[meteorite-list] Meteorite-list Digest, Vol 85, Issue 13

From: Steve Curry <cwheileg_at_meteoritecentral.com>
Date: Wed, 8 Sep 2010 12:02:34 -0600
Message-ID: <AANLkTi=pW1eUEcdwMCWZa2MjQfNmdQFmQF3JZcBgvY6n_at_mail.gmail.com>

As to the question of when, and by whom, Lunar meteorites will be
recovered on the North American Continent, you might wish to review
the following site, and then compare this work to the Lunar &
Planetary Institute's "Lunar Sample Atlas" of those specimens returned
by the Apollo 11, 12, 14, 15, 16 & 17 astronauts. Pay particular
attention to the Anorthositic, Troctolitic, Fragmental & Feldspathic
Breccia specimens on both sides.
http://www.flickr.com/photos/53287361 at N04/sets/
    Let us know, if this solves the mystery for you.
Thanks!
Steve C.

On 9/8/10, meteorite-list-request at meteoritecentral.com
<meteorite-list-request at meteoritecentral.com> wrote:
> Send Meteorite-list mailing list submissions to
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>
> Today's Topics:
>
> 1. AD : NWA 869 for sale (Malek Youssef)
> 2. YD impact "debate" (E.P. Grondine)
> 3. Re: Witnessed fall lunars? (Sterling K. Webb)
> 4. Re: YD impact "debate" (Richard Montgomery)
> 5. Mammoth-Killer Impact Rejected, Richard A. Kerr 2010.08.30 10
> comments news.sciencemag.org: Rich Murray 2010.09.07 (Rich Murray)
> 6. ad - Vesta for sale (Edwin Thompson)
> 7. Re: Witnessed fall lunars? (Melanie Matthews)
> 8. Shielding of the Moon by earth (Rob Matson)
> 9. Re: Shielding of the Moon by earth (Melanie Matthews)
> 10. Re: Shielding of the Moon by earth (Rob Matson)
> 11. Re: Shielding of the Moon by earth (Steve Dunklee)
> 12. Re: Shielding of the Moon by earth (Martin Altmann)
> 13. Rocks from Space Picture of the Day - September 8, 2010
> (Michael Johnson)
> 14. Re: Witnessed fall lunars?still no clear answere (Steve Dunklee)
> 15. Re: Witnessed fall lunars?still no clear answere (Adam Hupe)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 7 Sep 2010 19:46:03 -0700 (PDT)
> From: Malek Youssef <scyphocrinites at yahoo.com>
> Subject: [meteorite-list] AD : NWA 869 for sale
> To: meteorite-list at meteoritecentral.com
> Message-ID: <997039.21213.qm at web53304.mail.re2.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi Listees
> Anyone interested in NWA 869 Meteorites may contact me offlist.
> Best Wishes
> Malek
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 7 Sep 2010 19:41:22 -0700 (PDT)
> From: "E.P. Grondine" <epgrondine at yahoo.com>
> Subject: [meteorite-list] YD impact "debate"
> To: meteorite-list at meteoritecentral.com
> Message-ID: <515823.50104.qm at web36902.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi Paul, all -
>
> Go to http://cosmictusk.com
>
> This "debate" is pretty much all over, though we can expect denial to
> continue for the next 30 years or so, based on our experience with the KT
> impacts. All that that denial did was to retard research for much of that
> time, and I expect that the same thing may happen with this impact.
>
> I also think this denial may have to do with the inability of some people to
> accept that impacts pose a threat, or to give up their earlier explanations
> for the observed data, or because they view research into impact as a threat
> to the funding of research more personally important to them.
>
> E.P. Grondine
> Man and Impact in the Americas
>
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 7 Sep 2010 22:32:42 -0500
> From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
> Subject: Re: [meteorite-list] Witnessed fall lunars?
> To: <meteorite-list at meteoritecentral.com>
> Cc: Rob Matson <mojave_meteorites at cox.net>
> Message-ID: <6254D5FC37F74680ABE48BE0A4DDE5A2 at ATARIENGINE2>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> Hi, Lunar Gang, and List,
>
> We have a situation here that needs straightening
> out.
