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Problem I - Cratering. 2. The Earth


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#41 indydave

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Posted 06 March 2015 - 08:30 PM

>>
What about objects from ahead of Earth when the Moon is trailing the Earth; the ones coming from the direction of the Sun when the moon is on the far side of the Earth; and the ones coming from the far side when the Moon is between the Earth and the Sun? The fact is that many more objects probably pass between the Earth and Moon than hit either of them.>>

 

If the origin of the bolides is what Brown says, then they would be moving outward slowly.  Those already at 1 AU and further would soon be out of range of Earth, never having much chance to hit Earth.  But they could still hit Moon...until they were pushed out (slowly) further than 250,000 mi.  Those orbiting the Sun at less than 1 AU (due to perhaps being launched retrograde, thus having less orbital speed around the Sun...but still enough speed to escape Earth) would get pushed outward...toward Earth.  These would first have a chance to contact with Moon while they were still 250,000 miles from Earth...perhaps with dozens of chances to be caught by Moon before even getting to 1 AU.  Then those would get other (dozens?) chances to hit Moon after they are further out than 1 AU also.  Those that happen to be the exact speed of Earth's orbit (hard to imagine many of these since they get LAUNCHED so that means their launch speed is ADDED to Earth's...unless they are launched retrograde) would eventually be caught by Moon or Earth.  But these would be a small number compared to the number of those less than 1 AU and those from a bit more than 1 AU to 250,000 miles further out.  Though the Moon has a smaller cross-sectional area, it gets many many more chances to be hit due to the 500,000 mile diameter of its orbit.  If it took (say) 100 years for stuff to be pushed beyond 1 AU+250,000 miles...then the Moon would get many many chances to get hit, which Earth gets a lot fewer.



#42 piasan

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Posted 06 March 2015 - 10:54 PM

>>Pi wrote:
What about objects from ahead of Earth when the Moon is trailing the Earth; the ones coming from the direction of the Sun when the moon is on the far side of the Earth; and the ones coming from the far side when the Moon is between the Earth and the Sun? The fact is that many more objects probably pass between the Earth and Moon than hit either of them.>>
 

Dave answers:
If the origin of the bolides is what Brown says, then they would be moving outward slowly.  Those already at 1 AU and further would soon be out of range of Earth, never having much chance to hit Earth.  But they could still hit Moon...until they were pushed out (slowly) further than 250,000 mi.  Those orbiting the Sun at less than 1 AU (due to perhaps being launched retrograde, thus having less orbital speed around the Sun...but still enough speed to escape Earth) would get pushed outward...toward Earth.  These would first have a chance to contact with Moon while they were still 250,000 miles from Earth...perhaps with dozens of chances to be caught by Moon before even getting to 1 AU.  Then those would get other (dozens?) chances to hit Moon after they are further out than 1 AU also.  Those that happen to be the exact speed of Earth's orbit (hard to imagine many of these since they get LAUNCHED so that means their launch speed is ADDED to Earth's...unless they are launched retrograde) would eventually be caught by Moon or Earth.  But these would be a small number compared to the number of those less than 1 AU and those from a bit more than 1 AU to 250,000 miles further out.  Though the Moon has a smaller cross-sectional area, it gets many many more chances to be hit due to the 500,000 mile diameter of its orbit.  If it took (say) 100 years for stuff to be pushed beyond 1 AU+250,000 miles...then the Moon would get many many chances to get hit, which Earth gets a lot fewer.

Note:  I think this discussion is also productive with reference to "Fire and Brimstone" as it may provide a reasonable estimate of just what may fall back or later impact Earth.

 

First, we need to figure out how those really big craters on the moon came to be.  We're talking about bolides on the order of 10 km in diameter... and up.  Brown says the largest pieces were only 200 meters.  A 200 meter bolide isn't going to make a 160 km impact crater unless it's travelling about a gazillion miles per hour.... and I think you'll agree we can forget water molecules.  Either a lot more much bigger stuff was launched than Brown claims or some other process is at work.

 

Second, let's deal with the amount of stuff that will hit the Moon as it's being launched.  The moon has an angular measurement of about 0.5o.  That means if Earth is spewing out material precisely along the Moon's orbital path, the moon would blocking about 1/720 of it ,,, 0,13%.... with some adjustment for the Moon's gravity.  Unfortunately, the Moon's orbit is mostly equatorial (generally east-west) but the lunch chasm runs largely north-south.  This means the vast bulk of the material will be launched on a trajectory that doesn't even take it anywhere near the moon.  My best guess is that the probability of any particular launched particle hitting the moon would be on the order 1 in 7202 or a few per million.  Yet the moon has 60 craters larger than 100 miles across.

 

Third, the size of the moon's orbit is irrelevant.  It is only "sweeping" an area of space equal to it's surface area with an adjustment for gravity.... as is Earth.

 

Fourth, using Brown's launch velocities, this stuff is going past the moon's orbit very quickly and at a fairly high velocity.  If it comes back to the vicinity of the Earth and Moon, it is some 20x more likely to hit Earth than the Moon.



#43 piasan

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Posted 06 March 2015 - 11:53 PM

Bringing the cratering discussion here as it is much more relevant to the Earth than the moon.
 

