A Doubled Ringed Basin in Mercury (2009 Oct 7)

[jerbil]

A very interesting image. Despite the comment that by chance co-central impact craters might occur, for no justifiable reason I verge towards the alternative idea that the secondary ring is the result of an upwelling resulting from the primary impact.

http://apod.nasa.gov/apod/ap091007.html

[Redbone]

I believe that the chances of it being a double impact are actually quite high. The chance of any one occurance of double, centered impacts is small, but of the millions of impacts, to find one in which there is a centered double impact, and then say that the chances that this occurance is a double is small, is a misuse of statistics.

[grainpaw]

It is plainly a smiley face created by ancient Wal-Martians.

[Ray-Optics]

It is unlikely that any particular crater would be double-drilled, but considering the number of craters observed and our penchant for finding patterns and symmetry, it is just as unlikely that we wouldn't have found this rare occurrence.
The "clue" about the smoother interior region could just be further corroboration that the central crater is younger than the outer.
Possibly even more remarkable, though, is that there is another crater in the lower-left corner of the featured interior crater - that also has a perfectly centered smaller crater.

[retypepassword]

I think the reason for the double ringed basin is the same as or similar to that for the little spikes that occur both in the center of the smaller basin on the upper right corner of the image and in the center of the relatively tiny basin above and a little to the left of the double ringed basin. I can't think of a good explanation for any of them, but here's my stab at it...

I base the following explanation on the assumption that the basins are craters created from impact by extra-planetary objects. Perhaps it's like what happens when a relatively dense solid is dropped into a body of water (bucket, calm lake, etc.): Ripples occur over the water's surface, but for some time after the moment of impact, there's a large, vertical upwelling of water before the ripples form and move away from the center of impact. Because molten rock is a lot more viscous(?) and actually solidifies after impact, bigger craters have solidified ripples and smaller ones only have the vertical upwelling?

[neufer]

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• 
  
  <<The Sun symbol (Circumpunct ☉ ) has long represented gold. This is an ancient solar symbol featuring a circle with its center marked with a dot. It is the astronomical symbol/astrological symbol for the Sun, and the ancient Egyptian sign for "sun" or "Ra" in the hieroglyphic writing system. The character for "sun" or "day" in early Chinese script was similar, but it has become square in modern script 日 (ri).>>

http://en.wikipedia.org/wiki/Monad_(symbol)

<<Monad (from Greek μονάς monas, "unit"; monos, "alone"), according to the Pythagoreans, was a term for God or the first being, or the totality of all beings, Monad being the source or the One meaning without division. For the Pythagoreans, the generation of number series was related to objects of geometry as well as cosmogony. According to Diogenes Laertius, from the monad evolved the dyad; from it numbers; from numbers, points; then lines, two-dimensional entities, three-dimensional entities, bodies, culminating in the four elements earth, water, fire and air, from which the rest of our world is built up.

According to Hippolytus, this view was inspired by the Pythagoreans, who called the first thing that came into existence the Monad, which begat the dyad, which begat the numbers, which begat the point, begetting lines or finiteness, etc. Pythagorean and Platonic philosophers like Plotinus and Porphyry condemned Gnosticism (see Neoplatonism and Gnosticism) for their treatment of the monad or one. The term monad was later adopted from Greek philosophy by Giordano Bruno, Leibniz (Monadology), and others.>>

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http://heritage-key.com/blogs/gen-swart ... ircumpunct[/b]-ra-or-circle-dot-middle

Dan Brown's Lost Symbol - Circumpunct, Ra, or Circle With a Dot in the Middle?
Submitted by Gen Swart on Mon, 09/28/2009 - 16:54

<<As any true seeker of ancient wisdom knows, it ain't found in a Dan Brown novel. This is despite the bold claim in the preface to his latest epic, The Lost Symbol:

"FACT: In 1991, a document was locked in the safe of the director of the CIA. The document is still there today. Its cryptic text includes references to an ancient portal and an unknown location underground. The document also contains the phrase 'It's buried out there somewhere.'

"All organizations in this novel exist, including the Freemasons, the Invisible College, the Office of Security, the SMSC, and the Institute of Noetic Sciences.

"All rituals, science, artwork, and monuments in this novel are real."

