[meteorite-list] Comet smashes triggered ancient famine ???

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Sun, 11 Jan 2009 11:09:45 -0700 (MST)
Message-ID: <52303.71.226.60.25.1231697385.squirrel_at_timber.lpl.arizona.edu>

Hi Doug:

This is one of many models for the capture and a very possible one.
However, from what I see of the obital evolution and the actual abstract,
I would say that prior to capture, in this model, SL9 was a Jupiter family
comet which is a far cry from an asteroid belt object (had to come close
to Jupiter multiple times).

The asteroid belt goes out to 3.3 AU, so not with nearly 2 AU of Jupiter,
not like the pre-capture SL9.

Larry
PS Never said it was a dramatic capture!

On Sun, January 11, 2009 10:50 am, mexicodoug at aim.com wrote:
> Larry wrote:
>
>
> "1. As far as I know, scientists still do not know where SL9 came from
> ("beyond Neptune"). Probably a captured comet that happened to come too
> close to Jupiter on its first pass or one of its first passes into the
> inner part of the Solar System."
>
> Hi Larry, Listees,
>
>
> IMO, it was far from that dramatic sort of initial Jovian fishing
> expedition in those passes, in that SL9, before it's chaotic Jupiter
> capture looked like one of our favorite kinds of asteroids with an orbit
> likely CONFINED inside the main asteroid belt and with sufficiently of low
> inclination (though with lower probability it could have been stuck a
> little further out, at most, into the zone between Jupiter and Saturn).
> While all short period comets like SLP have a
> pinball aspect to their orbits before getting stuck within, say, inside
> Neptune's orbit, SL9 just did what any meteoroid with potential would
> have done in that it got too close to Jupiter and stretched out its orbit
> like pulling a rubber band. As this is thought to have happened right at
> aphelion, the comet was basically at a standstill when Jupiter bumbled by
> and it transferred into a Jovian orbit by basically falling into Jupiter
> in an extremely eccentric orbit (as you point out), and from there on,
> just got too close to Jupiter as Jupiter and the Sun ironed out tyheir
> differences without JPL pushing the comet's outgassing buttons.
>
> Here is a sc
> ienific eplanation and a graphical evolution of the capture orbits as
> calculated by astrophysicists: http://tinyurl.com/742lbr
>
>
> Of course, where SL9, or anything else for that matter before being in
> the e.g., asteroid belt, came from, whether 25 or 2.5 billion years
> earlier, makes for good philosophy.
>
> A minor sampling of thoughts on this event from a meteoritical
> perspective...and for all good hearted Comet-fearing humans:
>
> The collision of SL9 with Jupiter was a great event to have been alive
> to have observed, but should be put in the appropriate context regarding
> orbit dynamics and the inner Solar system (read: frequencies of collision
> with Earth). While such a Jupiter collision may well be a once in 6000
> (as you suggested) year event, one very pleasing rigorous
> analysis concluded that such event:
>
> " In particular, we show that, for Jupiter-interacting* comets of
> greater than 1 km diameter, a Jupiter impact takes place every 500 to 1000
> years, and an Earth impact every 2 to 4 million years."
>
> The sort of study great pops the ballon of theories suggesting that
> comets frequently strike Earth (and shape evolution frequently in thousands
> or tens of thousands of years periods). The important detail lies within
> the observation that the residence time for comets in the Terrestrial
> (inner) Solar system is so short and chaotic from an
> orbital perspective, and the planets so small (for example, see Larry's
> cross section , but he was actually waaaaay overestimating it since we
> need to also consider the inclinations of the comets), that there is
> virtually nil chance = 2 - 4 million years vs. what we saw happen on
> Jupiter. Furthermore, what led to that collision, as has already been
> suggested is that Jupiter was able to capture the comet to start with. That
> is not something the Earth is adept at doing considering the relative size
> of the Sun and its gravitational potential vs. ours in the uptown part of
> the Solar neighborhood. Here is the excellent statistical vs.
> observational treatise by T. NAKAMURA (National Astronomical Observatory,
> Japan) and H. KURAHASHI (Sano-Fuji Optics
> Company, Japan), THE ASTRONOMICAL JOURNAL, 115:848-854, Feb. 1998.