>>The moon has 60 impact craters of 100 miles or more. We can reasonably expect Earth to have taken around 1200 of these impacts.>>

That is dead wrong. It will depend a great deal on what the origin of bolides actually is. If Brown is right, and they originate from Earth, stay in that area for a while until they are pushed outward to the Asteroid belt,

I did say "reasonably expect."  We can certainly discuss Brown's claims and how they relate to those big craters on the moon, then we can discuss why Earth wouldn't experience similar impacts and how many we should expect.
 

then the point I made in #74 completely answers this...showing that the effective "sweep" of the Moon is about 60 times wider while the size of the Moon (cross-sectional area) is about 1/3...so the Moon will sweep up 20 times more objects than the Earth would. Plus the Moon would be catching stuff that is nearer the Sun than Earth, while it moves outward. So the Moon (having an orbit that takes it 250,000 miles closer to the Sun than the Earth) will be picking off the objects before they can get into range of Earth.

Post #74 from the other thread is dead wrong.  The moon does nothing to protect Earth from an impact if the Earth is between the moon and the bolide.  These things enter and leave the Earth-moon system in hours and the moon only covers the space once every 4 weeks.  The moon does nothing at all to intercept objects approaching at high angles of inclination with the moon's orbit around the Earth.  In other words, the vast majority will impact Earth unimpeded by the moon.  If I haven't been able to successfully communicate that to you, I respectfully suggest you check with Brown on this one.
 

>>Pi wrote:

Keep in mind, among the craters we're talking about, the ones 100 miles across are the MINIMUM size. Some of these things are in excess of 500 miles across.>>

 

David:
I thought you said (here or one the Earth thread) that one of these would ONLY heat the atm. by a tiny amount...far less than 1 degree. And if its heat went into the ocean it would be many many times LESS. Did I imagine that?

Nope.  As I recall, I said the atmospheric impact was something like 30 millionths  of a degree and you complained about the disposition of the heat  You haven't seen me say anything at all about excessive heat (globally) in the crater discussions, have you?  This one isn't about only about heat.  One impact that creates a hundred mile crater is an extinction event.  The evidence is that Earth should have had hundreds .... even under Brown's model.



#44 indydave

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Posted 07 March 2015 - 08:04 AM

>>First, we need to figure out how those really big craters on the moon came to be.  We're talking about bolides on the order of 10 km in diameter... and up.  Brown says the largest pieces were only 200 meters.  A 200 meter bolide isn't going to make a 160 km impact crater unless it's travelling about a gazillion miles per hour.... and I think you'll agree we can forget water molecules.  Either a lot more much bigger stuff was launched than Brown claims or some other process is at work.>>

And I explained the process...the groups of chunks <200m travelling together would consolidate...THEN impact Moon. Since Moon has no atm they would remain in one piece and make one large crater. 

 

>>Second, let's deal with the amount of stuff that will hit the Moon as it's being launched.  The moon has an angular measurement of about 0.5o.  That means if Earth is spewing out material precisely along the Moon's orbital path, the moon would blocking about 1/720 of it ,,, 0,13%.... with some adjustment for the Moon's gravity. >>

Angular measurement (the amount of space in the sky the Moon occupies) is irrelevant.  The SIZE of the Moon (about 1/3 the area in cross-section as Earth) and the SWEEP of the orbit...DOES matter.

 

>>Unfortunately, the Moon's orbit is mostly equatorial (generally east-west) but the lunch chasm runs largely north-south.  This means the vast bulk of the material will be launched on a trajectory that doesn't even take it anywhere near the moon.>>

If it goes past EV it also cannot hurt Earth since it is not on the plane of Earth's orbit.  In fact if it IS on Earth's plane it STILL cannot hurt E if it goes past EV.  It could ONLY hurt the Moon.  So if you argue that the stuff would miss the Moon, then it also would miss Earth...if it were launched during the Flood as Brown says.  What you don't seem to get is that there are multiple chances each object has to hit the Moon...if it is an asteroid-forming object vs. a comet type object traveling at much faster speeds.  And there's also something to say about how at a distance of 250,000 miles the Moon could block a larger angular area to protect Earth than just 1/3.

 

>>My best guess is that the probability of any particular launched particle hitting the moon would be on the order 1 in 7202 or a few per million.  Yet the moon has 60 craters larger than 100 miles across.>>

Once again you display how ignorant you are of what Brown asserts.  The stuff causing craters on the Moon is not shot directly at Moon.  This calc you make here shows you don't understand that.

 

>>Third, the size of the moon's orbit is irrelevant.  It is only "sweeping" an area of space equal to it's surface area with an adjustment for gravity.... as is Earth.>>

You need to reread my explanation.  I SAID it would catch 1/3 what the Earth catches with each pass (orbit around the Sun) but the swath is 60 times wider than Earth is.  It is in effect sweeping back and forth all the time in a zone that is 500,000 miles wide.  AND it is having many chances to catch stuff moving outward toward Earth before it could hit Earth.  Try to UNDERSTAND my point before you trip all over yourself in your rush to "answer" it.

