From: Perry Holcomb <hpholcomb@yahoo.com>

Date: November 29, 2007 10:00:15 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Schiller

To all,

This is off subject ISFA we earthlings looking up. 

But there is a connection.

Potential impact craters closer to home are

depressions found only in the Atlantic Coastal Plain

(from Delaware south), which are called "Carolina

Bays".  Most of these have an oval shape with the

elongation in a NW/SE line.  Their sizes vary over a

fairly large range.

Scholarly studies are numerous as to their origin. One

theory is that they were caused eons ago by the

breakup of a meteor, or a "small" comet, as it went

thru the earth's atmosphere producing a number of

objects that on impact resulted in these shallow bays.

These bays are numerous with more than 250,000 (as I

remember) having been identified.

Perry

--- Tim <tjp314@pacbell.net> wrote:

Duane:

Jay Melosh has published at least one book on impact

cratering.  There

are others in the field as well, of course, but his

name comes to mind.

After the SL-9 impact on Jupiter, a colleague of

mine made a

correlation between statistics of comet breakups

around Jupiter, and

the possibilities of some of those comets being

swept up by the

satellites instead of Jupiter.  Sure enough, there

are crater chains

on Ganymede and Callisto in abundances commensurate

with their

different probabilities of sweeping up the most

comets (I think

Ganymede has more than Callisto).  These are really

cool, consisting

of dozens of distinct craters all in very long

chains, with some

ellipticals as well.

-Tim.

--- In Astro_IIDC@yahoogroups.com, "Duane"

<macastronomer@...> wrote:

I agree with that assessment. I'll throw out some

inexperienced

"thought" physics and 

make a guess that when the impactor broke apart,

the piece that

impacted first was on 

the side that was spinning forward and the other

piece spun

backwards making it lag 

behind differentiating the first impact, which was

on the left of

the image and the final 

impact which trailed immediately behind on the

right. This

interaction would mess-up the 

formation of a central peak on the left and the

one on the right

would be malformed by 

both the combination of kicked up debris from the

previous impact

(which would linger 

due to low gravity and roll over the top of the

subsequent

explosion, landing on the far 

side of the second impact and/or get blown clear)

and also due to

the lack of material on 

its predecessor's side. (note, impacts that are

slightly more

separated by distance or time 

would still meld together but have two central

peaks)

I don't know if that's how this really takes

place, but that's how

I'd picture it happening in 

my mind. Looking at the image and the mess of

mountains on the right

crater, it sure 

seems like a messed up central peak to me.

I'm probably wrong about this too, but would the

case of an oblong

impact, which you are 

correct that it requires an extremely low angle

impact, the central

peak would be still 

centralized but possibly, slightly, elongated? If

that were the

case, it wouldn't fit the 

results.

If anybody knew of a book that explained impact

physics, I sure

would be interested in 

checking it out. The Moon is much more interesting

when you can

mentally picture its 

dynamics.

--- In Astro_IIDC@yahoogroups.com, "Tim" <tjp314@>

wrote:

Hi Duane:

The problem with the suggestion that it's two

craters that overlap is

that there should be a rim between the two,

where their ejecta sheets

interacted.  Likewise, if they formed at

different times, the younger

crater's rim should extend across the line

between them.  With an

oblique impact (and they really have to be very

low angles - like less

than 5 degrees - in order to not form a circular

crater), you really

can form an elliptical crater.  I think that

those folks I know who

work on the physics of these things will say

that the appearance of

two (or more) overlapping craters is due to the

impactor breaking into

multiple pieces before impact, but not

separating by enough distance

to form two separate craters.

-Tim.

--- In Astro_IIDC@yahoogroups.com, "Duane"

<macastronomer@> wrote:

I can see how it's debatable, but with a nice

shot like this, it

sure looks like two craters to 

me. I popped that out there with a couple

circles showing what I

think clearly looks like 

two nice ovals:

http://homepage.mac.com/deal/schiller20060410_1628.jpg

--- In Astro_IIDC@yahoogroups.com, Alan

Friedman <alan@> wrote:

Hi Duane -

I think the jury is still out on the

formation of Schiller (but  

leaning towards an oblique impact):

http://www.lpod.org/index.php?s=schiller&paged=3

Looking straight down via Lunar Orbiter

images (or in earth

based  

images taken at a low sun angle) that

bizarre caldera topped

mountain  

is clearly seen as two separate features - a

long hill with a

crater  

on the floor of Schiller just behind.

Thanks,

Alan

On Nov 27, 2007, at 2:32 AM, Duane wrote:

Hi Alan,

Nice shot. It makes me eager for ver. 4

but then again I

know this  

image is from you and

part of me knows you're taking it beyond

my capability :)

I never looked at Schiller closely before,

but it appears to be

two  

craters joined (and

flooded) together creating the potato

shape, doesn't it? Maybe  

that's already known, but

then again self discovery is good too.

Thanks for sharing and keep'em coming.

Duane

.

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