What’s causing Ceres’ white spots? (Synopsis)

“One of the dreariest spots on life’s road is the point of conviction that nothing will ever again happen to you.” -Faith Baldwin

Bet you thought you knew it all about the asteroid belt. These frozen, ice-and-rock worlds orbit farther out from Mars, closer in than Jupiter, and occasionally get hurled towards the inner Solar System by gravitational interactions. But the largest world, Ceres, at just about half the diameter of the Moon (or the size of Texas), exhibits an unusual surprise: a brilliant set of white spots at the bottom of one of its largest craters.

Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

While the speculation abounds from simple (water-ice) to the astounding (aliens!), there are only three realistic possibilities given what Dawn has seen so far. What's even more exciting? It's already got the equipment on board to decide which possibility is the right one!

Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA / montage by Tom Ruen. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA / montage by Tom Ruen.

Come find out the whole story behind Ceres' white spots -- so far -- over at Starts With A Bang!

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So far the best theory I've read has the white spots, of which there are multiple spots in multiple craters, are salt crusts. So far they've already proven that Ceres has a significant amount of water, up to 200 million cubic kilometers worth of water. They believe that up to half of the volume of Ceres is water.

The theory is that impacts bring water to the surface where it freezes and sublimates away leaving behind a white crust of salt. We should know for sure shortly when the slow the probe down and drop it closer to the surface.

I hadn't previously associated the "aliens" idea with the idea that it was emitted light, and I don't think that's a necessary premise -- artificial, high-albedo structures would also fit.

Of course I know that this is wishful thinking. But I'm still hoping. ;)

What sort of albedo (fraction of light that is reflected) is required to explain the observations? Are these spots white as the driven snow, or grey looking like brillant white because the surroundings are very dark?

Any idea, how old the crater is? If it was recent, then it would be easy to imagine that some nearsurface water (brine?) melted and filled up the low spots. But I imagine that once the water/ice is gone, it would to become coated with dust/debris. What we've learned so far from comet/asterioid visits, is that the surfaces look like dusty rubble, more dessicated than the even dryest deserts on earth.

By Omega Centauri (not verified) on 19 May 2015 #permalink

I'm with you Nemo - it's the hull of a hidden generation ship, or better yet, a white monolith. Sure, it'll turn out interesting in a more reasonable way, but we can dream.

I could also imagine residual heat from the impact, leading to some sort of geo-thermal like activity. Perhaps a wee bit of steam is making it to the surface (at near vacuum pressure of course), and some condenses as frost/snow before it all is lost to space.

By Omega Centauri (not verified) on 20 May 2015 #permalink

Whilst many accept Biblical accounts of, Water into wine and feeding the many with a couple of fish and a loaf, these tales are believed by otherwise good folk who reject the concept of Aliens. But why? It is our social programming and moral cowardice. How long would your academic life last if you were to suggest that the white spots on Ceres were the result of Aliens? Sadly the Alien camp is populated by too-many (not all) idiots with bizarre haircuts and idiotic websites. Why is this? Perhaps it's to turn the Alien and UFO camp into a circus, sprinkled with Alien Pixie- dust and wishful thinking. But if we ever did meet Aliens, the social upheaval that would follow would be horrendous and that dear reader, is why it is turned into mind-mush and bad haircuts. ‘Blessed are they who disbelieve.'

By Aron Kfir (not verified) on 20 May 2015 #permalink

I don't know much about this science mumbo jumbo, BUT I LOVE THIS BLOG!

Created by aliens - certainly not but more importantly, I am just happy it doesn't resemble the Android icon or the Apple logo— whew!

Sadly the Alien camp is populated by too-many (not all) idiots with bizarre haircuts and idiotic websites. Why is this?

Because there's no evidence for aliens?

The alien camp is filled with charletans and psuedo-science. And certain media outlets like the history channel have fallen for this stuff hook-line-and-sinker. So clearly any claim for aliens should be treated as 99.9% likely to be bogus.

Thats doesn't mean they aren't possible, although what we know about for instance special relativity makes interstellar travel appear to be much too difficult to make it likely, even if intelligent civilizations are common.

By Omega Centauri (not verified) on 20 May 2015 #permalink

"Whilst many accept Biblical accounts of, Water into wine and feeding the many with a couple of fish and a loaf, these tales are believed by otherwise good folk who reject the concept of Aliens. But why?"

Only those brought up in a faith that has that story in it is it possible to get people to accept that story. Other regions have other silly myths, which everyone who believes in the Bible story thinks is ridiculous rubbish.

It's no more ridiculous than believing Santa Clause or the Easter Bunny.

It's just that most people get over it when they try to work it out.

As you say, social programming.

The cowardice is really just terror. Some people really are very, very scared of not existing, since they're the entire reason why anything is here.

And religions continue because it feeds that ego and gives a fake feeling that can hide the stark terror of contemplating death for themselves.

The Head Peanut In The Peanut Gallery Is Barking AGAIN.
History is full of people who believed a concept against the main thinking only to be proven correct later.

You should get that anger issue checked out. I think the UK has free health care, perhaps you can find some help. Here I found a link:
http://www.counselling-directory.org.uk/anger.html

By Ragtag Media (not verified) on 20 May 2015 #permalink

"History is full of people who believed a concept against the main thinking only to be proven correct later."

No, it's pretty damn empty.

Only if you select the very few and ignore the billions who believed "something different" (say, for example, that "NASA are lizard aliens, look at the red snake tongue they use in their logo!") and were completely batshit nuts.

It looks like NASA will soon know the answer as to what the white spots are. They just have to count the votes. If you want to be part of determining facts by popular vote and help to build a consensus, you can vote here:

http://www.jpl.nasa.gov/dawn/world_ceres/

" It's salt, Jim, but not as we know it ... "

"..and were completely batshit nuts."

Much like yourself, Rag.

Leave it to Wow to bring up religion...

It's just light from the camp fires. We're spending Memorial Day weekend on Ceres. We are sorry for all the excitement.

Ethan, I don't get this part:

"It’s a fun idea, but if that were truly the case, you wouldn’t see such tremendous brightness/albedo changes as the angle of the reflected sunlight changed relative to the spacecraft."

Looking at the images you provided, I actually _don't_ see "tremendous albedo changes". They are constantly very luminous -- at least in the images you've shown. While I find the consipiracy theories laughable, the spots do look more like emitted light; they actually resemble clumps of city lights as seen from the orbit.

I have been wondering for some time whether the spots are specular reflections, like the ones you get from lakes on Earth. Tom Ruen' montage makes it clear that is not the case - that the light is either a diffuse reflection, or else something is actually glowing. I second Omega Centauri's question: "What sort of albedo (fraction of light that is reflected) is required to explain the observations?" I'm really looking forward to results from the mapping spectrometer. I don't know about its sensitivity or resolution. Is it in use yet? Can it resolve the white spots?

By Jim Van Zandt (not verified) on 23 Jun 2015 #permalink

Looking at the recent photos from a lower orbit, there seem to be quite a few more bright spots in many places other than the first crater shown. One of the shots shows the crater in very low light, but the spots are still well illuminated. Trick of post processing, or self generating light source? It gets more fascinating. Hopefully, more data in the next lower orbit coming soon.