 

>>Fourth, using Brown's launch velocities, this stuff is going past the moon's orbit very quickly and at a fairly high velocity.  If it comes back to the vicinity of the Earth and Moon, it is some 20x more likely to hit Earth than the Moon.>>

NONE of what plastered the Moon would have been at comet speeds.  Or only a tiny % would be returning comets (and NONE of the asteroids) hitting either the Moon or Earth.  I would agree that anything returning would be 3.66 times more likely to hit Earth (not 20x)...but gravity would have very very little to do with it.  You even agreed that larger stuff would be LEAST affected by gravity...and the same goes for faster stuff. So knock it off about 20x.

 

>>The moon does nothing to protect Earth from an impact if the Earth is between the moon and the bolide.  These things enter and leave the Earth-moon system in hours and the moon only covers the space once every 4 weeks.>>

 

NOT the things Brown describes.  They are pushed outward SLOWLY...from an orbit near to E's to eventually (after centuries) settling into a circular orbit beyond Mars. 

 

>>  The moon does nothing at all to intercept objects approaching at high angles of inclination with the moon's orbit around the Earth.  In other words, the vast majority will impact Earth unimpeded by the moon.  If I haven't been able to successfully communicate that to you, I respectfully suggest you check with Brown on this one.>>

I don't disagree about stuff that would hit the Moon from a N/S direction.  The craters on the poles of the Moon could be from material orbiting E over E's poles, and eventually hitting the Moon from its North or South.  There also undoubtedly are secondary impacts on M's poles too.  If we are talking (as you seem always to be) about conventional thinking about bolides (i.e. that they come from deep space at very high speed and did not originate from E) then yes, those could come from all directions and have about a 3.66x chance to hit the Earth cf to the Moon.  Not 20 or 30 times as you say.

 

>>This one isn't about only about heat.  One impact that creates a hundred mile crater is an extinction event.  The evidence is that Earth should have had hundreds .... even under Brown's model.>>

Ok...then we won't have to include big impacting stuff in our estimate of whether there is lethal HEAT.  Good.  You have so far ignored my asking you to agree with me about large objects falling back and impacting NOT causing overheating.  Are you ready to be done with those and begin to discuss the other 70% which falls back but does NOT impact (at high velocity)?  (We would go to Fire and Brimstone for that). 



#45 piasan

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Posted 07 March 2015 - 03:45 PM

OK.... I have contacted Dave B. for the correct way to calculate the size of Earth compared to that of the moon as a target.  Here is what I proposed to Dave B:
"Briefly, the moon has 60 impact craters 100 mi or more in diameter.  The Earth with 5x the surface area and 6x the gravity is obviously a much bigger gravitational target.  The question is what would the correct adjustment be? I'm guessing it would be either 5(sqrt (6)) = 12.25 or 5(6/sqrt(2)) = 21.2. I know creationist Michael Oard came up with around 19."
 
Here is DaveB's response .... without some of the very technical jargon:
"The ratio of the Earth's capture cross section to that of the Moon depends significantly on the asymptotic (i.e. far from either one) inbound speed vi of the object(s) being captured. If we assume both the Moon and the Earth are spherical and we neglect interaction effects between them due to their close mutual proximity, and pretend each one is capturing its inbound objects independently of the other ..... This means that the capture cross section ratio would match your quoted Oard value of 19 if vi  were about 16.82 km/s. It would never match your guessed value of 12.25 because the minimum value for the capture cross section ratio is 13.435  (emphasis Pi's) (their geometric cross section ratio) which it boils down to when the asymptotic inbound speed is enormous for objects coming into the solar system from interstellar space, and the gravity difference between the Earth and Moon becomes irrelevant. The capture cross section ratio would, however, match your guessed 21.2 value if vi  = 14.17 km/s. ....
My guess as to what a typical average asymptotic inbound speed would be is probably somewhere around 6 km/s since the mean orbital speed of the Earth-Moon barycenter about the Sun is about 29.8 km/s and most of the stuff hitting the Earth & Moon would probably be on comparable orbits going essentially the same way around the Sun with slightly different orbital planes, orbital radii, speeds, and eccentricities. So I would maybe expect a guess for vi of around 20% of the earth's orbital speed might be in the ballpark for the averaged capture cross section ratio then being somewhere around 52. But clearly there is quite a wide degree of latitude & uncertainty in any such estimate.

Note that the σ e /σ m ratio gets much larger for slower inbound objects than for faster ones because then the Earth's greater gravity does a much better job of drawing in objects around it than the Moon's gravity does the slower the objects approach them. For very fast inbound objects neither the Earth's nor the Moon's gravity has much effect in deflecting the object towards themselves and just their geometric cross section is then what captures them."
 

Pi resumes:
So, we were both partly right and both partly wrong. 

 

However, the minimum factor 13.45.  Multiplying that by 60 (the number of craters over 100 mi. in diameter on the moon, we get a minimum of 807 such impacts can reasonably be expected to have happened on Earth.   For that reason, in future discussions, 800 is the number of impacts I will use for what we should expect to see on Earth.



#46 piasan

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Posted 07 March 2015 - 06:13 PM

First, we need to figure out how those really big craters on the moon came to be.  We're talking about bolides on the order of 10 km in diameter... and up.  Brown says the largest pieces were only 200 meters.  A 200 meter bolide isn't going to make a 160 km impact crater unless it's travelling about a gazillion miles per hour.... and I think you'll agree we can forget water molecules.  Either a lot more much bigger stuff was launched than Brown claims or some other process is at work.