>
> Escaping from the Moon is one thing. Getting
> to the Earth is another. Here's how it starts.
>
> An object is propelled off the lunar surface
> (doesn't matter how). As soon as it's no longer
> in contact with the force that impelled it, its
> speed can't increase.
>
> It can decrease, though, and it does. Lunar
> gravity will pull down on it, reducing its speed
> at the same rate it would gain if it fell. It goes
> slower and slower. Eventually, its speed will fall
> to zero and it will reverse course and start to
> fall back.
>
> UNLESS its starting velocity is above or at the
> Moon's escape velocity. It takes 2380 meters/sec
> to escape to the point 38,000 miles from the Moon's
> center to where the gravitation pull of the Earth
> and the Moon are equal. If the rock started with
> 2381 m/sec, it will get there moving at 1 m/sec,
> a crawl. After that, the important thing is: which
> way was it headed?
>
> Surrounding the Moon is a distorted spherical
> (parabolic) envelope with its "pocket" pointing
> directly at Earth that outlines that balancing
> point between the Earth's and the Moon's "pull."
> It's called the Hill Sphere (for any body). The Hill
> Sphere, or equipotential point for the Moon, is
> at a radius of about 38,000 miles, still over 200,000
> miles from earth.
>
> If a Lunar escapee has enough speed to reach the
> Moon's Hill Sphere and cross over, it will be under
> the control of the Earth's gravitational field. The
> Moon has only 1/81.3 of the mass of the Earth, so
> the balance point between them is much closer
> to the Moon than the Earth.
>
> Oh, if it was going very fast, it could escape the
> Earth too, but the odds against that are great. No,
> that rock is dam lucky to have made it to the
> Translunar Gravitational Equipotential Point for
> its flight.
>
> In general, since Lunar escape velocity is low
> compared to the Earth's, if a rock just barely escapes,
> by the time it crosses the Border, it would be moving
> very slowly, almost standing still. From the viewpoint
> of the Earth, it's like someone carried a rock 'way out
> there and while "standing still" far from Earth, dropped it.
>
> Like so many borders, once you cross it, you're in
> another jurisdiction. The Moon no longer has any
> say in what happens to the rock that crosses the
> Hill Sphere Border.
>
> Slowly at first, it begins to fall toward Earth, but it moves
> faster and faster, eventually acquiring (up to) 11,233
> meters/sec, plus any starting speed, blah, blah...
> Will it curve and swerve and head straight for the
> Earth's central spot?
>
> No, not often. There are a variety of outcomes and
> few of them will get a rock to land on Earth. Many will
> end up co-orbiting the Sun along with the Earth and
> will eventually tangle with the Big Mother Planet again.
>
> Some, that are headed more or less toward the Earth
> to begin with will scream past in an asymptotic pass,
> whipping around the Earth, changing direction and
> picking up speed, in a home grown version of the
> "gravity well" maneuver. They will tossed far and gone,
> in a gentler version of what Jupiter does to anything
> gets near it.
>
> But only if they miss...
>
> Some of those headed our way, a small percentage,
> will actually "strike" the Earth, or come in at a steep
> angle. They might survive to the ground... or they
> might not.
>
> A few, we lucky few, will graze the top of the Earth's
> atmosphere tangentially, in a flat trajectory roughly
> parallel to the surface of the planet, at about zero
> degrees of altitude (relative to us). They will be moving
> between 11,186 meters/sec and 13,466 meters/sec
> and their chances of landing are As Good As It Gets.
>
> That's the simple view from Physics 101. It turns out
> to be more complicated, however.
>
> NOW, we have to turn the question around and look
> at it from the Moon's and the Rock's perspective. If you're
> a rock looking to get the Earth, what's the best way to
> leave home? That will determine what happens to you
> in the long run.
>
> So, imagine you're an indecisive rock staring at the
> black Lunar sky... If you aim for where the Earth is
> NOW, it won't be there when you arrive. so which way
> do I go?! There are no signposts and no obvious solution...
>
> Now, it's time to introduce you to Barbara E. Shute. Her
> work can be found at the NASA Technical Reports Server:
> http://ntrs.nasa.gov/search.jsp?No=10&Ne=35&N=4294963886&Ns=ArchiveName|0&as=false
>
> I suggest "Dynamical behavior of ejecta from the moon.
