Hi , Charon ! What ’s that ? You ’re jealous that Plutobroke the mastermind of geophysicistsworldwide yesterday , and need attention ? Fine , let ’s see what you look like up close ! Beautiful crater , lovely fluent plains , a few nerveless linear features … Wait a minute , is that a lot in a moat ? How did you create that ? !
After impressing us yesterday witha gorgeous full - magnetic disk view of Pluto ’s large Sun Myung Moon Charon , the New Horizons ballistic capsule send home an amazing high - resoluteness frame look at a small segment of the surface in resplendent 380 beat per pixel ( 1,200 feet per picture element ) resolution . Taken just 79,000 kilometer ( 49,000 stat mi ) about 1.5 hours before the stuffy approach on July 14th , the belt covers an area some 390 kilometers ( 240 miles ) long . This is the high - resolve look we ’ll get at the moon ’s surface during initial downlinks .
And it ’s making my head hurt in the best possible way .
Geoscience is at its heart a very straightforward science . The first stage of exploring a raw world is simple : await at it . Look at it from far away to get the liberal picture , and in as much point as you may manage to spot all its piffling queerness . Later , we’ll add in spectrographsto check out chemical substance distribution in the surface and the atmosphere , temperature , pressure , and even alien things like how plasma and gamy energy particles are interact with the worlds . But for now , we use what we can see in the optical spectrum to practice the all right artistic production of morphology , trying to understand how the features and landforms were created on this massive moon .
Charon at approximately 380 meters per pixel resolution , go around so that north is to the left . Image credit : NASA / JHUAPL / SwRI
When I see a pic like this , the first matter I do is attempt to match up the landforms I see with other , similar landforms I ’ve observed in the past tense . Sometimes it ’s easygoing — as a lifelong occupant of the west coast , I can spot a fault trace without falter . Other time it ’s like a geomorphic game of Concentration as I contend to call in where I once see a similar feature alien to my local terrain . Gazing at this first close look at Charon , I ’m flipping through my inventory of every other synodic month I ’ve find out photograph of , trying to remember the features carved in ancient rock and fluid ice rink .
For years , Charon was a fuzzy lump blurring Pluto ’s spherical lines in any observation we made . Last week , we amaze our first spirit at the surface , andI trace it as probably clean leaden and boring . A few days later , we saw our first traces of geology . Yesterday , I gleefully apologized for being wrong while oohing over colossal canyons . And today , I ’m reassure by conversant Crater and wholly confused by a pot ringed by a moat .
First , we need to get all the non - geology out of the style :
Processing Artifacts : The beautiful , lossless image is aboard New Horizons , we only got the compressed interpretation back here on Earth ( for now ! ) . The result is a strangely pixelated terrain , where what are otherwise smooth temporary hookup of the plain have a faint blocky overlayer . disregard it .
Lighting : This photograph was snap along the terminator , the boundary between day and night on the Sun Myung Moon ’s open . That ’s splendid because the low slant of incidence enhances shadow and throw the surface into gamey relief , but it also means the distinct modification in ignition across the scene is due to shading , not changes in albedo . ( change in albedo would mean very unlike Earth’s surface materials : shiny ice-skating rink is more reflective than dim rock and roll . )
Now , on to the fun bit : morphology ! Notice the highly technological annotations . It look silly , but the first step of understanding what ’s going on is to describe what ’s in reality there . After that comes interpretation , and if I ’ve learned anything from the New Horizons flyby so far is that whatever I interpretations I make will belike be proven wrong in the next few days .
Extremely preliminary descriptive note for the geomorphology on Charon .
proportional age : In geology , we use a series of stratographic principals to lay down a relative timeline of event . Some of those rules are that the oldest affair are on the bottom ( material exposed in volcanic crater walls is older than the surface ) , and that a matter needs to survive before anything can pass to it ( the knit stitch are older than the craters , even if parts of it have been subsequently resurface ) . One particularly interesting chip is the superposition principle of crater and crack in the northwest : which came first , the go or the crater ? For now the imagination artifact are obscuring matter , but that petite puzzle should be solved as the uncompressed images are render later .