>
>
> http://www.iop.org/EJ/article/1538-3881/115/2/848/970144.html
>
>
> *ok, so have the wild card of hyperbolic comets and highly inclined
> rogue comets and the likes of the kitchen sink of things that don't fit
> nicely into the Solar system intro textbook. Perhaps this provides some
> SOLice for the frequent Terrestrial-cometary collision proponents.
>
>
> Anyway, this is my take on it Larry, and it is based on oldies but
> goodies regarding the papers cited. I can't find, and don't know that
> anyone has done anything particularly revolutionary since then.
>
> Best wishes, great health and keep looking up,
> Doug
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: lebofsky at lpl.arizona.edu
> To: ensoramanda at ntlworld.com
> Cc:20meteorite-list at meteoritecentral.com
> Sent: Sun, 11 Jan 2009 6:54 am
> Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ???
>
>
>
>
> Hi Graham and Rob:
>
>
> Some of this is from memory and some of this I had to look up. David
> Levy
> was actually working part time for me at the time doing education outreach,
> so I know some of the details.
>
> 1. As far as I know, scientists still do not know where SL9 came from
> ("beyond Neptune"). Probably a captured comet that happened to come too
> close to Jupiter on its first pass or one of its first passes into the
> inner part of the Solar System.
>
> 2. At some point in time (1960s to 1970s), the comet(?) soon to be
> called SL9 was captured in a 2-year orbit around Jupiter. Good for it, a
> new moon of Jupiter!
>
> 3. However in July of 1992, SL9 passed within 30,000 to 40,000 km of
> Jupiter's cloud tops (Jupiter radius is about 71,500 km). This is within
> the Roche limit of Jupiter (gravity-induced tides from Jupiter stronger
> than the strength of the material that makes up the body; a little more
> complicated than that, but good enough for this).
>
> 4. Observed first seen by Carolyn Shoemaker (observers Gene and Carolyn
> Shoemaker and David Levy; interesting story). Then confirmed by Jim
> Scotty
> here in Arizona (the first famous image of the string of pearls).
>
> 5. Soon determined to be in orbit around Jupiter (though only "seen"
> once prior to that but not noticed by the person who took the image). A
> highly elliptical orbit that had it going as far as 50,000,000 km from
> Jupiter
> (but still in orbit). Repeating myself, a 2-year orbit, probably in
> orbit for 20 or 30 years.
>
> 6. Soon to be determined that its orbit was continually changing
> slightly (gravity of the Sun and mass loss of the comet which alters the
> orbit slightly). The result was that in Juuly of 2004, it would be at its
> closest to Jupiter again, but this time, its closest distance to Jupiter
> would be 45,000 from the center of Jupiter, 26,500 BELOW the cloud tops of
> Jupiter!
>
>
> 7. So, the reason that all of the pieces hit Jupiter was that they were
> all in the same orbit, just strung out in space (and time along an orbit
> that got the pieces way too close to Jupiter).
>
> 8. I think that the best estimates (not all agree) are that the largest
> pieces were at most 1-2 km in diameter with most pieces less that 1 km in
> diameter. This makes this event a once in a thousand-year event (give or
> take).
>
> 9. This helps explain crater chains on two of Jupiter's satellites:
> Europa
> and Ganymede (16 total?). A comet gets too close to Jupiter, breaks up and
> you get a string of comets that, on their way away from Jupiter run into
> one of the satellites, leaving a crater chain. Too close together and
> there would not be a chain. Too far apart and only one or two would hit
> the satellite and the othe rs would miss.
>
> To get crater chains on Earth, you would have to have a comet or
> asteroid break up before hitting the Earth, either by a close approach to
> Earth
> (unlikely) of the Sun. However, it is unlikely that this object would
> get captured by the Earth (they are moving fast and Earth not that
> massive).
>
> A breakup as the object was approaching the Earth (say in the
> atmosphere) would not give the pieces time enough to spread out and make
> multiple craters (the long discussion on double craters on Earth). So the
> pieces, as I said before, would have to be close enough together in order
> for the individual pieces to hit the moving Earth target and really close
> to make a chain on Earth. The Earth is moving at 30 km/s and a comet is
> moving at probably 40 or 45 km/s. So, you can easily figure out how close
> the pieces have to be.
>
> A bunch of impacts over a few thousand years is another story that is
> beyond the above discussion.