> Part I - Initial conditions," a PDF of which can be found at:
> http://hdl.handle.net/2060/19660021054
>
> It's just what that rock is looking for --- a road map to
> Earth! However, this is pretty heavy lifting if your orbital
> mechanics are rusty, like mine, although no doubt Rob
> Matson will eat it up and ask for please, another bowl, sir?
>
> First, the Moon, OUR Moon, is odd. It's a long way from
> the Earth and its orbital velocity (1022 m/sec) is much
> slower than its escape velocity (2380 m/sec), so when
> a rock does escape the Moon's gravity, it's in for a wild
> ride, as it's often going too fast or too slow for where it is.
>
> First, to actually escape the Moon, the rock's speed has to
> be greater than mere escape velocity. Escape velocity will
> only get you to the Hill Sphere Border. It seems that velocities
> of 2600 to 2700 meters/sec are needed to actually escape the
> gravitational environment beyond the Moon's Hill Sphere..
>
> Second, given that you're going fast enough, the one
> critical factor is the angle at which you leave the Moon's
> surface. There is one critical angle for each spot on the
> Moon's surface that guarantees you'll get to Earth if
> your speed is right. That ideal angle for the minimum
> possible velocity varies depending on where on the
> Moon you are, but other angles will do the job if you
> are going faster.
>
> An intriguing conclusion that it is just as easy to get
> to the Earth from the "back" side as it is from the "front"
> (or facing) side. That means that all our breathless
> speculation about whether a Lunar meteorite COULD
> have come from the Backside is wasted. It makes
> NO DIFFERENCE. Each side is an equally likely
> source.
>
> However, the Eastern Hemisphere is heavily favored, and
> it seems likely that everything that makes it to the Earth
> came from the Moon's "East Coast." When the rock leaves
> the East Hemisphere, its velocity is added to the Moon's
> orbital velocity. If it's pointed right, it's on a "fast return
> trajectory" toward the Earth.
>
> But if it pops out of the Moon's gravitational control from
> the West Hemisphere, it's suddenly running too slowly
> in a retrograde orbit that can't be sustained. It makes a
> sharp right turn and crashes back into the Moon's surface
> and makes a new (smaller) crater!
>
> If Shute's math is too much for you (show of hands?), skip
> to the charts and diagrams at the end. They make things
> much clearer. Shute did numerical integrations to sample
> impacts, ejecta-producing events, and concludes that as
> much as 3.3% of the ejecta could get to Earth.
>
> Surviving the landing is another matter. (Isn't it always?)
> After reading this, it's my impression that the Moon likely
> produces much more material that arrives at the Earth
> than we usually think it does, and that the short supply
> of Lunaites is a "collection selection" effect, as has been
> suggested.
>
> Another impression is that it may only be the more
> powerful impacts that produce Lunaites. In that case,
> deliveries to the Earth may only occur at intervals and
> there may be a multitude of Lunaites delivered from
> each impact (although they may be scattered), in contrast
> to the steady rain of meteoroids from far beyond the Earth.
>
> I'm too Googled out to check, but is there "clustering"
> of the terrestrial ages of Lunaites at irregular intervals?
>
>
> Sterling K. Webb
> ---------------------------------------------------------------------------------
> ----- Original Message -----
> From: "Randy Korotev" <korotev at wustl.edu>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Tuesday, September 07, 2010 4:06 PM
> Subject: Re: [meteorite-list] Witnessed fall lunars?
>
>
>>
>>>MikeG asks:
>>
>>>"Is there a theory for why there have been no witnessed falls of lunar
>>>meteorites? It seems odd to me that we have 4 Martian witnessed falls
>>>(Shergotty, Chassigny, Zagami, Nakhla, and almost Lafayette) and no
>>>lunars."
>>
>> One issue is that these 5 meteorites are 5 kg, 4 kg, 18 kg, 10 kg, and
>> 0.8 kg in mass. Only 3 lunars are >4 kg in mass.