Brown was asking for it, wasn't he? All over the world, people are now having a ball proving The Da Vinci Code author wrong again on numerous points, from his definition of ancient (200 years, duh!) to his grasp of Washington DC's geography. The Freemasons have even set up a website to fight the lies, although they are more likely to find themselves inundated with applications for membership.

But – despite Brown's leaden, explanation-heavy denouement – much confusion still surrounds the Lost Symbol itself.

Staggering through all 509 pages (spare yourself the misery, try instead the Guardian's parody) reveals the tatttoed maniacal villain was not actually hunting for the lost symbol but the lost word – and, for all good Christians, a simple capital W would have cleared the whole thing up from page 1. Besides, the Lost Symbol was never really lost. Its meaning may have been a little obscure but that's because it has multiple interpretations. Clear as mud? Excellent. Let's proceed.

The symbol in question is what Dan Brown calls a Circumpunct. Interestingly, a Google search for the word "Circumpunct" turns up only 1480 results (although that is increasing as Brown-noses unthinkingly adopt the word). It appears in no sensible dictionary, such as the OED, or even dictionary.com. In fact, some of its few web pages feature a discussion in the Wikimedia Commons on Circumpunct's validity and origins – in the ancient year of, er, 1992. The word, some argue, was first coined by the Brianists, followers of 'Brian the Cyber Prophet', a decidedly dodgy, short-lived religion of the 1990s that adopted the Circumpunct as its symbol.

Brown has this to say in his novel: "In the idiom of symbology, there was one symbol that reigned supreme above all others. The oldest and most universal, this symbol fused all the ancient traditions in a single solitary image that represented the illumination of the Egyptian sun god, the triumph of alchemical gold, the wisdom of the Philosopher's Stone, the purity of the Rosicrucian Rose, the moment of Creation, the All, the dominance of the astrological sun, and even the ominscient all-seeing eye that hovered atop the unfinished pyramid. The Circumpunct. The symbol of the Source. The origin of all things."

The Lost Symbol's cardboard cut-out hero – Robert Langdon, a professor so wacky and adventurous he refuses to wear ties (look out, Indiana!) – describes the Circumpunct as one of the most widely used symbols in history. It has dozens of meanings; in ancient Egypt, he says, it was the symbol for the sun god Ra.

Can we Trust Brown on This?

There are already conspiracy theories surrounding his usage of the symbol (including one incoherently excited site that believes the Freemasons' Circumpunct celebrates the same star pictured in a 3500-year-old Egyptian tomb, an assertion that ends up being little more than an advertisement and request for cash).

It is true that the Circumpunct symbol has been around for millennia, albeit more often known as "the circle with the dot in the middle". It can symbolise everything from gold in alchemy to a European road sign for city centre. It is commonly used as a solar symbol and reputable sources date this to ancient Egypt, where the symbol has its origins in Ra (or Re), god of the midday sun. In fact, the circle with a midpoint, plus a vertical line is the hieroglyph meaning "sun".

So how did an Egyptian symbol rise to shine again as a token of the ancient mysteries among 21st-century Freemasons in Brown's novel? Langdon's exposition is as follows: "The pyramid builders of Egypt are the forerunners of the modern stonemasons, and the pyramid, along with Egyptian themes, is very common in Masonic symbolism." Very neat. Well done, Brown.

Later in the novel, after the Circumpunct is discovered inside the stone box which housed the capstone for a mysterious Masonic pyramid, Langdon briefly mentions one of the most famous images supposedly deriving from the Circumpunct – the all-seeing eye over the Great Seal of a United States dollar bill. But mostly the Circumpunct is represented in the book in its purest, original form.

This simple symbol has many meanings, often spiritual. The Stanford Solar Center says the circle with a point is the common astrological and now astronomical symbol for the Sun, as well as the ancient alchemical symbol for gold, the perfect metal. This is because the sphere is a perfect shape, representing wholeness, oneness, unity and spirituality.

In her book Life Symbols as Related to Sex Symbolism, Elizabeth E. Goldsmith writes that the dot within the circle dates to ancient times and may have typified the seed within the egg. "This is the 'Orphic egg', a symbol of the universe whose yolk in the middle of a liquid surrounded an encompassing vault, represented the globe of the sun floating in ether and surrounded by the vault of heaven," she writes. How apt then that Ra – worshipped as the great father who created gods and men – should be represented by this symbol.