>
> Larry
>
>
>
>
>
>
>
> On Sun, January 11, 2009 2:49 am, ensoramanda at ntlworld.com wrote:
>
>> Hi Rob,
>>
>>
>>
>> Went to a lecture at our astronomy society about Jupiter and it
>>
> acting to
>> capture or perturb objects (friend or foe etc) the other night....
> and I
>> believe it was said that SL9 only made two passes before it met
> jupiter
>> again on jupiters next turn around the sun and was thus flung out
> never
>> to be seen again. eg
> Jupiter was on the opposite side of the sun on
> SL9's
>
>> first time round with no effect and thus was very close 2nd time round
>> and able to change its orbit again.
>>
>> I hope I remembered that right!
>>
>>
>>
>> Graham Ensor, UK
>>
>>
>>
>>
>> ---- Rob McCafferty <rob_mccafferty at yahoo.com> wrote:
>>
>>
>>> Fair point, but it may well be a poor choice of words on my point.
>>>
>>>
>>
>> The "Swarms"/"showers" you mention are what are suggested in the book.
>> Several objects arriving in quick sucession are not unusual, however.
>> There is evidene of it happening on most solid bodies. They all have
>> strings of impact craters where many objects obviously arrived in a
>> matter of hours producing chains of craters. My problem with this is
> that
>> the authour is perhaps suggesting several over the last few millenia.
> If
>
>> the "chain" events were that prevalant, one would expect them to
> dominate
>> on solid bodies and they don't.
>>
>> Your points are well made. I was not aware that SL9 was in orbit of
>> Jupiter. The implications of this are complex and I'll need to check
>>
> how
>> long for. I Doubt it was for long but even so, how this is related to
>> comets and the earth is beyond me at this time.
>>
>> Rob
>>
>>
>>
>>
>> --- On Sat, 1/10/09, lebofsky at lpl.arizona.edu
>>
> <lebofsky at lpl.arizona.edu>
>
>> wrote:
>>
>>
>>
>>> From: lebofsky at lpl.arizona.edu <lebofsky at lpl.arizona.edu>
>>> Subject: Re: [meteorite-list] Comet
>>>
> smashes triggered ancient famine ???
>
>>> To: rob_mccafferty at yahoo.com
>>> Cc: "tracy latimer" <daistiho at hotmail.com>,
>>> meteorite-list at meteoritecentral.com Date: Saturday, January 10, 2009,
>>> 11:47 PM
>>> While I have not read this book, generally, comets cannot
>>> hit the Earth over a short interval like SL9. SL9 was in orbit around
>>> Jupiter. It is
>>> highly unlikely that a comet could be captured in orbit around Earth.
>>> Continuous bombardment on Earth only happens in movies
>>> unless there is a massive swarm of objects (like in a meteor shower).
>>>
>>> The Earth is a moving target, so if one comet piece were to
>>> hit the Earth, it is unlikely that a second or third one in a similar
>>> orbit would hit, unless the cluster was VERY bunched together. The
> Earth
>
>>> would be long gone!
>>>
>>> The Earth's orbital velocity is about 30 km/s and its
>>> diameter is about 12,750 km. So the Earth moves its diameter in
> about 425
>>> seconds. If the comet pieces were farther apart than that, only one
>>> piece would hit.
>>>
>>> Larry
>>>
>>>
>>>
>>> On Sat, January 10, 2009 4:06 pm, Rob McCafferty wrote:
>>>
>>>
>>>> This is not a new idea. Mike Baille's book
>>>>
>>>>
>>> "Exodus to Arthur" makes
>>>
>>>
>>>> interesting reading on the idea that comets may have
>>> triggered many human
>>>> catastrophies in the past. His book is based on
>>> dendochronology with
>>>> support from other sources. At the time of publishing
>>> 20c.2000, there was a
>>>
>>>> gap in the Greenland Ice core during the 6th Century.
>>>>
>>>> The first third of the book is compelling reading but
>>>>
>>>>
>>> for me does little
>>>> to convince me that it was anything other than
>>> volcanic eruptions. The
>>>> latter part of the book is based on written accounts,
>>> myths and legends
>>>> to make a the suggestion that clusters of small comets
>>> may have been
>>>> involved, small fragments arriving in short interval
>>> like SL9 did on
>>>> Jupiter in 1994.
>>>> He's as objective as he can be but is clearly
>>>>
>>>>
>>> convinced of the cometary
>>>> contribution in at least a few cases.
