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Astronomers Solve Puzzle of the Mountains That Fell From Space
KentuckyFC (1144503) writes "Iapetus, Saturn's third largest moon, was first photographed by the Cassini spacecraft on 31 December 2004. The images created something of a stir. Clearly visible was a narrow, steep ridge of mountains that stretch almost halfway around the moon's equator. The question that has since puzzled astronomers is how this mountain range got there. Now evidence is mounting that this mountain range is not the result of tectonic or volcanic activity, like mountain ranges on other planets. Instead, astronomers are increasingly convinced that this mountain range fell from space. The latest evidence is a study of the shape of the mountains using 3-D images generated from Cassini data. They show that the angle of the mountainsides is close to the angle of repose, that's the greatest angle that a granular material can form before it landslides. That's not proof but it certainly consistent with this exotic formation theory. So how might this have happened?
Astronomers think that early in its life, Iapetus must have been hit by another moon, sending huge volumes of ejecta into orbit. Some of this condensed into a new moon that escaped into space. However, the rest formed an unstable ring that gradually spiraled in towards the moon, eventually depositing the material in a narrow ridge around the equator. Cassini's next encounter with Iapetus will be in 2015 which should give astronomers another chance to study the strangest mountain range in the Solar System."
Astronomers think that early in its life, Iapetus must have been hit by another moon, sending huge volumes of ejecta into orbit. Some of this condensed into a new moon that escaped into space. However, the rest formed an unstable ring that gradually spiraled in towards the moon, eventually depositing the material in a narrow ridge around the equator. Cassini's next encounter with Iapetus will be in 2015 which should give astronomers another chance to study the strangest mountain range in the Solar System."
...a collapsed ring system?
I've fallen off your lawn, and I can't get up.
"That's not proof but it certainly consistent with this exotic formation theory."
So they didn't solve the puzzle.
Iapetus has only a fraction of Earth's gravity (Iapetus radius 735 KM, Earth radius 6371 KM, you do the math, after figuring out the relative density for yourself). Wouldn't a hugely smaller gravity significantly affect the angle of repose they carry on about in that referenced scientific paper? I doubt you can compare the angle of repose of rounded particles (or snow and hail) on Earth with that of a very small _and airless!_ moon.
But I'll leave that to the astrophysicists to work out.
Erroneous. It was our space overlords running an experiment.
Does not sound like they solved it. Headline should be "Astronomers Ponder Puzzle..." perhaps?
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medium.com link. Sorry, no. Last time I decided: never again.
"Iapetus, Saturn's third largest moon, was first photographed by the Cassini spacecraft on 31 December 2004."
Really? First photographed in 2004? Didn't any of the earlier probes like Voyager take pictures of it?
I seem to remember something about strange light and dark patterns on that moon from a book i read many years ago.
I think it was written by a "distinguished but elderly scientist"
You mean, like the asteroid 1999 KW4 ? I'd say that the source of the Iapetus ridge has been pretty obvious since the Science papers on that body.
Saturn's ring material falling onto the Iapetus. This "mountain range" is technically an equatorial ridge, but as anyone who's seen an hour glass it's not hard to imagine (-- disclaimer) the same thing is happening on the moon of a planet with it's own ring system.
At 15.5 degrees to Saturn's equator doesn't seem like it's that far "off-ring" to prevent this from happening, though that Iapetus in tidally locked (that is it's rotational period is equal to it's orbital period, and so always presents the same face to Saturn, and therefore also it's direction of motion) should mean the equatorial ridge is a bit higher on Iapetus' forward-facing hemisphere (facing the direction of it's orbit), and lower on it's back-facing hemisphere. Should be fairly straight-forward, if not easy, to see if this evidence is there.
Till we see 1300km long and 10 to 10 km diameter asteroids in space, we just have to file it under, "it is the best we could do, under these circumstances".
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
OMG that medium.com site is exceptionally hard to read. giant font, 90% empty screen. Butt Ugly.
I will avoid this shit as much as possible.
"Life is short and in most cases it ends with death." Sir Sinclair
from the moon mold, obviously.
The summary seems to reflect the way 2 bodies in space interact when they pass the Roche limit and the smaller body dissolves due to tidal forces.
Since it's composed of ice something from the center, (water) ejected leaving a cavity and the 2 halves "pinched" and extruded a ridge.
"If any question why we died, Tell them because our fathers lied."
Do it again, do it again!
Table-ized A.I.
Astronomers think that early in its life, Iapetus must have been hit by another moon, sending huge volumes of ejecta into orbit. Some of this condensed into a new moon that escaped into space.
"Iapetus, Saturn's third largest moon, was first photographed by the Cassini spacecraft on 31 December 2004. The images created something of a stir. good job blossomsquare.com