NASA released an animated sequence of images from NASA’s Dawn spacecraft today. In their description, they call attention to the mysterious white spot (actually a close pair of spots) on the dwarf planet’s right side easing into view in the animation’s last few frames. It is pretty interesting, but it isn’t what caught my eye. I was more taken with the bright spot that is leaving as the other arrives.
I put an arrow above it to make it easy to pick out. Ceres is covered in mysteries, mostly in the form of white spots. I was so fascinated by this one I ‘remastered’ NASA’s animation to keep that little white spot in the same location. Do you see what it is doing? It is fading away. This may come as little surprise since it is falling into shadow, but the way it fades is different than area surrounding it.
I am not a scientist. I like to think about science and daydream, but while both of these qualities may be good for real scientists, I probably lean a little too much on the daydreamy part, and a good deal too little on the part where you work to prove or disprove your ideas, especially if there is going to be any math.
One theory about these spots is that they may be ice, formed on crater edges. Another is that they might be icy volcanoes. That little spot I pointed out could be doing its thing because it shines, glistening like ice, or it could be the slowly evaporating ejecta of an ice volcano, something more like snow.
Meanwhile, if we go back to the other, more famous spot, it does not fade or change in the same way. It just looks super bright, all the time. It doesn’t look like ice, to me, so much as the creme filling of a Charleston Chew. This is probably not going to get traction as a leading theory, nor am I suggesting the inside is actually nougat (though that would be pretty awesome.) But is does look bright and not icy in these initial images.
Because I am not a scientist and, more specifically not a scientist on the Dawn team, I don’t know how bright Ceres actually is or how this camera is calibrated. I do know the moon, our moon, which looks pretty white from the Earth when its full, is actually a pretty dark grey. It just looks super bright in the night sky because the sun is giving the moon its all, whilst leaving us in the dark for a few hours, to sleep, or to romance, or to star-gaze. Perhaps something similar is going on with those bright spots?
Check out this image from an amazing animated set NASA released a short while ago. The brightest spots don’t just appear to reflect brightly, they seem to practically glow.
So what is my point? I’m not sure I have one. If you were hoping for some cool conspiracy, I haven’t got one for you, though Ceres does have fewer craters* than expected. Where did they go? Actually, this probably suggests a surface that is renewed by some kind of activity.
More interesting to me is the idea that Ceres mysterious white spots may not be the same. The dimmer ones, like the one I companioned with an arrow, may be ice, or frost or something yet unseen. The larger one, like the one everyone is so excited about may be something more permanent, like enormous deposits of chalk or cream, kicked up by a crashing meteor. (Of the kind of scientists I am not, a space geologist is clearly one.)
My nutty animation is not the only evidence — in fact it is surely the least of it. Last week Nasa released a beautiful color map of the diversity of Ceres’ surface, as well as a series of images showing Ceres in different spectra of light and not all the spots show up the same. What at first looks like it will be a dull, cratered ball of rock and dust, is only just beginning to reveal its secrets.
*I know it looks pretty cratery, but it has fewer than knowledgeable scientists expect. Ceres should not feel in any way embarrassed about itself. I’m sure it has the perfect amount of craters.