And I explained the process...the groups of chunks <200m travelling together would consolidate...THEN impact Moon. Since Moon has no atm they would remain in one piece and make one large crater.

OK.... I just wanted to be absolutely sure we are in agreement that these really big impacts are stuff that has escaped the gravity of the Earth/Moon "system" and has had time to consolidate in space.

 

Second, let's deal with the amount of stuff that will hit the Moon as it's being launched.  The moon has an angular measurement of about 0.5o.  That means if Earth is spewing out material precisely along the Moon's orbital path, the moon would blocking about 1/720 of it ,,, 0,13%.... with some adjustment for the Moon's gravity.  Unfortunately, the Moon's orbit is mostly equatorial (generally east-west) but the lunch chasm runs largely north-south.  This means the vast bulk of the material will be launched on a trajectory that doesn't even take it anywhere near the moon.  My best guess is that the probability of any particular launched particle hitting the moon would be on the order 1 in 7202 or a few per million.  Yet the moon has 60 craters larger than 100 miles across.

Angular measurement (the amount of space in the sky the Moon occupies) is irrelevant.  The SIZE of the Moon (about 1/3 the area in cross-section as Earth) and the SWEEP of the orbit...DOES matter.
 
>>Pi:
Unfortunately, the Moon's orbit is mostly equatorial (generally east-west) but the lunch chasm runs largely north-south.  This means the vast bulk of the material will be launched on a trajectory that doesn't even take it anywhere near the moon.>>
 
Dave:
If it goes past EV it also cannot hurt Earth since it is not on the plane of Earth's orbit.  In fact if it IS on Earth's plane it STILL cannot hurt E if it goes past EV.  It could ONLY hurt the Moon.  So if you argue that the stuff would miss the Moon, then it also would miss Earth...if it were launched during the Flood as Brown says.  What you don't seem to get is that there are multiple chances each object has to hit the Moon...if it is an asteroid-forming object vs. a comet type object traveling at much faster speeds.  And there's also something to say about how at a distance of 250,000 miles the Moon could block a larger angular area to protect Earth than just 1/3.
 
>>Pi:
My best guess is that the probability of any particular launched particle hitting the moon would be on the order 1 in 7202 or a few per million.  Yet the moon has 60 craters larger than 100 miles across.>>
 
Dave
Once again you display how ignorant you are of what Brown asserts.  The stuff causing craters on the Moon is not shot directly at Moon.  This calc you make here shows you don't understand that.

Again, I'm merely confirming that we are in agreement that very little of the launched material will impact the moon during the launch phase itself and these big impacts are due to later encounters with objects that have escaped the gravity of the Earth/Moon and are basically in the wrong place at the wrong time later on.
 

 

Third, the size of the moon's orbit is irrelevant.  It is only "sweeping" an area of space equal to it's surface area with an adjustment for gravity.... as is Earth.

You need to reread my explanation.  I SAID it would catch 1/3 what the Earth catches with each pass (orbit around the Sun) but the swath is 60 times wider than Earth is.  It is in effect sweeping back and forth all the time in a zone that is 500,000 miles wide.  AND it is having many chances to catch stuff moving outward toward Earth before it could hit Earth.  Try to UNDERSTAND my point before you trip all over yourself in your rush to "answer" it.

As I understand your point,  you are claiming that the moon "sweeps" the Earth's orbit basically "cleaning out" a half-million mile wide section of space clearing the path for Earth.  Is that not correct?
 
You do not seem to understand the rebuttal ..... the moon orbits Earth every 28 days.  For 14 of those days it will be behind Earth and do nothing at all to shield it from head-on impacts.  For 14 days, it will be closer to the Sun and do nothing at all to protect Earth from strikes coming in from the side away from the Sun. etc.  Far more of these bolides will pass thru the space between the Earth and the Moon without impacting either one.

These potential impactors travel thru this half-million mile wide space in a few hours.  It takes 28 days for the moon to complete one cycle thru this space,  Most of them will come into the region and impact Earth while the moon isn't even close to them..... the moon only protects the Earth about only 1 in 720 of those impacts due to it's 0.5 degree angular measurement from Earth.... and those are only the ones that approach on the orbital plane of the moon.

Even if the moon were catching "1/3 of what the Earth catches with each pass" that would be only 25%. (Earth gets 3 hits while the moon gets 1... are we going to have a problem with fractions again?) That would still mean 180 impacts on Earth while the moon gets 60.
 
I have been unsuccessful in communicating this to you and I can't think of any way to explain it more clearly.
 

 

Fourth, using Brown's launch velocities, this stuff is going past the moon's orbit very quickly and at a fairly high velocity.  If it comes back to the vicinity of the Earth and Moon, it is some 20x more likely to hit Earth than the Moon.

NONE of what plastered the Moon would have been at comet speeds.  Or only a tiny % would be returning comets (and NONE of the asteroids) hitting either the Moon or Earth.  I would agree that anything returning would be 3.66 times more likely to hit Earth (not 20x)...but gravity would have very very little to do with it.  You even agreed that larger stuff would be LEAST affected by gravity...and the same goes for faster stuff. So knock it off about 20x.