>>>>
>>>> Rob McC
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --- On Fri, 1/9/09, tracy latimer
>>>>
>>>>
>>> <daistiho at hotmail.com> wrote:
>>>
>>>
>>>>
>>>>
>>>>> From: tracy latimer <daistiho at hotmail.com>
>>>>> Subject: Re: [meteorite-list] Comet smashes
>>>>>
>>>>>
>>> triggered ancient famine ???
>>>>> To: "Paul" <bristolia at yahoo.com>,
>>>>>
>>>>>
>>> meteorite-list at meteoritecentral.com
>>>>> Date: Friday, January 9, 2009, 7:15 PM
>>>>>
>>>>>
>>>>>
>>>>>> From what little research I did, I had
>>>>>>
>>>>>>
>>> understood that a
>>>>>>
>>>>> substantial chunk of the sun-blotting fog was
>>> actually 'vog', which
>>>>> outgassed from major eruptions in Iceland.
>>> Iceland underwent several
>>>
>>>
>>>>> periods of volcanic activity during the 'Dark
>>> Ages', where multiple
>>>
>>>
>>>>> volcanic vents burped out stifling clouds of gas.
>>> The gas periodically
>>>
> 0A>>
>
>>>>> got so thick and noxious that it poisoned
>>> vegetation, killed animals,
>>>>> and sickened almost everyone else; there was at
>>> least one major exodus
>>>>> of survivors around 770 a.c.e.
>>>>>
>>>>> Tracy Latimer
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>
>>>>>
>>>>>
>>>>>> Date: Fri, 9 Jan 2009 07:12:59 -0800
>>>>>> From: bristolia at yahoo.com
>>>>>> To: meteorite-list at meteoritecentral.com
>>>>>> Subject: [meteorite-list] Comet smashes
>>>>>>
>>>>>>
>>> triggered
>>>>>>
>>>>> ancient famine ???
>>>>>>
>>>>>> Comet smashes triggered ancient famine
>>>>>> January 7, 2009 by Ker Than
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>
> http://www.newscientist.com/article/mg20126882.900-comet-smashes-trigge
>
>>>
>>>>>
>>> red-ancient-famine.html?DCMP=OTC-rss&nsref=online-news
>>>>>>
>>>>>> Abbott, D. H., P. Biscaye, J. Cole-Dai, and D.
>>>>>>
>>>>>>
>>> Breger,
>>>
>>>
>>>>>>
>>>>> 2008,
>>>>>
>>>>>
>>>>>
>>>>>> Magnetite and Silicate Spherules from the
>>>>>>
>>>>>>
>>> GISP2 Core
>>>
>>>
>>>>>>
>>>>> at the 536 A.D. Horizon
>>>>>> American Geophysical Union, Fall Meeting 2008,
>>>>>>
>>>>>>
>>>>>>
>>>>> abstract #PP41B-1454
>>>>>>
>>>>>>
>>>>>
>>>
> http://www.agu.org/cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&rang
>
>>>
>>>>>
>>>
> e=1&directget=1&application=fm08&database=%2Fdata%2Fepubs%2Fwais%2Finde
>>>
>>>>>
>>> xes%2Ffm08%2Ffm08&maxhits=200&=%22PP41B-1454%22
>>>>>>
>>>>>> and
>>>>>>
>>>>>>
>>> http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A
>>>
>>>
>>>>>>
>>>>>>
>>>>>> Yours,
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Paul
>>>>>>
> H.
>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ______________________________________________
>>>>>> http://www.meteoritecentral.com
>>>>>> Meteorite-list mailing list
>>>>>> Meteorite-list at meteoritecentral.com
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>>>
>>>
>>>>>
>>> _________________________________________________________________
>>>
>>>
>>>>> Windows Live???????????????: Keep your life in sync.
>>>>>
>>>>>
>>>>>
>>>
> http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t1_allup_explore_01200
>
>>> 9
>>>
>>>
>>>>> ______________________________________________
>>>>> http://www.meteoritecentral.com
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>>>>>
>>>>>
>>>>>
>>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>>>
>>>
>>>>>
>>>>
>>>>
>>>>
>>>> ______________________________________________
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>>>>
>>>>
>>>>
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>>>
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>>>>
>>>>
>>
>>
>>
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Received on Sun 11 Jan 2009 01:09:45 PM PST