Plains : The most basic feature film is a relatively unruffled plain , broken with occasional craters and hills . It ’s fair unvarying with no immediately distinguishable part of drastically unlike terrain , although matter are look decidedly more lumpy to at the northerly edge of the shot .
ball : Lumpy thing can be either erosional features like pitcher’s mound of carve basic principle ( seam ice ) or depositional feature like stack of sediment . stuff can be eat at or deposited by liquid ( could Charon have a history of rivers of nitrogen or Ne ? ) or gun ( could Charon have an atmospheric state , at least part - fourth dimension ? ) , or this could be the well - keep relic of some ancient surface disruption . TBD .
volcanic crater : Unlike the shockingly - tranquil first peek at Pluto yesterday , Charon ’s control surface is reassuringly cratered . The volcanic crater count still look a bit depressed compare to our own moonshine , but that ’s really not too surprising . Because Charon and Pluto are tidally lock in , the same side face each other all the time and are a spot more protect from shock events .
The craters are very crisp with unploughed rim , suggesting that they might be relatively young . mate with such beautifully smoothed plain and the relatively small number , I ’m wondering if we might regain evidence of comparatively late resurfacing on Charon .
I ’m not seeing ejecta — fabric shed out of the Crater at the time of impact . One of the crater looks like it might be complex with a key peak , a relic from a particularly eminent - impact issue .
result : The distinctive bullseye crater from the 2.3 klick / pixel result image is a good exemplar of a complex crater with ejecta ray .
crack : Long , snaky things are always fun . These are n’t particularly running , so they ’re probably not tectonic in pedigree . They could still be faults from humble , non - ball-shaped activities . At least one bent follows the classifiable Y - shape of things menstruate downhill , so could be old river bed , or collapsed tube from cryovolcanism . I can almost suppose some of them work pentagons , the classic cool down - crack practice . If it is , that could meditate some form of caloric contraction .
Over on the Planetary Society , Emily Lakdawalla is letting her inner geologist show by target out that the crevice reminded her of the Rima Hyginus region on our own synodic month , where a flood of lava cool , shrank , and fractured . It even has a crater - crack superposition duet of its own ! It ’s potential these feature on Charon imprint the same way , but with smooth ice from instead of lava .
Left : Lakdawalla indicate out that Rima Hyginus on Earth ’s moon is looking suspiciously similar ; did the features on Charon organize the same way ?
? ? ? : Here ’s the second where I accept I have no idea what ’s going on . We have some form of mountain that ’s on the order of 20 kilometer wide sitting in a ditch that ’s just about twice as wide .
A individual spiky mickle sitting by itself normally screams volcano to me , and if Pluto ’s going to be a geologically active populace through yet - to0 - be - set ways , it ’s plausible Charon could theoretically be sway some form of cryovolcanism . It does n’t look all that volcano - y to me , but with all the shadow and imaging artifacts , it could be .
But that does n’t explain why it ’s sit in a very clear indentation in the open , with a distinct fosse around it . It almost looks like the whole thing sink , except I ’m not ( yet ) check anything that indicate the champaign were ever gooey enough to be that ductile . It ’s a challenge to come up with a appendage that will hot up an icy surface enough to turn without actually meld it totally — it ’ll be fascinating to feel out what type of chemical mix is going on .
At least I ’m in good company with my delighted confusedness — the Geology and Geophysics lead Jeff Moore is quoted in the related to effigy feature saying :
The most intriguing feature of speech is a large mountain sit in a moat . This is a feature that has geologist daze and mix up .
Whatever this feature is , it ’s uncanny , it ’s wonderful , andI just know it ’s going to get an awesome name . The only reason I ’m not thresh harder is thatgeomorphology is used to being confusedabout howeven common landforms happen , so see something raw and weird is almost par for the line .
But what is it ?
I have no idea .
Top image : Charon visualise from 79,000 kilometer by on July 14 , 2015 . Credit : NASA / JHUAPL / SwRI
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