The Impact And Exit Event.

[lemit]

I have a question infinitely more stupid than Modest's. Where are the antipodal indentations? Are the Atlantic and the Pacific supposed to be the entrance and exit "wounds?"

I also have a less stupid question. You cite similarities between the Mid-Atlantic Ridge and the Andes Mountains. Aren't they of vastly different ages and therefore not possibly a result of the same event?

The design of a missile sharp enough to punch through the mass of the earth and yet blunt enough to poke out an object the size of the moon could have some practical use.

This is a fascinating theory, but I just can't imagine the earth surviving that kind of structural stress and deformation. The glancing blow theory stretches both the imagination and the earth. The direct hit theory seems enough to break both.

--lemit

p.s. I didn't mean to characterize Modest's questions as stupid, just my own.

[Turtle]

Originally Posted by lemit

The glancing blow theory stretches both the imagination and the earth. The direct hit theory seems enough to break both.

--lemit

p.s. I didn't mean to characterize Modest's questions as stupid, just my own.

i have argued here on numerous occasions against the idea of a 'glancing blow', or 'bounce' of an asteroid in regard to having visual 'evidence' of such a thing by looking at a valley or some such elongate structure. the energies involved have no correlation in experience to such common proposed analogs as billiard balls or bullets.

if you may have taken time to read the entire article that i earlier linked to, you may have seen what i seen which rather took me aback as it seemed my favored preeminent expert contradicted my position by using the term 'ricochet'. to whit:

Ring World

Several studies, both theoretical and with laboratory data, suggest that some large impacts are capable of ejecting material into space in the form of debris rings, if the mechanics of the impact meet certain requirements. The authors conclude that the mostly likely scenario for ring creation is a low-angle impact by a large asteroid. Some earth materials and melted meteoric debris, called "tektites" would form the ring materials.

Boslough describes an impact where the collision object ricochets back into the atmosphere. The ricochet becomes part of an expanding vapor cloud, setting up an interaction that allows some of the debris to attain orbit velocity. The orbiting debris will collapse into a single plane by the same mechanics that led to the rings of Saturn and other planets, Boslough explains. Such a ring would most likely form near the equator, because of the dynamics involved with the moon and the earth's equatorial bulge. ...

my verbeage quibble with mark's choice of word aside, he seems to make clear here that what 'ricochets' is not an intact impactor, it is impactor material vaporized but not mixing with vaporized terrestrial material. oui/no?

[lemit]

I've mentioned elsewhere that in 1947, Kenneth Arnold, upon seeing what looked to him like a flock of geese moving erratically in the sky, the way objects in the sky seem to move when we are without frames of reference but have those involuntary movements of our heads, described that movement as "like saucers skipping across the water."

So, looks like we might have been visited by flying saucers a long time ago.

--lemit

[Moontanman]

[Turtle]

Originally Posted by lemit

I've mentioned elsewhere that in 1947, Kenneth Arnold, upon seeing what looked to him like a flock of geese moving erratically in the sky, the way objects in the sky seem to move when we are without frames of reference but have those involuntary movements of our heads, described that movement as "like saucers skipping across the water."

So, looks like we might have been visited by flying saucers a long time ago.

--lemit

i love how you ricochet lentil, and that's a fact. loving tangents as i do, i see yours and raise it a penetrating reference.

impacts, outpacts, flybys and they kin. duck & cover! more from señor boslough, impact physicist at sandia national labs.

Meteor Plumes Suggested For Cause Of Transient Dark Spots In Upper Atmos

ALBUQUERQUE, N.M. -- A Sandia National Laboratories physicist and his Texas-based research colleague have done some calculations that may offer additional insight into a decade-old astronomical controversy about whether up to 30,000 house-sized snowballs, or icy comets, are striking Earth each day.
...
Now, however, Sandia physicist Mark Boslough and Randy Gladstone of the Southwest Research Institute in San Antonio, Tex., have published a study that provides a less provocative -- but still scientifically interesting -- explanation for the so-called atmospheric holes.

They may be plumes, not holes, and meteoroids may be the source.

