Shrinking Mercury

MeteorWayne · Mar 18, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>LOL wayne!!  You don't like my M.J. pic?...No? Posted by majornature</DIV>The pictures fine, It's too damn big and takes up too much space. Many here find it rather annoying.Now if you don't mind being annoying, go right ahead.... <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

derekmcd · Mar 25, 2008

Apparently she doesn't mind.  As if navigating the fora aren't difficult enough already, the extra space just adds to it. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

MeteorWayne · Mar 25, 2008

http://www.space.com/scienceastronomy/080325-st-mercury-cliffs.html "Mercury's surface is not only peppered with impact craters, but also wrinkled with mysterious chains of cliffs.Scientists think the "lobate scarp" cliffs — some 2 miles (3.2 kilometers) high and hundreds of miles long — were created as Mercury's crust bunched up around its shrinking interior, something like a dried-out piece of fruit. A new theory, however, suggests that rising sheets of hot mantle rock popped out the planet's characteristic ridges, helping to create the cliffs."There's a preferred north-south alignment to these scarps," Scott King, a planetary geophysicist at Virginia Tech University, told SPACE.com. "If you just have a shrinking sphere, there's no reason they should be aligned. It should be fairly random."Instead of just a shrinking crust, King thinks linear sheets of rock heaved on the planet's crust from below, pushing up the cliff-like features. He detailed his computer-modeled hypothesis in the March 16 online edition of the journal Nature Geoscience."Assuming the scarps are indeed lined up, King thinks a thin yet active mantle layer beneath Mercury's crust may be to blame for the cliff-like features."It has a very large iron core compared to Earth, Venus and Mars," King said of Mercury's metallic heart. "The rock above it is confined to a real thin shell."Because there's hardly any room for hot mantle rock to snake toward the planet's surface, King's models suggest that the material is forced into a rolling pattern of linear or sheet-like plumes. On Earth — where mantle space abounds beneath the crust — rising rock is mostly squeezed into cylindrical plumes."The dynamics are much different for Mercury. I've done a number of models, and this roll pattern almost always shows up," King said. "The stresses created by that on the crust can be enormous."Still active?Although both King and Solomon agree that Mercury's cliffs probably stopped forming a few billion years ago, King's models suggest that convection activity might still be roiling beneath the planet's surface. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Mar 25, 2008

Posted by MeteorWayne

Thank you very much MeteorWayne. Your post has helped validate something I had been seeking & starting to find some evidence of. Your post explains in a clear way what has been tipping me off.A while back, there was speculation that Mercury's core was contaminated by Sulphur, thus lowering the melting point of the iron. Whether or not this is true ais a little immaterial, the fact remains that Mercury's core is still active, according to evidence.One feature imaged by Mariner 10, to me is a smoking gun.Tir Planitia. Area imaged below is 130 KM across. <img src="http://sitelife.space.com/ver1.0/Content/images/store/3/2/c39d8702-52d7-4830-b281-53f5b6e015be.Medium.jpg" alt="" />What is immediately obvious, is the dark stain & the small rupes. The dark stain looks less heavily cratered than the surrounding terrain. Also if it is volcanic ash, then over time micrometeoroids will have gardened it into the regolith. Clearly this has not happened here, the dark staining is clearly visible on the surface.I reckon geologically speaking, the area pictured above was active till 'fairly recently'.Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

neilsox · Mar 30, 2008

It seems reasonable that all the planets are shrinking perhaps one part per billion per century, but we have no proof and little evidence, so they could be growing about that fast due to meteors, dust and micro comets.It is also reasonable to assume the cores are cooling , but we have no proof and little evidence. Rapid shrinking seems very improbable.  Neil

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