>>
>> Another issue (probably more important) is that lunar escape velocity
>> is only 2.4 km/s and very little material ejected from the Moon is
>> going much faster than that. This velocity compares with 20-40 km/s
>> for asteroidal meteorites. Is a rock entering the atmosphere at 2.4
>> km/s going to noticeably incandesce? I don't know. I believe that
>> the space shuttle hits the atmosphere at ~7.7 km/s.
>>
>> Melanie asks:
>>
>> "I asked this a while ago on Greg Catterton's forum, and I was told
>> that rocks
>> from the moon aren't as solid (tough) as Mars rocks, and therefore are
>> less
>> likely to survive entry... yet what about all these Howardites?"
>>
>> Although breccias, most of the lunar meteorites are very tough rocks.
>> Any rock that survives being blasted off the Moon isn't going to
>> disintegrate in Earth's atmosphere any more than an asteroidal or
>> martian meteorite.
>>
>> Steve says:
>> "The moon is close to the earth and material knocked off the moon has
>> a relatively short time to reach the earth."
>>
>> Compared to what? Some lunar meteorites took a million years or more
>> to reach Earth.
>>
>> "Mars is farther away and not protected by a companion and its closer
>> to the asteroid belt so it receives many more impacts than the moon."
>>
>> Not "many more." Only a factor of two greater for Mars, but the
>> average velocity of the impactors is only 60% as great.
>>
>>
>>
>> Randy Korotev
>> Washington University in St. Louis
>>
>> ______________________________________________
>> Visit the Archives at
>> http://www.meteoritecentral.com/mailing-list-archives.html
>> Meteorite-list mailing list
>> Meteorite-list at meteoritecentral.com
>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 7 Sep 2010 21:03:06 -0700
> From: "Richard Montgomery" <rickmont at earthlink.net>
> Subject: Re: [meteorite-list] YD impact "debate"
> To: "'Meteorite-list List'" <meteorite-list at meteoritecentral.com>,
> "E.P. Grondine" <epgrondine at yahoo.com>
> Message-ID: <1AED4ACD8C6140BB94460387A6B0855B at bosoheadPC>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Impact history is almost entirely unknown to the public in general. I
> suspect that the denial of such effects on speciization theory is
> conveniently being ignored by the scientific community whose funding is
> derived by political motive. Who with knowledge of impact history has taken
> the opportunity to go on record with the Nobel Prize committee, for example.
>
> I, for one, consider the ommission of impact history an abomination (yet
> when their consideration for a Prize winner gives more weight to political
> impacts by a human-created spray-cans vs. meteoritic, astronomic and real
> data, who can doubt the motive.)
>
>
> ----- Original Message -----
> From: "E.P. Grondine" <epgrondine at yahoo.com>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Tuesday, September 07, 2010 7:41 PM
> Subject: [meteorite-list] YD impact "debate"
>
>
>> Hi Paul, all -
>>
>> Go to http://cosmictusk.com
>>
>> This "debate" is pretty much all over, though we can expect denial to
>> continue for the next 30 years or so, based on our experience with the KT
>> impacts. All that that denial did was to retard research for much of that
>> time, and I expect that the same thing may happen with this impact.
>>
>> I also think this denial may have to do with the inability of some people
>> to accept that impacts pose a threat, or to give up their earlier
>> explanations for the observed data, or because they view research into
>> impact as a threat to the funding of research more personally important to
>>
>> them.
>>
>> E.P. Grondine
>> Man and Impact in the Americas
>>
>>
>>
>> ______________________________________________
>> Visit the Archives at
>> http://www.meteoritecentral.com/mailing-list-archives.html
>> Meteorite-list mailing list
>> Meteorite-list at meteoritecentral.com
>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 7 Sep 2010 22:17:53 -0600
> From: "Rich Murray" <rmforall at comcast.net>
> Subject: [meteorite-list] Mammoth-Killer Impact Rejected, Richard A.
