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View Full Version : Are Saturn's moons younger than the dinosaurs?



m1omg
2017-Nov-30, 04:48 PM
In a discussion about possible life on Enceladus on Reddit, I found a person arguing it couldn't have arisen yet even if it has the right conditions for it as it is just 100 million years old. Curious, never hearing of this before, I decided to search and found a lot of news pages like this http://www.astronomy.com/news/2016/03/moons-of-saturn-may-be-younger-than-the-dinosaurs as well as a passing reference to this hypothesis on Wikipedia. How likely is it that the inner moons of Saturn were formed just 100 million years ago? Is this the scientific consensus now? I admit I don't like this hypothesis one bit, it seems to be a quick and dirty explanation of Rheas anomalous movement and Enceladus's geothermal activity with "well, they formed yesterday!" and completely ignoring the fact that apart from Titan and Enceladus all the moons are pretty much saturated with craters, but I admit I have never read the paper, I am not saying the scientists that put it forward are hacks, I am merely annoyed that pop science and redditors present it as the current scientific consensus. I have seen the crater counting objection written on the internet as it evidently occured in the minds of many, but the usual responses were that cratered bodies look the same regardless if the cratering happened 100 years ago or 4 billion years ago (which is obviously wrong, old Moon craters look differently to young ones [just compare say Tycho, formed 108 million years ago, to some random far side craters] and old craters on icy bodies are often collapsed or eroded by ice slumping). I don't think cratering caused by Saturn's ring fragments during moon formation would look the same as LHB cratering.

What is the opinion of the people of CosmoQuest and the general scientific consensus. I am not a scientist, and a lot of my feelings on the theory comes from "gut feeling", but most Saturnian moons look ancient to me, battered and cratered to oblivion, apart from Titan and Enceladus. Looking at high resolution Rhea pictures like this one https://photojournal.jpl.nasa.gov/jpeg/PIA19057.jpg not one bit of the surface is untouched by craters, not one bit, it makes Callisto look young to me. Also, wouldn't Titan have some rather young and uneroded craters present if the inner moons were being formed and bombarded just 100 million years ago?

Eclogite
2017-Dec-01, 12:12 AM
A draft of the research paper is available here. (http://iopscience.iop.org/article/10.3847/0004-637X/820/2/97/pdf)

m1omg
2017-Dec-01, 11:40 AM
A draft of the research paper is available here. (http://iopscience.iop.org/article/10.3847/0004-637X/820/2/97/pdf)

Thanks. I skimmed through it, and while they are scientists and I am not, it is not any more convincing to me than when I only read pop science articles and discussions on it. Do scientists really use web based applets (although quite interesting ones I must say) like this one mentioned there http://keith.aa.washington.edu/craterdata/scaling/index.htm to make real scientific calculations? The over reliance on "integrator" simulations of unknown to me accuracy and the fact the whole reasoning seems to be about "Why is Enceladus so active?" even through there are more mysteriously active bodies (like Pluto)... I dunno, it all seem rather dubious to me. I'd like to hear the scientific consensus on this. This whole hypothesis reminds me of catastrophism and using a web tool to "prove" the Hershel crater could result from planetocentric impactors does not explain the decidedly non youthful look of the craters.