I have already told you that any speed you want is fine... though it should be a minimum of 11.2 km/sec since that's the velocity it left at. Whatever velocity you use, the final crater must be over 100 miles in diameter.   We don't need to worry about the % that returns either.... just the number of impacts.  The 20x was merely my best estimate.  I now have a better estimate of 13.45x MINIMUM and will use that from now on .... with the understanding that it is, in fact, a  MINIMUM.  My earlier estimates (300 to 1200 impacts) are now obsolete in favor of a better estimate based on the minimum likely.... 800.  (Note:  It is interesting ... but admittedly coincidental .... that the average of my earlier numbers is 750.)

You can knock it off about the 3.66x. You are looking at the ratio of radii or diameters. The minimum factor is the cross-sectional area which, for a sphere, is a circle of the same diameter (or radius). The area of a circle is a function of the radius squared. The ratio of Earth's radius to that of the moon is 3.66. Squaring that gives us about 13.45x more area for the Earth as a target.
 
 

>>Pi:
This one isn't about only about heat.  One impact that creates a hundred mile crater is an extinction event.  The evidence is that Earth should have had hundreds .... even under Brown's model.>>

Dave:
Ok...then we won't have to include big impacting stuff in our estimate of whether there is lethal HEAT.  Good.  You have so far ignored my asking you to agree with me about large objects falling back and impacting NOT causing overheating.  Are you ready to be done with those and begin to discuss the other 70% which falls back but does NOT impact (at high velocity)?  (We would go to Fire and Brimstone for that).

 This one isn't about heat... and it's not only about Brown.  The discussion of heat is over at the "Fire and Brimstone" thread.  This one is about ONLY the really big impactors that leave craters in excess of 100 miles across.  Other than there should be some detectable level of heat after 20 years in a crater that big, I have made no comment or claim regarding "overheating" related to these objects.
 
The point here is that just ONE of these objects is enough to cause a global extinction.  Trying to pack 800 of them into a YEC scenario of only 6,000 years isn't going to work as that would be one every 7.5 years on average.  You are trying to put them into a time scale that is only a tiny fraction of that.  Notice, this isn't just a problem for Brown.... it's a biggie for YEC in general.
 



#47 indydave

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Posted 07 March 2015 - 07:34 PM

>>For that reason, in future discussions, 800 is the number of impacts I will use for what we should expect to see on Earth.>>

As I said, the number for Earth vs. Moon depends on what your model is for the origin of comets.  Dave B uses the conventional idea.  I thought we were evaluating Brown's idea.  I might AGREE with Pi if I agreed with him about where comets actually come from.  I thought he wanted to discuss Brown though.



#48 piasan

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Posted 07 March 2015 - 07:51 PM

>>Pi:

If you're on the beach, the tsunami is down to 125-250 m (400-800 feet). and you have about 2.5 hours before it arrives. Not much will survive out to a radius of 1000 miles either.....>>

Dave:
If you are 10,000 miles away in a huge ship made to withstand big waves you would be ok.  BTW, tsunami waves are not a big deal until they get near shore.  You ride up the wave gradually and then back down...big ships far from shore are not hurt by tsunamis. 

The tsunami Dave is talking about are the ones resulting from earthquakes.  At sea, they may be only an inch or two high.  As these waves travel at speeds of over 500 mph, the ships do not "gradually" ride up and back down because the wave will travel the entire length of the ship in only a second or so .... for even the longest of ships.

 

This one is different... think of the splash and waves as a big rock hits water.  So the wave we're talking about would be 400-800 feet high at sea.  This is a problem for even the best built of ships.

 

Even if the ark were pointed directly into the wave, it would not be able to raise the bow quickly enough and within a second or so would be engulfed in water hundreds of feet deep.



#49 indydave

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Posted 07 March 2015 - 08:23 PM

>>You do not seem to understand the rebuttal ..... the moon orbits Earth every 28 days.  For 14 of those days it will be behind Earth and do nothing at all to shield it from head-on impacts.  For 14 days, it will be closer to the Sun and do nothing at all to protect Earth from strikes coming in from the side away from the Sun. etc.  Far more of these bolides will pass thru the space between the Earth and the Moon without impacting either one.  These potential impactors travel thru this half-million mile wide space in a few hours.  It takes 28 days for the moon to complete one cycle thru this space,  Most of them will come into the region and impact Earth while the moon isn't even close to them..... the moon only protects the Earth about only 1 in 720 of those impacts due to it's 0.5 degree angular measurement from Earth.... and those are only the ones that approach on the orbital plane of the moon.>>

This proves YOU don't understand.  In Brown's model it is UNTRUE that the asteroid-stuff would pass through 500,000 miles "in a few hours."  It gets launched beyond EV...with cometary stuff going fast away from Earth on ELLIPTICAL paths.  But other stuff hangs out close to Earth/Moon being in roughly the same orbit as E/M around the Sun.  Then it gets SLOWLY pushed outward for centuries until it finally parks in a circular orbit where it is now...the asteroid belt.  You do NOT understand Brown as well as you've often CLAIMED you do.  As I said, the 1 in 720 number might be true for something coming from deep space where each object gets once chance to hit Moon and one to hit Earth.  But the vast majority of what hit Moon (in Brown's model) was not that type of hit.  When the Moon is nearer the Sun, it doesn't HAVE to protect Earth from asteroid-stuff coming from outside Earth's orbit because that stuff only comes from inside Earth's orbit.  Once it is beyond Earth's orbit, it won't hit Earth anymore...except for the rare event where an asteroid gets sent inward by some perturbation (like what we see today).  The Moon on the other hand got many more hits than Earth while stuff was heading outward...and that hit potential continues until the stuff is 250000 miles further outward from Earth.