Their computational simulations, which make use of Sandia's shock physics code CTH and Boslough's earlier work with Sandia colleague Dave Crawford in successfully predicting the visible plumes from Comet Shoemaker-Levy 9's impact into Jupiter in 1994, suggest that the entry of ordinary meteoroids can form dark spots very similar to those reportedly
observed by the satellite instruments.

Their study is published in the Dec. 15 Geophysical Research Letters, along with four other studies by other scientists that together the journal say provide "five independent tracks of evidence that are entirely inconsistent with a huge bombardment by small comets." The journal says the five studies together "refute this [the small comets] hypothesis." ...

ps mootmanatter, when i stop laughing at your cartoon i'm going to admonish you not to not feed the monkeys.

[lemit]

Ok Moon, I realize you might be kind of protective of your view.

That is an interesting rendering of what a direct hit would look like. I had anticipated that a relatively small, high velocity projectile would be necessary. Perhaps a spinning projectile?

Do you think God owns a gun? Do you think maybe all the events described as "Entry and Exit Events" might really be some galactic target practice?

--lemit

p.s. That picture reminds me of the New Yorker cartoon caption contest. Could we do something like that?

If we can, my entry is "Oh Crap! I didn't even get the lawn chair set up!"

[Moontanman]

Originally Posted by lemit

Ok Moon, I realize you might be kind of protective of your view.

That is an interesting rendering of what a direct hit would look like. I had anticipated that a relatively small, high velocity projectile would be necessary. Perhaps a spinning projectile?

Do you think God owns a gun? Do you think maybe all the events described as "Entry and Exit Events" might really be some galactic target practice?

--lemit

p.s. That picture reminds me of the New Yorker cartoon caption contest. Could we do something like that?

If we can, my entry is "Oh Crap! I didn't even get the lawn chair set up!"

Actually I stole that pic from T-Birds Create a caption thread. I think the best caption was "Houston, you have a problem!"

[Turtle]

okaly dokaly; let's get back to the op more than less.

reposing question to fishlips: when did the supposed penetrating impact happen & how did you calculate that date?

i went to the handy dandy impact calculator and put in the maxes, i.e. 15 kilometer iron meteoroid striking earth at a 90 deg angle going 60 kilometers per second and hitting igneous rock. the calculator asks for a distance from impact as it gives effects for fire-ball, wind, etc. and i chose the maximum allowed 500 kilometers away. toast!

not sure if this link to the calculator will hold my input result page, but the crater left is only (only!!!! ) 1,877 meters deep. moreover the data output says even an iron object of this size reaches the ground in a broken condition and gives the frequency of an impact of this size at once every 3.7 billion years. total kinetic energy 2.54 x10²⁵ joules.

fun to play with though for all.

Down 2 Earth | Impact Simulator

[GAHD]

My dad has subscribed to this theory for atleast 15 years, he talked to me about t a while ago. His angle on it comes from being a rifle-nut.

His take goes like this: A extremely dense asteroid, hits the earth at about an 80-85degree angle, just enough that it ricochets off the iron core after penetrating the crust. The ricochet effect destabilizes the rotation of the core(causing the oddly angled north pole relative to true north), it also causes exiting meteorite to take a helical path outwards and collect a large portion of the lighter crust material with it while seeing the surrounding area with the diversity of heavy metals that otherwise would be closer to the core.

His example: take a hunting rifle, and shoot a fruit with a hard nut center. If the shell is dead center it will shatter the nut. If it is slightly off center it will ricochet, taking a much larger chunk out of the back than if it just passed right through and leaving the nut displaced a small amount. If it is a good portion off center it will pass right through without much damage to the fruit in question.

[freeztar]

I'd be interested on your dad's take on wave propagation and how this can be extrapolated from a fruit to a planet. (I imagined a peach, FWIW)

Rather than use a fruit with a nut center, why not try to emulate the different compositional densities of planet Earth on a relative scale? I'm not sure what materials would be appropriate for this off the top of my head, but it should be fairly easy to come up with a better model to shoot at.

Of course, Turtle is right when he pointed out that we are dealing with forces orders of magnitude outside our normal understanding.

Anybody have any links to computer model images of this sort of thing? (bonus points)