> Kerr 2010.08.30 10 comments news.sciencemag.org: Rich Murray
> 2010.09.07
> To: <Meteorite-list at meteoritecentral.com>
> Cc: RichMurray.rmforall at gmail.com
> Message-ID: <66A362813E6540D4B50E8C9D1A10F7AA at ownerPC>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Mammoth-Killer Impact Rejected, Richard A. Kerr 2010.08.30 10 comments
> news.sciencemag.org: Rich Murray 2010.09.07
> http://rmforall.blogspot.com/2010_09_01_archive.htm
> Tuesday, September 7, 2010
> [ at end of each long page, click on Older Posts ]
> http://groups.yahoo.com/group/astrodeep/message/67
> [you may have to Copy and Paste URLs into your browser]
> _______________________________________________
>
>
> http://news.sciencemag.org/sciencenow/2010/08/mammoth-killer-impact-rejected.html#sci-comments
>
> Mammoth-Killer Impact Rejected
> by Richard A. Kerr on 30 August 2010, 4:26 PM
> 10 Comments
> _______________________________________________
>
>
> I ran up my white flag too soon -- 23 experts firmly show YDB era Greenland
> ice layer that has unique huge numbers of impact nanodiamonds in 11-page
> paper in J Glaciology: Rich Murray 2010.09.02
> http://rmforall.blogspot.com/2010_09_01_archive.htm
> Thursday, September 2, 2010
> [ at end of each long page, click on Older Posts ]
> http://groups.yahoo.com/group/astrodeep/message/66
> [you may have to Copy and Paste URLs into your browser]
>
> Cox crisply comments; full text of "No evidence"; Comet theory carbonized,
> Rex Dalton, nature.com; fungus found abstract:
> Rich Murray 2010.08.31
> http://rmforall.blogspot.com/2010_08_01_archive.htm
> Tuesday, August 31, 2010
> [ at end of each long page, click on Older Posts ]
> http://groups.yahoo.com/group/astrodeep/message/65
> [you may have to Copy and Paste URLs into your browser]
>
> 3 times more downward energy from directed force of meteor airburst in 3D
> simulations by Mark B. E. Boslough, Sandia Lab 2007.12.17:
> Rich Murray 2010.08.30
> http://rmforall.blogspot.com/2010_08_01_archive.htm
> Monday, August 30, 2010
> [ at end of each long page, click on Older Posts ]
> http://groups.yahoo.com/group/astrodeep/message/63
> [you may have to Copy and Paste URLs into your browser]
>
> excellent Google Earth and ground views of shallow oval craters worldwide,
> Pierson Barretto:
> Rich Murray 2010.08.22
> http://rmforall.blogspot.com/2010_08_01_archive.htm
> Sunday, August 22, 2010
> [ at end of each long page, click on Older Posts ]
> http://groups.yahoo.com/group/astrodeep/message/60
> [you may have to Copy and Paste URLs into your browser]
>
>
> Rich Murray, MA
> Boston University Graduate School 1967 psychology,
> BS MIT 1964, history and physics,
> 1943 Otowi Road, Santa Fe, New Mexico 87505
> 505-501-2298 rmforall at comcast.net
>
> http://groups.yahoo.com/group/AstroDeep/messages
>
> http://RMForAll.blogspot.com new primary archive
>
> http://groups.yahoo.com/group/aspartameNM/messages
> group with 146 members, 1,609 posts in a public archive
>
> http://groups.yahoo.com/group/rmforall/messages
>
> participant, Santa Fe Complex www.sfcomplex.org
> _______________________________________________
>
>
>
> ------------------------------
>
> Message: 6
> Date: Wed, 8 Sep 2010 04:40:52 +0000
> From: Edwin Thompson <etmeteorites at hotmail.com>
> Subject: [meteorite-list] ad - Vesta for sale
> To: <meteorite-list at meteoritecentral.com>
> Message-ID: <BAY155-w429F34CBB3AFA95B0FF69AD1720 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
>
>
> Hello list members. We have listed a small partial slice of Berthoud,
> Colorado on Ebay. Please click on link below to view the specimen.
>
>
> Thank you, Edwin
>
>
>
>
>
>
>
>
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200517246076&ssPageName=STRK:MESELX:IT
>
>
> ------------------------------
>
> Message: 7
> Date: Tue, 7 Sep 2010 22:18:28 -0700 (PDT)
> From: Melanie Matthews <miss_meteorite at yahoo.ca>
> Subject: Re: [meteorite-list] Witnessed fall lunars?
