratering.

Thanx illex, that makes perfect sense of course.

P

I suggested plate tectonics earlier not only because of the the apparent rift mechanism but also because of the seeming highland region that nods in and out of view on the lower right of the animations, particularly Tomislav's (https://www.flickr.com/photos/tomabandin/16...838330/sizes/o/). This highland appears both higher and smoother than the rougher "cratered lowland." The elevation and texture difference seems clear to me. What are the chances this smoother landform is due to an outflow process lurking behind the right limb? Time will tell!

Now that we are getting pretty close... which geological features will be revealed in the next days?

For the french community, here's an outreach article that try to answer that question (from the swiss astronomical journal)

Yeah that's right and since Ceres was a roman godess, I guess female ones will get the first run for naming. So I hope IAU got Sarahka high on that list since its one such godess from the arctic region which I think would be very suitable for a frozen world like this.

The word Ceres is the root of cereal for you English or American speaking members here. I hope that does not mean we will have other features named Müsli and Cornflakes. But the suggestion of naming after 'agricultural festivals' seem almost as deranged to me, will we have hills, ridges and chasms named Oktoberfest and Skordefesten? To me, that sound almost as deranged.

Also French (céréales)

"But the suggestion of naming after 'agricultural festivals' seem almost as deranged to me"

Alas, dear Ant, you are mistaken. It is much more probable that these names will be from ancient Roman agricultural festivals, of which there were many:

Sementivae, Cerialia, Robigalia, Fordicidia, etc.


Phil

I'm hoping they discover a feature that can be called 'Corn Palace'.

http://en.wikipedia.org/wiki/Corn_Palace

Yes of course, my post was to be read as mostly humorous, I added that item about Müsli for that purpose.
Though the Skordefest and Midsummer festivals most likely are as old as the Roman ones, dating from from the Vendel age, so who knows. =)

Thanks a lot SpaceScout : yes indeed, all the scenarii are there!

Ceres_OpNav2_Anim_v2.gif projected onto a longitude/latitude rectangle, assuming this globe


for all images, and a rotation in 2-degrees steps:


(edit: fixed links)

^ it seems that you forgot links.


Since I don't have a very good intuitive idea about sizes measured in pixels, I created this infographic about how big Ceres will be at native resolution in the framing camera's images in the next weeks to come.

Click to view attachment


Note how Cere's apparent size makes a big jump from 12 February to 19 February, and then the growth slows down - and even reverses for the next image taken (not included here) - due to Dawn's orbital insertion path.

That's really helpful.

In terms of the change in circular area imaged, the next 3 images will essentially triple the number of pixels from the next prior image (ignoring illumination):

265%, 25 January to 3 February.
299%, 3 February to 12 February.
334%, 12 February to 19 February.
131%, 19 February to 25 February.

(I'm restraining myself from going needlessly further nerdy with this...)

The next few weeks will be illuminating

nice

Thanks! It should be fixed by now.

I was inspired enough by Habukaz' graphic to complete my own and post one or two on my blog:

http://stereomoons.blogspot.com/2015/02/ce...-into-view.html

here is a rendition with Tethys images substituted in at comparable resolutions.

Thank you Habukaz and DrShank for the comparison images.

Already looking forward for the image for this day, but yes, it will take until February 19 before we actually get out of the "speculation phase". =)

Nice. A visualisation of the phase was a crucial thing missing from the last sphere in my illustration.

Speaking of which - I know it was speculated by some that Ceres could have a tenuous atmosphere. I don't know where that kind of speculation is now (except from the detection of water vapour by Herschel), but I guess the 25 February, 1 March and 10 April images could shed some light on this?



I'm placing my bets on that the images taken today will show whether or not the linear features are real. You can (just barely) see them in last week's raw images.