In Hinduism the midpoint in the circle is called a "bindu" – meaning point or dot – and it's said to signify the spark of male life, the point at which creation begins within the cosmic womb and one becomes many. According to the book Yantra: The Tantric Symbol Of Cosmic Unity the bindu is the "the sacred symbol of the cosmos in its unmanifested state".

It would be interesting to find out where this symbol appears all over the world. In Freemasons' halls, we now know. In the writings of the ancient Egyptians. But where else? >>

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[BMAONE23]

Something I noticed in the inner ring, It isn't circular. The inner ring is flat on one side. Might this be caused by the shape of the impactor?

[apodman]

Something I noticed in the inner ring, It isn't circular. The inner ring is flat on one side. Might this be caused by the shape of the impactor?

AFAIK, impactors of all shapes make pretty much circular craters. So I'm thinking that maybe prior to the second impact (if indeed there were two impacts) the planet contained denser material on the flattened side of the inner crater that provided more resistance than the other side to the wave in the crust caused by the impact.

[neufer]

Something I noticed in the inner ring, It isn't circular. The inner ring is flat on one side. Might this be caused by the shape of the impactor?

AFAIK, impactors of all shapes make pretty much circular craters. So I'm thinking that maybe prior to the second impact (if indeed there were two impacts) the planet contained denser material on the flattened side of the inner crater that provided more resistance than the other side to the wave in the crust caused by the impact.

Out of round crates are the result of true secondary impacts:

<<Saturn's ragged moon Rhea shows craters so old they no longer appear round
– their edges have become compromised by more recent cratering.>>

• Large (100 < D < 350 km) craters are often
  double-ringed (from prolonged splashing?) with
  
  1) the inner ring often quite out of round
  2) the outer ring often polygonal:

--------------------------------------------
Impact craters on Venus
http://www.athenapub.com/venus1.htm


http://astrogeology.usgs.gov/Projects/V ... rtype.html
--------------------------------------------
Tethys : Odysseus

------------------------------
Mercury : Vivaldi
http://messenger.jhuapl.edu/gallery/sci ... age_id=219
....................................


<<Numerous double-ringed craters may be seen on mercury. The crater Bach appears in the south polar regions of the planet, along with several others. The double-ring structures are not as prominent on the better-known near side of the Moon, but quite a few may be found on the farside as well as polar regions. It seems plausible that this particular structure was obscured or obliterated by the extensive flooding on the lunar near side.>>

http://www.astro.lsa.umich.edu/~cowley/intro2.html

Moon : Mare Orientale


Craters on the Moon pass through a sequence of typical shapes that depends approximately on their sizes (diameters, D):

* D < 20 km: craters are basically bowl shaped. This is true of both lunar and terrestrial explosion craters.
* 20 < D < 100 km: craters show central peaks.
* 100 < D < 350 km: double-ring structures.
* D > 400 km: multi-ring basins.
------------------------------
Chicxulub





http://www.lpi.usra.edu/science/kring/e ... _hires.jpg
-----------------------------------

[Lachoneus]

While I like the apparent theory of multi-ringed basins presented above, has anyone ever done a probabilistic calculation to determine the likelihood of "concentric" rings?

However, I couldn't help but wonder about the article's mentioning that double rings are rare and that the region between the two rings is more rough than the region inside the central crater.

Has anyone put these two facts together to suspect that this is just an exhibition of the "law of very large numbers?" In essence, there is a likelihood (small) of two rings being approximately concentric as a result of two objects hitting the planet in roughly the same place, where the smaller of the two objects impacts second, creating a smaller crater than the first. Add to that the fact that the distribution of larger versus smaller objects in the solar system has been declining (there are relatively more small objects now perhaps creating, on average, smaller craters than in the past), and the "anomaly" of double-ringed craters may not be as anomalous as originally thought after scouring thousands and thousands of large craters across the solar system! In fact, it may just follow standard probabilistic theory.