> To: Randy Korotev <korotev at wustl.edu>,
> meteorite-list at meteoritecentral.com
> Message-ID: <29733.71617.qm at web114014.mail.gq1.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> <"Mars is farther away and not protected by a companion and its closer to
> the
> asteroid belt so it receives many more impacts than the moon."
>
> Not "many more." Only a factor of two greater for Mars, but the average
> velocity of the impactors is only 60% as great.>
>
> To add, the side of the Moon that always faces away from Earth would be just
> as
> vulnerable to bombardment as Mars is..
>
>
> -----------
> -Melanie
> IMCA: 2975
> eBay: metmel2775
> Known on SkyRock Cafe as SpaceCollector09
>
> I eat, sleep and breath meteorites 24/7.
>
>
>
> ----- Original Message ----
> From: Randy Korotev <korotev at wustl.edu>
> To: meteorite-list at meteoritecentral.com
> Sent: Tue, September 7, 2010 2:06:15 PM
> Subject: Re: [meteorite-list] Witnessed fall lunars?
>
>
>> MikeG asks:
>
>> "Is there a theory for why there have been no witnessed falls of lunar
>> meteorites? It seems odd to me that we have 4 Martian witnessed falls
>> (Shergotty, Chassigny, Zagami, Nakhla, and almost Lafayette) and no
>> lunars."
>
> One issue is that these 5 meteorites are 5 kg, 4 kg, 18 kg, 10 kg, and 0.8
> kg in
> mass. Only 3 lunars are >4 kg in mass.
>
> Another issue (probably more important) is that lunar escape velocity is
> only
> 2.4 km/s and very little material ejected from the Moon is going much faster
> than that. This velocity compares with 20-40 km/s for asteroidal
> meteorites.
> Is a rock entering the atmosphere at 2.4 km/s going to noticeably
> incandesce? I
> don't know. I believe that the space shuttle hits the atmosphere at ~7.7
> km/s.
>
> Melanie asks:
>
> "I asked this a while ago on Greg Catterton's forum, and I was told that
> rocks
> from the moon aren't as solid (tough) as Mars rocks, and therefore are less
> likely to survive entry... yet what about all these Howardites?"
>
> Although breccias, most of the lunar meteorites are very tough rocks. Any
> rock
> that survives being blasted off the Moon isn't going to disintegrate in
> Earth's
> atmosphere any more than an asteroidal or martian meteorite.
>
> Steve says:
> "The moon is close to the earth and material knocked off the moon has a
> relatively short time to reach the earth."
>
> Compared to what? Some lunar meteorites took a million years or more to
> reach
> Earth.
>
> "Mars is farther away and not protected by a companion and its closer to the
> asteroid belt so it receives many more impacts than the moon."
>
> Not "many more." Only a factor of two greater for Mars, but the average
> velocity of the impactors is only 60% as great.
>
>
>
> Randy Korotev
> Washington University in St. Louis
>
> ______________________________________________
> Visit the Archives at
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
>
>
>
>
> ------------------------------
>
> Message: 8
> Date: Tue, 7 Sep 2010 22:46:12 -0700
> From: "Rob Matson" <mojave_meteorites at cox.net>
> Subject: [meteorite-list] Shielding of the Moon by earth
> To: <meteorite-list at meteoritecentral.com>
> Message-ID: <GOEDJOCBMMEHLEFDHGMMMEGAEFAA.mojave_meteorites at cox.net>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Melanie/List,
>
> The side of the Moon that faces the Earth is only ~barely~ shielded
> by the earth compared to the side facing away from Earth. In fact,
> I would be surprised if the difference is even detectable as far as
> cratering density. From the Moon's surface, the earth subtends
> about 1.9 degrees, so a Full Earth looks over 14 times larger (in
> "area") than does a Full Moon from earth. While that may seem large,
> the amount of angular space shielded by the earth is tiny -- about
> one part in 7000 for any portion of the lunar hemisphere with a
> view of the earth. In other words, square mile for square mile,
> if the earth had the Moon's vacuum, its surface would get hit just
> as often as the Moon's. --Rob
>
>
>
> ------------------------------
>
> Message: 9
> Date: Wed, 8 Sep 2010 01:01:10 -0700 (PDT)
> From: Melanie Matthews <miss_meteorite at yahoo.ca>
> Subject: Re: [meteorite-list] Shielding of the Moon by earth
> To: Rob Matson <mojave_meteorites at cox.net>,
> meteorite-list at meteoritecentral.com
> Message-ID: <570654.89276.qm at web114010.mail.gq1.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> I see, but the other side of the moon does look a lot more heavily cratered
> than
> that "shielded" by Earth..