 

>>Even if the moon were catching "1/3 of what the Earth catches with each pass" that would be only 25%. (Earth gets 3 hits while the moon gets 1... are we going to have a problem with fractions again?) That would still mean 180 impacts on Earth while the moon gets 60.>>

That would depend on how fast the stuff moves outward...as to whether the Moon gets only one chance to get hit by an object vs. many.  You keep picturing ONLY the conventional idea...of things impacting Earth like comets do or today's asteroids do...on very elliptical orbits.  If the asteroid belt came from Earth as Brown says, it has to begin with a CIRCULAR orbit that moves outward.  If the stuff was on elliptical orbits, then the asteroid belt would look very different than it does.  Also, the impacts on the Moon involve stuff orbiting Earth (while Earth orbits the Sun).  They are like mini-moons and they are on all kinds of orbits beyond EV.  Regardless of how high or low their orbits are or what inclination they have...until they are pushed out past the Moon's orbit, they have a chance to impact the Moon...while they have ZERO chance to hit Earth (except if some collision might cause it to lose its orbital energy).  Picture many shells or spheres of mini-moons surrounding Earth as it travels around the Sun...as does the Moon.  With the Moon revolving around E, this means Moon has many chances to be hit (including at its poles) by the mini-moons while Earth has NO CHANCE AT ALL.  Don't you get this? 

 

>>You can knock it off about the 3.66x. You are looking at the ratio of radii or diameters. The minimum factor is the cross-sectional area which, for a sphere, is a circle of the same diameter (or radius). The area of a circle is a function of the radius squared. The ratio of Earth's radius to that of the moon is 3.66. Squaring that gives us about 13.45x more area for the Earth as a target.>>
 

You are right...13.45 is the right number...I didn't square it as I should have***.  BUT this only would be the likelihood of Earth being hit by a comet-like trajectory (very elliptical).  If Brown's idea is right about asteroid-stuff moving outward on a circular orbit very slowly (being pushed by the Sun's photons), then Moon would get hit many more times than Earth.  Only the stuff in an 8000 mile "deep" layer moving from nearer to the Sun outward past Earth...and is MISSED by the moon's sweep...could hit Earth.  All the other stuff in the 500,000 mile diameter sphere around Earth WOULD be able to hit the Moon. 

 

***How come when you show me a mistake I will admit it right away while you refuse after about a week to admit to the math error I showed you?  Will we ever hear you admit it, or show me why it was NOT a mistake?  Here is this from pg 23 of "Brimstone"

 

Indy:>>Here is what I believe is your new math error.  Each kg of icy stuff which was at -460F (-273C) would take a total of 3.81e6 joules to heat up as a solid, melt, heat up more as a liquid, then boil (if it were all water...which for ease we will assume, as did Pi).  If that number is taken times the total mass Pi says fell back (2.74e21 kg) that gives us 1.04e28 J.  THAT number (not 5.39e26) is the amount to be subtracted from the total energy (4.29e28 J...acc to Pi) of stuff falling back.  That is 24.24%...not 1.25%.  Pretty big difference!>>

 

Pi>> This one isn't about heat... and it's not only about Brown.  The discussion of heat is over at the "Fire and Brimstone" thread.  This one is about ONLY the really big impactors that leave craters in excess of 100 miles across.  >>

You have indeed made a BIG deal about heat from stuff impacting Earth...and even when you used a lot faster speed for these (faster than 5.6km/sec), you still could not show it raising the atm even ONE DEGREE...and it would be many times LESS that it could raise the temp of the ocean.  So you can PRETEND this has nothing to do with heat...but your big deal has been that Brown's idea overheats the Earth to LETHAL temps.  So have you admitted yet (as I showed you for about 2 weeks now) that if 1% fell back and if 30% of what fell back DID impact the ocean at 5.6km/sec then it would NOT overheat the ocean (to 45dC) NOR would it at 10% either?  Stop dilly-dallying.  Let's hear your answer.  I don't CARE if this particular thread started off about whether the moon's surface would melt.  You and I agree it would NOT.  Now what about lethally heating Earth?  What do you say about that???

 

>>Other than there should be some detectable level of heat after 20 years in a crater that big, I have made no comment or claim regarding "overheating" related to these objects.>>>>

Again with the 20 years garbage?  Do ANY YEC's say that every 20 years a big object hits the Moon?  NO THEY DON'T.  Do you just like showing off that you can beat up your own straw men?  Brown says its been 4000 years since the objects hit the Moon.  And I showed you (using the radiative cooling site's calculator) how that heat would all get radiated away (from 3000C to its present temp) in about 1500 years...and you gave me NO REPLY yet to that.  SO the Moon's surface would not be molten (we agree) AND there would be no hot spots inside any of the 60 craters today.  They've ALL been very very cold for 2500 years or so. 

