Somewhat better images
than with my 8" scope.
NASA's Lunar Reconnaissance Orbiter (LRO) has captured a magnificent view (big version here) of sunrise over mountains in the centre of the Moon's Tycho crater: Sunrise over the Tycho crater's central mountains. Pic: NASA NASA explains: "A very popular target with amateur astronomers, Tycho is located at 43.37°S, 348.68°E, …
I can remember watching the Apollo expedition TV feeds as a young teenager and seeing all the magnificent stuff being discovered -- like the famous orange dirt on Apollo 17 -- and found myself sharing the astronauts' sense of wonder as they all commented on how it seemed that all this awesome stuff had been lying there for millions of years just waiting for us to find it.
I suspect LRO is shooting in grayscale.
Check out some of the orbital and surface photography from the Apollo missions; depending on the lighting and the viewing angle, the color of the Moon varies from the usual slate gray to a warm charcoal gray to a pale chocolate brown.
Any geodynamics folk out there who can explain how the central peak is formed from an impact event?
I had always presumed that the central peak was caused by a form of induced elastic compression and rebound generated by the tremendous forces in play, but the relevant Wikipedia article says otherwise:
-- -- Wikipedia: Complex crater
-- -- -- -- http://en.wikipedia.org/wiki/Complex_crater
and indicates the center cone (or cone ring, for very large impacts) are created by "a process in which a material with little or no strength attempts to return to a state of gravitational equilibrium."
Anyone care to elaborate?
I'm not a geodynamicist either, but two questions asked at the LRO blog at http://tinyurl.com/6kdavlc are:
"Were these distinctive outcrops formed as a result of crushing and deformation of the target rock as the peak grew? Or do they represent preexisting rock layers that were brought intact to the surface...?"
I also seem to recall a theory involving volcanic activity caused by a rupturing of the crust in which the crust rebounds from the impact and causes a "backsplash" of lava which hardens in place, but the LRO blog doesn't mention it.
Still in all, it's frickin' gorgeous.
"Any geodynamics folk out there who can explain how the central peak is formed from an impact event?"
Tut! Tut! Everybody know that the aliens that started intelligent life on earth left it that way after they buried the monolith, aka TMA-1, there.
Paris, "The thing's hollow - it goes on forever – and - oh my God* - it's full of stars!"
* whatever one you want
Actually, Pink Floyd were at least partially right about there being no "dark side". The term "dark side" is actually a misnomer; the proper term, as taught to me by the Apollo crewmen, was "far side" -- that is, the side that's always turned away from Earth as it's "tidally locked" in position in its orbit, even though the Moon has a rotational cycle. The far side receives sunlight on a regular basis, but we just don't see it because it's always facing away from us, so the Moon isn't really "all dark".
Sorry, Mr. Floyd.
Among my shit-ton(ne) of space-related bookmarks is the LRO site, which I check regularly. I first saw these images there a couple of days ago and damn' near crapped my drawers at their sheer awesomeness. Yesterday, I saw they were picked up by the Bad Astronomy blog, where Phil Plait was in a similar state of pants-crapping delight. I especially enjoyed the close-up of the main central peak, and the small depression where a boulder was resting. I'd never seen the Tycho peaks in such detail and in a view such as the oblique sunrise view, and it totally knocked my lights out.
No goddamn' wonder these are being blasted all over the place. They're made of awesome.
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