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Scientists may have finally come up with an account for one of the Apollo program ’s most enduring mysteries : why some of the rocks bring back from the lunar aerofoil appear to have been formed inside amagnetic fieldas strong as that onEarth .
Magnetic battlefield are produced inside planetary bodies by the churning crusade of material in planets ’ electrically conductive liquefied cores . But today the inside of the non - magneticmoonis quite different from Earth ’s magnetized viscera — it ’s dense and mostly glacial , contain only a small outer nucleus region that is fluid and liquified . Scientists believe that the moon ’s inside cooled jolly quickly and equally after it formed around 4.5 billion years ago , intend it does n’t have a unassailable magnetized arena — and many scientists conceive it never did .
Apollo 17 astronaut Jack Schmitt uses a rake on the surface of the moon.
How then , could some of the 3 billion - year - quondam rock and roll retrieve duringNASA ’s 1968 - to-1972 Apollo military mission look like they were made inside a geomagnetic area powerful enough to rival Earth ’s , while others had just any magnetic signatures at all ?
Related:5 unusual , cool thing we ’ve recently learned About the moon
" Everything that we ’ve thought about how magnetic playing field are generated by planetary cores tells us that a body of the synodic month ’s size should not be capable to return a field that ’s as potent as Earth ’s , " Alexander Evans , a planetary scientist at Brown University , tell in a statement .
Scientists have number up with a raft of potential explanation over the last 50 class for this weird discrepancy . Perhaps , after its formation , the moon did n’t freeze over as fast as first thought ; or possibly the lunar month ’s gravitational interaction with Earth gave it an overstated wobble , splash around its cooling insides to encourage its magnetic field . Another idea is thatasteroidsbombarded the moon so much , the saccade kickstarted the lunar sum into spasmodic natural process .
Now , Evans and his co - author Sonia Tikoo - Schantz , a geophysicist at Stanford University , have come up with a brand raw explanation , published Jan. 13 in the journalNature Astronomy .
" Instead of thinking about how to power a stiff magnetised field unendingly over billions of years , perhaps there ’s a way to get a high-pitched - intensity theater intermittently , " Evans said .
During the first few billion years of the moonshine ’s liveliness , long before most of it froze at bottom to leave only a smallironinner core surrounded by a partially liquefied outer core , our orbital fellow traveler was an ocean of molten rock . significantly , however , the lunation ’s core was n’t importantly hotter than the drapery above it , meaning that very piffling convection between the two hap . The fact that the synodic month ’s liquefied contents could n’t churn inside it meant that it could n’t have had a steadfast magnetized battlefield like Earth ’s .
But the researcher say the moon could have make a strong intermittent field . As the moon cool down over time , the mineral bear inside its hot magma would have cooled at different rates . The densest of the minerals — olivine and pyroxene — would have chill and sink first , and the less dense magma , containingtitaniumalongside heat - producing elements likepotassium , thoriumanduranium , would have risen to just beneath the Earth’s crust and lost their heat afterward on . After cooling to the pointedness of crystallization , the titanium - load rock candy would be heavier than many of the solids below it , causing it to subside slowly but inexorably toward the liquefied out core .
— How many human could the moon support ?
— How much trash is on the moonshine ?
— How long would it take to walk around the lunar month ?
By studying the have it away piece of the moonlight and making a calculate guess on its past mantle viscousness — or how easily its magma could boil — the scientists estimated that the lunar month ’s sink Ti would have broken into chunk as modest as 37 sea mile ( 60 kilometers ) across and sunk at various rate over the path of rough a billion years . Each time one of these cold titanium clump attain the moon ’s spicy outer core , the temperature difference would have reignite the sum ’s dormant convection stream , in brief leap - starting the moon ’s charismatic field .
" you may think of it a trivial bit like a drop of water hitting a hot frying pan , " Evans said . " You have something really cold-blooded that reach the core , and suddenly a lot of heating can flux out . That causes boil in the center to increase , which gives you these intermittently strong magnetic fields . "
If the moon ’s magnetosphere really was this inconstant , these brief bursts of magnetism would be enough to explain why unlike rock candy found on the lunation carry different magnetised signatures .
Next , the scientist say they will test Apollo ’s lunar rocks to see if this traffic pattern — a washy charismatic HUA occasionally interrupted by a gigantic line of business — can be found . If explosion of potent magnetic signatures are feel among weak magnetic signatures , it could put the mystery of the moon ’s magnetism to bed once and for all .
in the first place published on Live Science .