My question is, has anyone ever taken a sample of craters (say, from Mercury) and decomposed them taking into account decay/erosion rates?

Effectively, the likelihood is Pr(Large Object Hits)*Pr(Smaller, but big enough Object hits in the same spot|Large Object Hit Before). Frankly, this conditional statement seems to suggest the unlikeliness of random hits since you need a Large Object preceding a Small Object that has to hit in a close enough region that it looks like the same center. However, the differing smoothness conditions of the inside of the smaller crater versus the ring aren't obvious under the multi-ringed basin hypothesis...

Interesting question.

[jerbil]

Perhaps the best way to analyze the "co-central by accident" versus the "another reason" argument for the phenomenon described in the original post, is to look at other examples, on the Moon or Mercury or Mars for that matter, in which a larger crater circumscribes a smaller crater which is clearly not concentric.

[tim]

What would be the odds of a double impact from an object torn in two prior to hitting Mercury? I'm thinking of the comet Shoemaker-Levy that hit Jupiter a few years back. It passed within the Roche limit of Jupiter and got shredded. Then, it came back around and made a string of strikes. However, due to Jupiter's rotation, the strikes were in different places.

If a comet broke up passing too close to an outer planet would the trajectories of the fragments stay similar enough to hit Mercury like this? Since Mercury doesn't rotate (to my understanding), the hit would be in the same place.

[Chris Peterson]

What would be the odds of a double impact from an object torn in two prior to hitting Mercury? I'm thinking of the comet Shoemaker-Levy that hit Jupiter a few years back. It passed within the Roche limit of Jupiter and got shredded. Then, it came back around and made a string of strikes. However, due to Jupiter's rotation, the strikes were in different places.

If a comet broke up passing too close to an outer planet would the trajectories of the fragments stay similar enough to hit Mercury like this? Since Mercury doesn't rotate (to my understanding), the hit would be in the same place.

Mercury, like all the planets and all their moons, does rotate. A body that is split into multiple parts will almost certainly produce some kind of chain of craters, assuming the pieces are close enough together. If the pieces are a bit further apart, most will fail to impact completely.

[astrolabe]

Hello All,

I does appear that the central region is higher than the area between the rings.

[neufer]

What would be the odds of a double impact from an object torn in two prior to hitting Mercury? I'm thinking of the comet Shoemaker-Levy that hit Jupiter a few years back. It passed within the Roche limit of Jupiter and got shredded. Then, it came back around and made a string of strikes. However, due to Jupiter's rotation, the strikes were in different places.

If a comet broke up passing too close to an outer planet would the trajectories of the fragments stay similar enough to hit Mercury like this? Since Mercury doesn't rotate (to my understanding), the hit would be in the same place.

Mercury, like all the planets and all their moons, does rotate. A body that is split into multiple parts will almost certainly produce some kind of chain of craters, assuming the pieces are close enough together. If the pieces are a bit further apart, most will fail to impact completely.

Mercury's rotational velocity (of ~ 10 km/hr) is completely negligible compared to its orbital velocity (of ~ 172,000 km/hr).

If one of Shoemaker-Levy pieces had hit Mercury all the other pieces most likely would have missed Mercury altogether.

[Storm_norm]

is it just me or do all crater pics have the same monotone colorish feel to them?
I mean, we get breathtaking colors in nebulas... we get colorful pics of saturn's rings, jupiter's red spot, etc...
take a pic of a crater and we get, yep, black and white ??
reason for this?

[bystander]

is it just me or do all crater pics have the same monotone colorish feel to them?
I mean, we get breathtaking colors in nebulas... we get colorful pics of saturn's rings, jupiter's red spot, etc...
take a pic of a crater and we get, yep, black and white ??
reason for this?

http://apod.nasa.gov/apod/ap060907.html
http://apod.nasa.gov/apod/ap060216.html
http://apod.nasa.gov/apod/ap020316.html

[Chris Peterson]

Mercury's rotational velocity (of ~ 10 km/hr) is completely negligible compared to its orbital velocity (of ~ 172,000 km/hr).

If one of Shoemaker-Levy pieces had hit Mercury all the other pieces most likely would have missed Mercury altogether.

SL-9 was in orbit around Jupiter, not the Sun, which is why all the pieces hit that planet. However, it is extremely unlikely a similar thing would happen with Mercury.

