Ceres is suppose to have a very low axial tilt, estimated at three degrees or so. We should therefore be seeing a similar low sun angle near the northern pole. But we are not seeing the same topography there. Either the tilt is more pronounced than was believed, or else the northern hemisphere is smoother. Or perhaps being oblate the way it is exaggerates the lighting effects of the tilt.

Granted that the spacecraft is getting a better look at the south pole too, but still...

Just noting that all these white spots appear in the north, at this point I'm betting there are other differences there too, topography possibly being one of them.

I too wondered about the smoother northern limb, but I think the southern limb appears rougher because of the interplay between lit and shadowed areas that are not quite discernible at the current low resolution.

A low axial tilt but a considerable orbital one. Do we know the actual viewing and lighting geometry here? It's fairly obvious we are not viewing at full phase.

'Great White Spot' debate... luv it.

Know I am waving my hands to the choir here but.... how Cool is this?
Here we are debating features on a world all of humanity is seeing for the first time. In all of human history
there is only One first time. And we are active participants. Thanks to this forum.

When the new digital text books are written.... we were there.

Holder: "Ceres is suppose to have a very low axial tilt, estimated at three degrees or so. We should therefore be seeing a similar low sun angle near the northern pole. But we are not seeing the same topography there."

No, that's not how it works. We are viewing from south of the equator - the axial tilt tells us the sun is overhead near the equator, but we are looking from further south. At the south pole we are looking over ridges and crater rims and seeing the shadows they cast. In the north, the ridges and rims block our view of the shadows. It's totally different viewing. Compare it with a view of an almost full moon - on one edge the terminator shows stark relief. On the other side you see nothing but albedo markings.

Phil

Just me?

One problem with the white spot is that we really do not know about a possible contrast stretch in the released images (my guess though is that there is little or no contrast stretch). Also it's only bright relative to the surrounding terrain, in reality it's probably not white (although that depends on its size). My guess is that this is simply a small and very fresh impact crater (or at least something associated with an impact crater). I'll be very surprised if this turns out to be something else.



As Phil mentioned, the viewing/illumination geometry means that we see the terminator in the south and this makes the southern limb more irregular. This is a schematic view showing the viewing geometry on January 25 (it hasn't changed much since then):

Fresh impact crater was my first impression... but not small and no fresh ejecta. More going on here.

Looking at the Ceres Layer diagram on this web page
http://www.space.com/22891-ceres-dwarf-planet.html
I would think the white areas are where an impact has blown off the "thin dusty outer crust" and exposed the water-ice layer below.

How much of an impact does it take to eject stuff at escape velocity.
Does the vaporized water fall back onto the surface like snow (ice crystals)?
How deep would an impactor go?
Would the ejected material shoot out in a thin jet?

Thanks for showing the viewing and lighting geometry, Bjorn. While Ceres has little axial tilt, the view point is from above Ceres' southern hemisphere, so we see the southern terminator and the south pole, but not the north pole. There may well be topography near the equator and northern hemisphere, but albedo differences will be far more apparent than topographic shading. So I doubt that we are seeing any topography with respect to the "Great Bright Spot".

And Bjorn, it may well end up being the ejecta of a fresh impact crater, but I am just surprised there is no hint of rays extending from the spot, but you do see them from some of the other bright spots. It just makes me want to consider other posibilities, either the bright limb of an impact crater, like Umbriel's Wunda, or maybe it is a mountain, like the bright peaks of Callisto (but those are much smaller...). And there is the question of the dark patch next to it, which kind of reminds me of the dark ejecta around Oppia on Vesta.

Ah yes, putting it that way... you're quite right. So... still too early to tell.

Very preliminary OpNav2 (based on Ceres_OpNav2_Anim_v2.gif) and OpNav3 (based on pia19179-16.gif) merged rectangular longitude/latitude maps show the respective surface coverage of the two sequences:

(The two maps are horizontally shifted)
For OpNav3 the rotation steps are about 6 degrees, about three-fold the steps for OpNav2.
The OpNav3 map version is work in progress, and needs more accurate registering to resolve more detail.

This reminds me of the joke:

Q: Why do New Yorkers wear black?
A: Because there's nothing darker.

My take is that the white spot is dark, and everything else is darker. Very curious to see if this is true.

Perhaps not dark, but if brought elsewhere to a lighter shaded place we could very well see it as grey.
Whatever caused the bright spot originally, have since been shaded by dust or any other process.

Basically I agree though, that the bright spot might appear white against the rather Dark surface of Ceres.

I took the animation from Toma's post, reduced the gamma with a slight compression to the color space to increase contrast of surface features. They're composited together and rotated 90* to the left because I find it easier to track elements that way.

http://i.imgur.com/98lPRNQ.gif

Is the apparent blooming of the brightest points, an artifact of the low quality? They seem to get much brighter as they reach the closest point to the camera.