>
>
> -----------
> -Melanie
> IMCA: 2975
> eBay: metmel2775
> Known on SkyRock Cafe as SpaceCollector09
>
> I eat, sleep and breath meteorites 24/7.
>
>
>
> ----- Original Message ----
> From: Rob Matson <mojave_meteorites at cox.net>
> To: meteorite-list at meteoritecentral.com
> Sent: Tue, September 7, 2010 10:46:12 PM
> Subject: [meteorite-list] Shielding of the Moon by earth
>
> Hi Melanie/List,
>
> The side of the Moon that faces the Earth is only ~barely~ shielded
> by the earth compared to the side facing away from Earth. In fact,
> I would be surprised if the difference is even detectable as far as
> cratering density. From the Moon's surface, the earth subtends
> about 1.9 degrees, so a Full Earth looks over 14 times larger (in
> "area") than does a Full Moon from earth. While that may seem large,
> the amount of angular space shielded by the earth is tiny -- about
> one part in 7000 for any portion of the lunar hemisphere with a
> view of the earth. In other words, square mile for square mile,
> if the earth had the Moon's vacuum, its surface would get hit just
> as often as the Moon's. --Rob
>
> ______________________________________________
> Visit the Archives at
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
>
>
>
>
> ------------------------------
>
> Message: 10
> Date: Wed, 8 Sep 2010 01:20:09 -0700
> From: "Rob Matson" <mojave_meteorites at cox.net>
> Subject: Re: [meteorite-list] Shielding of the Moon by earth
> To: "Melanie Matthews" <miss_meteorite at yahoo.ca>,
> <meteorite-list at meteoritecentral.com>
> Message-ID: <GOEDJOCBMMEHLEFDHGMMIEGCEFAA.mojave_meteorites at cox.net>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Melanie,
>
>> I see, but the other side of the moon does look a lot more
>> heavily cratered than that "shielded" by Earth...
>
> I suspect this has more to do with the relative ages of the
> surfaces than the cratering rates. Maria are nearly absent
> from the lunar farside, and the nearside Maria have erased
> the evidence of earlier impact cratering. --Rob
>
>
>
> ------------------------------
>
> Message: 11
> Date: Wed, 8 Sep 2010 03:12:48 -0700 (PDT)
> From: Steve Dunklee <steve.dunklee at yahoo.com>
> Subject: Re: [meteorite-list] Shielding of the Moon by earth
> To: miss_meteorite at yahoo.ca, mojave_meteorites at cox.net,
> meteorite-list at meteoritecentral.com
> Message-ID: <129962.6955.qm at web113903.mail.gq1.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Most of the shielding is done by earths gravity well not its area. If mars
> had no atmosphere it would look battered like the moon. And most of the
> material knocked off the moon is either returns to the moon or sucked in by
> earths gravity in a relatively short time. Some day there may be a witnessed
> lunar fall. Cheers Steve
>
>
>
>
>
>
> ------------------------------
>
> Message: 12
> Date: Wed, 8 Sep 2010 13:01:24 +0200
> From: "Martin Altmann" <altmann at meteorite-martin.de>
> Subject: Re: [meteorite-list] Shielding of the Moon by earth
> To: <meteorite-list at meteoritecentral.com>
> Message-ID: <001001cb4f45$2def5b30$89ce1190$_at_de>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Steve,
>
>>is either returns to the moon or sucked in by earths gravity in a
> relatively short time.
>
> Relatively to what?
>
> Just googling around I found transit times of the lunaites from Moon to
> Earth
> between a couple of tens of thousands of years up to 8 million years.
>
> The travelling times of many Martian meteorites fall also well into that
> time frame.
>
> Best!