 

>>The point here is that just ONE of these objects is enough to cause a global extinction. >>

We'll consider OTHER supposed causes of extinction AFTER you admit the heat would not be a problem, as you've claimed for 5 years.  Or is it time to get on your horse and gallop off to another topic because you don't like how this one is going for you???



#50 indydave

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Posted 07 March 2015 - 08:26 PM

>This one is different... think of the splash and waves as a big rock hits water.  So the wave we're talking about would be 400-800 feet high at sea.  This is a problem for even the best built of ships.>>

Not if your ship is 10,000 miles away...right?  The splash wouldn't go that far.  I think you said it would be a problem for about 500 miles, IIRC.



#51 indydave

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Posted 08 March 2015 - 10:46 AM

>>I have already told you that any speed you want is fine... though it should be a minimum of 11.2 km/sec since that's the velocity it left at. Whatever velocity you use, the final crater must be over 100 miles in diameter. >>

If we are talking about stuff hitting EARTH, then anything over 11.2km/sec would never hit Earth.  Right?

 

>>I now have a better estimate of 13.45x MINIMUM and will use that from now on .... with the understanding that it is, in fact, a  MINIMUM.  My earlier estimates (300 to 1200 impacts) are now obsolete in favor of a better estimate based on the minimum likely.... 800.  (Note:  It is interesting ... but admittedly coincidental .... that the average of my earlier numbers is 750.)>>

What you are missing is that stuff hitting the Moon is stuff that GOES BEYOND EV.  So NONE of that would hit Earth.  No matter WHAT size the Earth is compared to the Moon.  The Moon also gets NUMEROUS chances per object to get hit...because there is a swarm of stuff travelling with Earth and Moon around the Sun, until it gradually gets pushed outward (as Brown describes).  Not only is 800/1 not right.  Even 1/1 is not.  Please explain how stuff going past EV would EVER hit Earth, unless it was to be on an elliptical path like a comet and then happen to strike either Moon or Earth on one of its journeys back?  I would agree that THOSE objects are 13.45x more likely to hit Earth.  BUT, the impacts we see on the Moon are NOT (acc to Brown's theory) from such return journeys.  Brown says the asteroid stuff (for the most part) goes outward ONCE and then never returns near to Earth.  Go find someone ELSE who would say that most of them DO return and argue with HIM. 

 

This is pretty ridiculous to discuss much more because you have already thrown in the towel by saying if there WERE 13.45x more (based on area of cross-section) that hits Earth, it STILL would not raise the atm temp by even one degree...and the ocean temp would be raised even LESS.  And I'll wait to discuss other supposedly lethal causes until we finish the heat part.  Do you concede the heat part is not lethal for objects impacting the ocean?  PLEASE ANSWER THIS so we can move on to smaller stuff in the upper atm.



#52 piasan

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Posted 08 March 2015 - 11:01 AM

We'll consider OTHER supposed causes of extinction AFTER you admit the heat would not be a problem, as you've claimed for 5 years.  Or is it time to get on your horse and gallop off to another topic because you don't like how this one is going for you???


There are a number of other points/claims David makes that I will address here.... as well as a new list of craters I found that is in Excel spreadsheet form and can be sorted. (My previous count of 60 craters greater than 100 mi was based on a long list that could not be sorted, so it was a hand count.

 

Just by way of making this one point.  David has a habit of bringing up other matters then complaining if I then address those issues.  For example, he brought up Dr. Brown's (so-called) "fair debate offer" then complained when I pointed out that the offer is not fair and that Brown's actions show he is not interested in a serious scientific defense of his model.

 

Then David posts on the matter of cratering and now asks "is it time to get on your horse and gallop off to another topic."   Dave.... I'm not the one opening up these other issues.  In fact, the record shows it is YOU who is doing this and I am the one responding to claims you make.  Before you again accuse me of avoiding the issue, I suggest you read rule #10.



#53 indydave

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Posted 08 March 2015 - 11:07 AM

(Pi quoting atheist Dave B.  )>>This means that the capture cross section ratio would match your (Pi's) quoted Oard value of 19 if vi  were about 16.82 km/s. It would never match your guessed value of 12.25 because the minimum value for the capture cross section ratio is 13.435  (emphasis Pi's) (their geometric cross section ratio)>>

