Re: [meteorite-list] Comet smashes triggered ancient famine ???
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_mccaffe...@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, lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu wrote: From: lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: rob_mccaffe...@yahoo.com Cc: tracy latimer daist...@hotmail.com, meteorite-list@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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=online-news Abbott, D. H., P. Biscaye, J. Cole-Dai, and D. Breger, 2008, Magnetite and Silicate Spherules from the GISP2 Core
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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, lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu wrote: From: lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: rob_mccaffe...@yahoo.com Cc: tracy latimer daist...@hotmail.com, meteorite-list@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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=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=tablemultiple=1rang e=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Finde xes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list _ Windows Liveââ¢: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t1_allup_explore_01200 9 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http
Re: [meteorite-list] Comet smashes triggered ancient famine ???
Larry All, Thanks much for taking the time to run through these details. Could you expand on your point #7 below? I get that the string of pearls were in the same orbit as each other and that the orbit was due to intersect with Jupiter. But I'd never really thought before about these impacts unfolding from, I think, July 16 - 22, 1994, and assume that by this point, for all intents and purposes, SL9 was on the same piece of railroad track as Jupiter itself...? Many thanks, Dave www.fallingrocks.com -Original Message- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of lebof...@lpl.arizona.edu Sent: Sunday, January 11, 2009 7:55 AM To: ensorama...@ntlworld.com Cc: meteorite-list@meteoritecentral.com 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 others 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, ensorama...@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
Re: [meteorite-list] Comet smashes triggered ancient famine ???
Dave: Here is a link to diagram of the comet in orbit around Jupiter. This is to scale, so the orbit is very long and narrow and it major axis is about 350 times the diameter of Jupiter (50,000,000 km vs. 150,000 km). http://www.astrosociety.org/education/publications/tnl/27/jupiter2.html If you expand it (so not to scale) here is what it looked like: http://www.astrosociety.org/education/publications/tnl/27/27.html Again, the orbit major axis was 50.000,000 km and the trail (which lengthed over time) was probably about 5,000,000 km which is why it took 5 days to do its thing. Each piece had a slightly different orbit due to what happened when it broke up plus any effects due to the pull of the Sun and non-gravitational things (each one had a tail which will gently push the comet pieces). Jupiter is in orbit around the Sun and the comet was just like any of Jupiter's satellites, was in orbit around Jupiter. SL9 was a captured satellite of Jupiter. It just so happened that in this case, the orbit at it closest, got too close to Jupiter! I hope this helps. Larry On Sun, January 11, 2009 8:25 am, Dave Gheesling wrote: Larry All, Thanks much for taking the time to run through these details. Could you expand on your point #7 below? I get that the string of pearls were in the same orbit as each other and that the orbit was due to intersect with Jupiter. But I'd never really thought before about these impacts unfolding from, I think, July 16 - 22, 1994, and assume that by this point, for all intents and purposes, SL9 was on the same piece of railroad track as Jupiter itself...? Many thanks, Dave www.fallingrocks.com __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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 way 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: lebof...@lpl.arizona.edu To: ensorama...@ntlworld.com Cc:20meteorite-l...@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
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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, lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu wrote: From: lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: rob_mccaffe...@yahoo.com Cc: tracy latimer daist...@hotmail.com, meteorite-list@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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=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=tablemultiple=1rang e=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Finde xes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list _ Windows Liveâââ¬Å¾Ã¢: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t1_allup_explore_01200 9 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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, lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu wrote: From: lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: rob_mccaffe...@yahoo.com Cc: tracy latimer daist...@hotmail.com, meteorite-list@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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=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=tablemultiple=1rang e=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Finde xes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list _ Windows Liveââ¢: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t1_allup_explore_01200 9
Re: [meteorite-list] Comet smashes triggered ancient famine ???