[JohnD]

As neufer points out, and this NASA webpage confirms, "Double ring craters are common features on Mercury."
http://www.nasaimages.org/luna/servlet/ ... ng-Craters
(It's No.1 on the Google list for "double ring craters" - look and ye shall find)

A statistical freak cannot be common.
And applying Occam's razor, this is due to slumping of the initial splash, that normally leads to a central peak. In these cases the slump is arrested, presumably by the nature of differing minerals impacted and the size of the impact.

See also http://arjournals.annualreviews.org/doi ... h.27.1.385.
"Large craters collapse more spectacularly, giving rise to central peaks, wall terraces, and internal rings in still larger craters"

Simples!

John

[jerbil]

I understand JohnD's reply. If anyone thinks that the "concentric Ring" phenomenon is due to accidental double impacts, then where are they? Perhaps Chris Peterson may be able to provide us with astronomical photographs of double ring systems in which it is quite clear that two separate impacts must be responsible. By which I mean that the two impacts are definitely not at the same place.

[JohnD]

Sorry, meant to be clearer.
To use Occam's Razor means that you strike out any except the simplest theory.
Theory of central peaks is that the raised crater rim slumps down. Any material that moves inwards pushes the base of the crater further inwards. Pressure from all around raises central material into a peak.
The formation of a "complex" crater depends mainly in surface gravity. On Earth, complex craters form if it is initially more than 2-4kilometers wide, on the Moon 15-20k. I presume that variations in the viscosity of the molten material or how quickly it cools will influence the transition from a simple to a complex crater too. Surface gravity on Mercury is .38g (Moon .16g) so craters intermediate in size may become complex.
Applying Occam, why argue for an extraordinary circumstance like a double strike, precisely on target, when the accepted theory can explain double rings? Sure, a double strike could happen, but that would show up rarely, and double rings are common. Even on Earth!
See: http://thelivingmoon.com/43ancients/02f ... es_08.html

John

[neufer]

Sorry, meant to be clearer.
To use Occam's Razor means that you strike out any except the simplest theory.
Theory of central peaks is that the raised crater rim slumps down. Ant material that moves inwards pushes the base of the cater further inwards, to form a peak. If the impact is large, if the molten material is stickier or it cools quickly, then it won't make a peak, just a raised rim within the crater.
Why argue for an extraordinary circumstance like a double strike, precisely on target, when the accepted theory can explain double rings? Sure, a double strike could happen, but that would show up rarely, and double rings are common. Even on Earth!
See: http://thelivingmoon.com/43ancients/02f ... es_08.html

-----------------------------------
Well said, John; but "ant material?"
(I'll have to discuss that with the 'Grand Lunar' )

[JohnD]

nuefer,
Do you always spell check all your posts?
For every single typo?
Or were you a sub-editor in a previous life?


I had info to add to my post above, noted that typo, and thought, "I can't be *rs*d".
But I did, just for you.

John

[drr]

I believe these double ringed features could be caused by a double strike. Most likely a fragmented comet like Levy-Shoemaker 9. The rarity of these is due to the fact that the trajectory would need to be essentially straight in, which should be very uncommon, but not impossible. The smoothness of the inner base would be expected because the first strike has softened the material before the second impact. Would there still be sufficient solidity of the material to cause a second impact feature if the second impact occurred soon after the first?

--Dan

[JohnD]

dan,
Read my words, or rather those of NASA (see above).
"Double ring craters are common features on Mercury."
And often see elsewhere

That's "common". Means there are lots of them, that they are not rare.

And "fragmented comet". That occurs when tidal forces are stronger than those that keep a comet intact, and pull it into a string of fragments. As the tidal force will act radially to the major body, the fragments will orbit at slightly different altitudes, so that a fragmented comet in a descending orbit will impact in a series of craters, forming a crater chain, less common but frequently seen in evidence of the intensity of previous bombardments.
You could suggest that a fragmented comet is then captured by another body, to which its orbit is vertical. I can't do the mechanics, but how could such exquisite accuracy be repeated so often, without impacts that are intermediate between crater chains and double ringed craters?
We don't see those, do we?

John