equatorial ridge line

http://news.bbc.co.uk/2/hi/science/nature/4157689.stm

this is so odd....really, really odd.

Very strange. Sort of looks like tectonic force created the ridge. I can't imagine what could cause that feature.

Looks like a big Pac Man! Fly too close and CHOMP!
FMR

Reminds me of Danish x-mas dumplings:

"unknown mechanical force" eh???

Meebee it was a moon with it's own ring system and the orbits of the particles decayed. Came down over the eons like a passel of satellites and built up a equatorial ridge.

My guess is that it's the remnant of a launch accelerator system which was once used to fire payloads into orbit around Iapetus. The payloads would have had low-thrust engines attached, which would continue to operate after they had reached orbital speed at the end of the ramp, ultimately transporting the payloads to their final destination. A rail along the top of the ridge would have provided magnetic levitation, to minimise friction. The ridge would have been created by firing payloads at sub-orbital speeds along the length of a small starter ridge, extending the rail slightly, and repeating ad lib until everything was complete. If I'm right then the ridge won't have a uniform height, but instead will be a ramp, following the equator as closely as possible. That certainly appears to be the case.

I think that the channel was filled with ice cream for the huge party thrown every Saturnian year. Neptunites from all over would line up and eat until they couldn't eat no more. Then one day the ice cream dried up and Neptune went away.

I suspect most readers will prefer the "decayed ring" theory to either the "launch ramp" or "huge party" theories; not for any scientific reason, but simply because any acknowledged alien engineering would challenge the accepted geocentric model of the universe.

But the Cassini picture is not the first one of Iapetus, and although it is of a better resolution than previous images, it is remarkable that a structure as prominent as the equatorial ridge was not noticeable in any of the earlier images; unless it turns out that the structure does not extend all the way around the equator, but only for a third or so of its length. Then the lack of previous discovery becomes understandable - most if not all of the previous images just happened to be of the other side of Iapetus, or happened to include only a small part of the ridge.

Then there is the remarkable smoothness of the terrain over which the ridge extends. Much of Iapetus is pock-marked like a teenager with a terminal case of acne, but that third of the equator over which the ridge appears to extend is remarkably smooth and crater-free. The ridge itself is smooth and straight and continuous.

Next, the ridge is extremely prominent where it meets the visible edge of the planet on the left of the photo. It is probably several times the height of Everest at that point, rivalling Olympus Mons on Mars. It may be an illusion, but the ridge appears to get gradually less prominent as we move towards the right, and to disappear entirely in the vicinity of the sunken terrain near the terminator (the boundary between illuminated and dark hemispheres).

Is it really beyond the bounds of possibility that the ridge could be exactly what it appears to be, i.e. a ramp? And that the sunken terrain near the lower end of that ramp is what it appears to be, a mine which was used to provide the material for the ramp, and then for further construction projects elsewhere?

To Halitosis: I don't think that the "ice cream" actually dried up - the whole of Iapetus is "ice cream" in the sense that it consists of materials which are potentially valuable to space-farers (mainly water ice, with impurities such as methane that could be extracted by melting). However, I agree with the rest of your analysis - the "Neptunites" were sated, and went away. Perhaps they could have taken everything, but they were considerate enough to leave something for those who might come along after them.

In the movie 2001: A Space Odyssey, the monolith was found around Jupiter. But in the book version, it was found at Iapetus. Arthur C. Clarke knew all about the weird light-dark difference of the moon, and presented this diference as an engineering artifact in building the monolith-stargate. I'm sure if he had also known of this bizarre ridge, he would have had a field day incorporating it into the novel.

Martin will correct me if I'm wrong, but I think, after debating him in a long thread on evolution, that he has a presupposition of design and purpose pervading the universe at all levels. A presupposition isn't quite the same thing as a theory, though. A presupposition does not necessarily have to be proved or tested -- it's merely presupposed. Science operates under the presupposition of metaphysical naturalism -- that the natural world is a self-contained thing, and represents the totality of reality. This presupposition can't be proved, either. And in fact, one could have a different presupposition -- such as one of intelligence and deliberate design pervading nature -- and still do science.

The only advantage Martin's presupposition has over that of metaphysical naturalism (and the two presuppositions aren't incompatible) is that it might be possible to prove Martin's presupposition -- after all, if the ridge really is a ramp, we could go to Iapetus and discover that. I don't think there is any way to prove the presupposition of metaphysical naturalism, however.

But, if one believes that design and purpose pervade the universe, where does one draw the line between purpose and nonpurpose? The Polish writer Stanislav Lem, in a novel, proposed that the expansion of the universe was being engineered and fine-tuned by alien intelligences. Is that possible? How could such a proposition be falsified?

No, Clarke did not at 1968 know anything about what Iapetus would look like close up - his wild guess is one of history's mystery great coincidences.

It was known in 1968 that Iapetus had a bright and a dark side. Clarke knew this, and put it to use in his novel.

In fact, Cassini himself (not the curent mission) discovered the light-dark contrast in 1671.

TR writes (reply 9):
QUOTE .. I'm sure if he (A.C. Clarke)had also known of this bizarre ridge, he would have had a field day incorporating it into the novel. UNQUOTE

Indeed. And the previously known strangeness is explicable in engineering/mining terms, if it is the trailing face of the moon which was mined (because it's safer there), and the leading face had any "slag" which was left over from the mining operations distributed over it.

I was going to write something about Cassini knowing that Iapetus had a dark side and a light side, but you beat me to it.