> Martin
>
>
> -----Urspr?ngliche Nachricht-----
> Von: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von Steve
> Dunklee
> Gesendet: Mittwoch, 8. September 2010 12:13
> An: miss_meteorite at yahoo.ca; mojave_meteorites at cox.net;
> meteorite-list at meteoritecentral.com
> Betreff: Re: [meteorite-list] Shielding of the Moon by earth
>
> Most of the shielding is done by earths gravity well not its area. If mars
> had no atmosphere it would look battered like the moon. And most of the
> material knocked off the moon is either returns to the moon or sucked in by
> earths gravity in a relatively short time. Some day there may be a witnessed
> lunar fall. Cheers Steve
>
>
>
>
> ______________________________________________
> Visit the Archives at
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
>
> ------------------------------
>
> Message: 13
> Date: Wed, 8 Sep 2010 06:16:23 -0700 (PDT)
> From: Michael Johnson <michael at rocksfromspace.org>
> Subject: [meteorite-list] Rocks from Space Picture of the Day -
> September 8, 2010
> To: meteorite-list at meteoritecentral.com
> Message-ID:
> <242581942.584241283951783087.JavaMail.root at mbs1.homesteadmail.com>
> Content-Type: text/plain; charset=utf-8
>
> http://www.rocksfromspace.org/September_8_2010.html
>
>
> ------------------------------
>
> Message: 14
> Date: Wed, 8 Sep 2010 07:49:15 -0700 (PDT)
> From: Steve Dunklee <steve.dunklee at yahoo.com>
> Subject: Re: [meteorite-list] Witnessed fall lunars?still no clear
> answere
> To: almitt2 at localnet.com, meteorite-list at meteoritecentral.com
> Message-ID: <141864.14003.qm at web113907.mail.gq1.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi everyone. You did a good job of thrashing my response without giving an
> answere to the original question. Why are there no lunar witnessed falls? DR
> kortev did say there are twice as many Martian impacts,which to me is a lot
> or many more. Another person questioned if they would have enough velocity
> to be seen which is a verry good point because some would reach terminal
> velocity much sooner than an object from mars or the astroid belt. The
> amount of time recovered lunars take to reach earth has been said to be the
> same as mars meteorites. I am beginning to believe it may be a matter of
> recognition. A lunar would reach terminal velocity 20 or more miles up and
> fall without making a sound. And if it did make a sound the person finding
> it would do everyones "is it a meteorite" test. Brown or green crust? Doesnt
> stick to a magnet.vesicles on the crust. Must not be a meteorite. And what
> size does it take to launch a rock from the moon?small would do it.
> Cheers Steve
>
>
>
>
>
>
> ------------------------------
>
> Message: 15
> Date: Wed, 8 Sep 2010 08:34:42 -0700 (PDT)
> From: Adam Hupe <raremeteorites at yahoo.com>
> Subject: Re: [meteorite-list] Witnessed fall lunars?still no clear
> answere
> To: Adam <meteorite-list at meteoritecentral.com>
> Message-ID: <890019.37485.qm at web30706.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> I think most of it comes from lack of recognition. Lunar meteorites do not
> seem
> to lose as much of their mass when entering the atmosphere so probably do
> not
> produce huge bolides. Chondrites, on the other hand generally burn up 90%
> or
> more, if they survive at all.
>
> For some reason, Martian meteorites tend to be larger in size so probably
> put
> out more light. For the most part, they have very black glossy crusts
> (Eucrite
> like) which makes them very easy to recognize.
>
>
> The Moroccans have proved that once a searcher has been taught what to look
> for,
> success is soon to follow if a reasonable effort is put forth. If I read
> Randy's site correctly, no lunar meteorites were found in Northwest Africa
> last
> year and the peak was around 4 or 5 years ago. Each and every lunar
> meteorite
> found in the hot deserts was a tough pull but it can be done.
>
> Now that we have gained all of this knowledge from the NWA gold rush which
> is
> now over, it is time to work the next plateau which most believe is the
> Mojave.
>
>
> Happy Hunting,
>
> Adam
>
>
>
> ------------------------------
>
> _______________________________________________
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
> End of Meteorite-list Digest, Vol 85, Issue 13
> **********************************************
>
Received on Wed 08 Sep 2010 02:02:34 PM PDT