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Ceres Fan Club


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I think Ceres is a much neglected member of our solar system, probably because it is 'only' an asteroid (actually it is a dwarf planet, and when it was discovered it was regarded as a full-strength proper planet).

It is a unique world, made of brine and mud and very soft. It is the only round, brown body in the solar system. 


When the world was explored by the Dawn probe, the great surprise were the bright spots, which turned out to be salt deposits left behind by briny water venting into space. The water comes from a substantial reservoir in the little world's interior. Two surprises in one - cryovolcanism closer than Jupiter's moons, and persistent liquid water in the asteroid belt. The belief is there is enough radioactive heavy stuff in Ceres' partially differentiated core to keep the water flowing (plus the water is briny, which lowers the freezing point). As an aside, how come it is reasonable to think Ceres is warm and active volcanically, while our much much larger Moon is considered too cold for ongoing volcanic activity? Here is the crater Occator and its dramatic salt fields:


Ceres has more dramatic volcanic activity than Occator. It has the tallest mud volcano in the Solar System, Ahuna Mons! Earth, the only other world I know of with mud volcanoes, tends to have flat mud volcanoes because of its stronger gravity. But in the 0.03g of Ceres, the mud can pile high. 


Ahuna Mons is 4.1 km high and is unrivalled on Ceres. But there are many smaller mountains (called tholi) that may have been giant mudpiles like Ahuna but have slowly subsided back into the surface since their volcanism ceased.

Aside from craters, saltpans and volcanoes, Ceres also has mysterious grooves (catenae):


Ceres has been wet and rich in clay for billions of years. Not only is it a great world to explore for signs of life, due to it's small size and primordial nature, Ceres might have the oldest life in the Solar System!

Edited by Ags
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+1 for the Ceres club!

I remember an illustration in one of my dad’s old astro books of the solar system that shows Ceres in the planetary line up between Mars and Jupiter, as though it was “just another planet”. (And doesn’t show Pluto as it wasn’t yet discovered).

So yes, I’ve also thought of it as a bit of a “forgotten child” of the solar system.

Thank you for sharing the fascinating information about its incredible geology/ just goes to show how wonderful the universe is.

I think the position at the moment is pretty good for observation; if the clouds ever lift!

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I want to try spot it if we get another clear night this year, I confess I have never seen Ceres myself. I think it is wonderful how we send probes to new locations, and every time the target brings surprises and becomes more interesting... Ceres has a lot of water - estimated to be as much as all the fresh water on Earth.

I do think that if I ever stood on the surface of Ceres, I would have the terrifying feeling that I could just drift off into space if stepped forward too vigorously. No risk of that - the escape velocity is is over 1000 km/h, but the high jump record should be something like 80 meters.

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Excellent information, thank you. I too only recently found out about Ceres at a talk I went to just over a week ago. By luck, a couple of days later was a clear night and I was able to observe it. It's more or less at opposition now, so a perfect time to see it. It's just off the tail of Leo, and will pass "through" the M100 galaxy around 28/29 March.

Edited by Captain Scarlet
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Thank you for an excellent post.

I never realised it was such an interesting and active place.

How different to the world in the 'Expanse' story on Amazon TV.

How different to book I read over 50 years ago. A mission to Ceres that had an in flight problem.
I'm sorry I don't remember the title - actually I have not thought about the book for decades!
The crew got there, but were stuck. No mention of tiny gravity. An ocean was mentioned.
Actually the ocean produced enough seaweed for the crew the construct a huge arrow pointing to their stranded rocket.
I believe it had a good ending but I don't remember the details.

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Asteroids are generally thought of as rocky rubble, whereas Ceres is perhaps 50% water by volume. Of all the bodies in the entire inner solar system (everything within Jupiter's orbit), only Earth has more water than Ceres. Those white patches in Occator crater hold the clue to the mystery - the salt patches are not common table salt, but are a more diverse mixture including ammonia salts. Ammonia is very volatile and indicates Ceres formed further out beyond Jupiter. It was kicked into the Asteroid Belt when Jupiter's own orbit went through changes in the early days of the solar system. 

It makes me think that in the early days, Ceres may not have been a faint object in the Earth's sky - perhaps it was surrounded by a splendid cometary halo as its outermost ice layer sublimated, eventually leaving behind the dry salty clay crust. Even today Ceres has a tenuous atmosphere of water vapor (although I think calling it an atmosphere suggest some degree of gravitational binding, whereas it really seems to be H2O that hasn't drifted away yet).

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Thanks for the heads up Agnes. i made a point of catching up with Ceres last night - a total first for me. At Mag. 7.0 I found it to be the brightest thing in what seemed to me to be quite a sparse spot in Coma Berenices. A dull cream in colour though only a stellar looking point source dull cream at 200x. Fantastic to contemplate what i was looking at while looking at it. Cheers

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