QUOTE .. Science operates under the presupposition of metaphysical naturalism -- that the natural world is a self-contained thing, and represents the totality of reality. UNQUOTE

Not quite. Science seeks to find natural explanations for observed phenomena. The presupposition is that the world is sufficiently ordered and predictable for this to be a worthwhile exercise, at least in the majority of cases and in those domains where science is traditionally applied. But few would claim that everything is explicable in terms of science. For instance, science might help you to devise a powerful weapon, but it won't tell you whether you should use it or not. It can tell you the consequences of using the weapon, but you decide whether those consequences are good or bad, and science won't help you there.

QUOTE This presupposition can't be proved, either. And in fact, one could have a different presupposition -- such as one of intelligence and deliberate design pervading nature -- and still do science. UNQUOTE

Exactly; so if we think of science as merely a method, and not as a philosophy, then it doesn't require a presupposition of metaphysical naturalism, or any other presupposition. Furthermore, there are still laws in a universe pervaded by intelligence and deliberate design; in fact, we really ought to expect more laws in such a universe than in one where randomness and chaos are predominant. The only fly in the ointment as far as science is concerned is the possibility that these laws might in some circumstances be treated more like guidelines.

QUOTE The only advantage Martin's presupposition has over that of metaphysical naturalism (and the two presuppositions aren't incompatible) is that it might be possible to prove Martin's presupposition -- after all, if the ridge really is a ramp, we could go to Iapetus and discover that. I don't think there is any way to prove the presupposition of metaphysical naturalism, however. UNQUOTE

Universals of any kind are difficult if not impossible to prove, and that goes for my presupposition as much as it does for yours. Even if it is shown that the ridge is a ramp constructed by intelligent beings as a means of exporting raw materials from Iapetus, that's just one instance. It would suggest that intelligence is more pervasive than commonly supposed, but it wouldn't prove that it has arisen at more than two locations.

QUOTE But, if one believes that design and purpose pervade the universe, where does one draw the line between purpose and nonpurpose? The Polish writer Stanislav Lem, in a novel, proposed that the expansion of the universe was being engineered and fine-tuned by alien intelligences. Is that possible? How could such a proposition be falsified? UNQUOTE

It's only possible if the universe is, in fact, expanding.

I'd need to know more details of the proposal to say how it might be falsified. As stated above, it is unfalsifiable because it is just too vague.

If the phrase "alien intelligences" is intended to imply physical beings which have physical locations and which manipulate the universe according to established physical laws, then it is hard to see how they could operate on a universal scale without at least a few smaller-scale signs of their presence - Dyson spheres, modulation of the light output of some stars or even galaxies, exit ramps on moonlets, asteroid belts where planets used to be, that sort of thing.

If on the other hand these intelligences are able to manipulate the universe without requiring any visible means of support, then the best we can do is to try to determine what their purpose might be; why they chose one particular rate of expansion rather than another. Then, having guessed at their purpose, we can try to work out what other consequences this purpose might have e.g. for other established physical constants such as the speed of light, and then see if the actual values of these constants support or contradict the assumption of intelligent fine-tuning. But this is very hypothetical, and I doubt that you could really deduce the existence or non-existence of manipulative intelligences from nothing more than the values of a few constants.

If the intelligences manipulate the universe for fun, or because they can, or for other reasons which we cannot fathom, and they do it using means which we cannot detect, then this takes us beyond the range of science, and into the realm of Star Trek.

Yeesh....what could have been a great thread....

.... still could be. But it's up to you, or anyone else who thinks that the ridge might be a decayed ring, to deal with any criticisms of that theory that might be advanced. Vague sniping from the sidelines about the quality of other contributions is not enough.

When I put forward the "ramp" theory, it was because, as I explained, a complete unbroken equatorial ridge ought to have been visible on earlier images. I had searched through a lot of images, using google, without finding anything. The latest images are of the dark, matt, low-albedo side of Iapetus. A ridge traversing the shinier high-albedo side ought to stick out like a 20 km-high sore thumb, even at the lower resolution of previous images; especially if it is a ridge of dark matt material which would contrast sharply with its lighter surroundings.

But now I've searched further, and I've found images which seem to show a ridge on the lighter-coloured side of Iapetus, e.g.

and consequently I'm more inclined to accept the decayed ring theory now. But why do I always have to find all the evidence, not just for my own theories, but for all the competing theories too?

Oups..
I withdraw my claims in reply 10 - here is the story I once read, that must have settled slightly edited in my memory...

'In Arthur C. Clarke 's novel 2001: A Space Odyssey ( 1968 ), astronaut Dave Bowman finds an enigmatic alien monolith waiting for him on Iapetus. A vast black circle hasbeen painted on the moon's surface, with the monolith occupying a smaller white circle at the centre. Remarkably, when the Voyager space probes arrived at Iapetus eighteen years later, theydid indeed photograph an enormous, roughly circular black region with a whiter region within it. Clarke reports that Carl Sagan , who was on the Voyager imaging team, sent him a photo, with the note'Thinking of you...'

source

I still subscribe to the ring hypothesis.

We haven't found a monolith on the moon.. yet. But it will happen. Oh yes. It will happen.

Interesting how folks respond to something so strange. We've seen so many images of planets and moons, but THIS is unique.

I'd be as happy as anyone if the ridges/channel contained evidence of having been mined out by some sort of intelligent-style creature or other.. until we get a closer look, who knows.

Based on everything else I've ever seen I'd go for the 'Iapetus got hit by something very large, splitting it and sending dark material all over the place' - which sadly is not as fundamentally exciting as alien mines or launch ramps or big ice cream parties..