Hi Larry, In the likely model for precapture SL9 I cited, the perihelion of the comet varies regularly to about 2.5 and 3 AU (in the link: http://tinyurl.com/742lbr I provided, figure 2), which is well within the asteroid belt and its main mass d-planet Ceres' aphelion of 3AU. I was clear about calling it a short period comet with low inclination which is just semantics for a Jupiter family comet as you would like to correct me (but I would not agree, nor disagree or that matter due to relevance). There are a lot of semantics, for example, take the awesome asteroid (944) Hidalgo, named for the Mexican Independence hero and preist. Like it or not, it is generally considered with the main asteroid belt, although it's orbit grazes Saturn before returning to the main asteroid belt, and could be seen as an asteroid model of a SL9 type scenario with a different outcome so far. Certainly neither Hidalgo nor SL9 has a shared recent history with other favorite passive asteroids like Ceres or Vesta, but we can agree that all asteroids do not share genetics, and then there is chaotic dynamics to deal with. My comments regarding the perturbations of the orbit (which was proposed as much more main belt appearing than main belt asteroid Hidalgo), were the gravitational interactions interactions with Jupiter and this is what I perceive to be of meteoritical relevance. The capture in the likely scenario20looks a really whole lot like Jupiter's pull which creates the Kirkwood gaps! In my favorite example of the main belt asteroid 944 also known as the Ingenious Don Hidalgo y Costilla, the steep inclination of Hidalgo is thought to be from a close call after charging the Jovian gravitational windmill. Luckily, Hidalgo Lives. Viva Hidalgo! When Hidalgo is closest to the Sun in the inner main asteroid belt, a very weak coma is suggested. As I mentioned, the how of an object getting to where it is before it eases into its new zone is a great question for just about everything. It was me who used the word dramatic to characterize your description, Probably a captured comet that happened to come too close to Jupiter on its first pass ... into the inner part of the Solar System. That, I would consider an extremely dramatic and highly cool as unlikely scenario. My reply served to downplay this to consider like in the fast lane of the asteroid belt and the effects of mny years of Jupiter-Kirkwood type interactions which iseems the simpler explanation in this case. that is, to Think Hidalgo ... and allow contencious nomenclature a back seat to the spotlight on location and mechanics, even with cross-overs. From your followup, I don't think you would disagree with this, so maybe after much ado, we're both fine with it. Finally, I hope you noted that I support your ideas of plan etary roulette and then, raise them more, of the overblown comet collision proponents, which was IMO the most interesting meteoritite-related comment of my post which escaped your and other's comment, much to the disappointment of little me. That Japanese paper makes me jealous just looking at how beautiful an analysis of collision probabilities can be and how much there is to be learned to develop such elegance in solutions by amateurs (speaking for myself, really). Earth, every 2 to 4 million years ... I wonder what the dinosaurs were thinking ... why us! why! why! best wishes, and great health, Doug -Original Message- From: lebof...@lpl.arizona.edu To: mexicod...@aim.com Cc: meteorite-list@meteoritecentral.com Sent: Sun, 11 Jan 2009 12:09 pm Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? 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, mexicod...@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
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-triggered-ancient-famine.html?DCMP=OTC-rssnsref=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=tablemultiple=1range=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@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_012009 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=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=tablemultiple=1rang e=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Finde xes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list _ Windows Liveâ¢: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t1_allup_explore_012009 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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, lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu wrote: From: lebof...@lpl.arizona.edu lebof...@lpl.arizona.edu Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: rob_mccaffe...@yahoo.com Cc: tracy latimer daist...@hotmail.com, meteorite-list@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 c.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 daist...@hotmail.com wrote: From: tracy latimer daist...@hotmail.com Subject: Re: [meteorite-list] Comet smashes triggered ancient famine ??? To: Paul bristo...@yahoo.com, meteorite-list@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 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: bristo...@yahoo.com To: meteorite-list@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-rssnsref=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=tablemultiple=1rang e=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Finde xes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo
[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-triggered-ancient-famine.html?DCMP=OTC-rssnsref=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=tablemultiple=1range=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Comet smashes triggered ancient famine ???
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 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: bristo...@yahoo.com To: meteorite-list@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-triggered-ancient-famine.html?DCMP=OTC-rssnsref=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=tablemultiple=1range=1directget=1application=fm08database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm08%2Ffm08maxhits=200=%22PP41B-1454%22 and http://adsabs.harvard.edu/abs/2008AGUFMPP41B1454A Yours, Paul H. __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@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_012009 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