Note that if the speed is 17km/s...which I think is what the crater size site used...then gravity has hardly ANY effect on how likely something would hit Earth.  The likelihood is NOT (as Pi said previously) "The physics favors Earth as a target by at least a factor of 5 just due to the surface area..... leave alone the 6 fold gravitational attraction the Earth has compared to the moon."  Notice HE got it wrong in his guess (5x) about surface area.  We BOTH failed to take radius squared.  So I HOPE he isn't too condescending if I missed it too.  Apparently Dave B had to point his error out to him.  Pi SHOULD have come clean to admit he too missed it LIKE I DID, but so far he has kept mum about HIS mistake, pointing it out AS IF it were only MINE.  But I was much closer to Dave B in estimating the effect of gravity, and Pi should admit that too.  He said it would be "SIX FOLD" more.  I said it would have hardly any effect, especially for larger objects.  Instead of 6-fold, Dave B said (for a speed of 16.82 km/s) the factor would take it from 13.435x to 19...which is a 1.41 fold factor...much closer to what I estimated (slightly more than 1.00x) than what Pi estimated.  Also note that Dave B said that "when the asymptotic inbound speed is enormous for objects coming into the solar system from interstellar space, and the gravity difference between the Earth and Moon becomes irrelevant."  I think DB misspoke to say "interstellar" since no one says stuff hits E or M from beyond the Solar Sytem (if you include the Oort Cloud...if it exists...as part of the SS).  Speeds of comets near Earth are much higher than 17km/s and so we would expect gravity to have virtually NO affect on stuff traveling at their speed.  So I think my answer was FAR closer to reality than Pi's was, given that we BOTH messed up by not squaring the radius to get cross-sectional area. 

 

I think it should be noted, and I expect Dave B would agree that for Earth to have a gravity effect on something (rather than the Sun affecting it) coming from far out in the Solar System, the Earth would have to be STATIONARY, rather than moving around a large circular orbit around the Sun.  How COULD the Earth move some object nearer to Earth's position in JUNE (when the hit takes place) when the object is far from Earth in DECEMBER and Earth is 186,000,000 miles to the other side of the Sun?  I would BET that neither Oard nor Dave B have thought at ALL about that in doing their calcs.  Earth's higher gravity than Moon would have negligible effects, especially at 17km/s. 

 

AND, this whole calc is only relevant in discussing objects RETURNING near E/M where there is ONE shot to hit either Earth or Moon.  The scenario Brown has involves MANY chances to hit Moon with ZERO chances of the stuff launched beyond EV to hit Earth.



#54 piasan

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Posted 08 March 2015 - 11:21 AM

Based on new data.... a list of lunar craters I found at: http://the-moon.wiki...f Lunar Craters (Go to the bottom of the page the first listing in the year 2009 is an XL spreadsheet that can be sorted by crater size) there are 95 lunar craters greater than 100 miles across.  Of these 28 are more than 300 miles; 6 are more than 500 miles and one is over 1500 miles across.

 

Using the minimum multiplier for Earth as a target, that means Earth should have encountered a minimum of nearly 1300 impacts leading to craters over 100 mi.  (recall my earlier use of 1200?); 378 impacts that would cause 300 mi craters; and 81 impacts resulting in craters over 500 miles.  We'll ignore that 1500 mile crater.

 

So, the most recent (and accurate) estimate of the number of impacts Earth should have suffered is 1300 causing 100 mi craters with 81 of those causing craters of 500 miles.

 

Of course, David thinks I'm totally unreasonable to think that if the moon takes a lot of really big impacts, the Earth .... which he admits is a much larger target ... will take some as well.  Hey David..... let's do a "turkey shoot."   Your "bulls eye" will have a radius of one inch and mine will be 3.66 inches.  Let's see who gets more hits.

 

Is anyone betting on David?



#55 indydave

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Posted 08 March 2015 - 11:33 AM

>Then David posts on the matter of cratering and now asks "is it time to get on your horse and gallop off to another topic."   Dave.... I'm not the one opening up these other issues.  In fact, the record shows it is YOU who is doing this and I am the one responding to claims you make.  Before you again accuse me of avoiding the issue, I suggest you read rule #10.>>

 

You DID "open other issues" by your suggestion that something OTHER than heat would make these impacts lethal for Noah. OBVIOUSLY I was using "gallop off" as a reference to YOUR accusation about believing Brown would do the "Gish Gallop" if he debated you.  It is not unfair of me to point out to readers that in this thread you have ADMITTED that heat of impacts would NOT be a lethal problem but then you suggested for some OTHER reason the impacts you suggest occurred would be "an extinction event."  I won't let you move the discussion to other topics (than heat) until you have relented about your claim that Brown's model would cause lethal overheating.  So quit whining about my using "gallop" (the same term YOU used) and answer my question as to whether the impacting stuff would cause overheating...and then we can move on to the 70% of reentry stuff which is smaller and loses all its kinetic energy in the upper atm.  WHAT IS YOUR ANSWER, PI???



#56 indydave

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Posted 08 March 2015 - 11:45 AM

>>Using the minimum multiplier for Earth as a target, that means Earth should have encountered a minimum of nearly 1300 impacts leading to craters over 100 mi.  (recall my earlier use of 1200?); 378 impacts that would cause 300 mi craters; and 81 impacts resulting in craters over 500 miles.  We'll ignore that 1500 mile crater. So, the most recent (and accurate) estimate of the number of impacts Earth should have suffered is 1300 causing 100 mi craters with 81 of those causing craters of 500 miles.

Of course, David thinks I'm totally unreasonable to think that if the moon takes a lot of really big impacts, the Earth .... which he admits is a much larger target ... will take some as well.  Hey David..... let's do a "turkey shoot."   Your "bulls eye" will have a radius of one inch and mine will be 3.66 inches.  Let's see who gets more hits. Is anyone betting on David?>>

Pi STUBBORNLY insists on beating up on his straw man, rather than the model Brown asserts.  Brown does NOT assert that the Moon is hit by stuff that could also hit Earth...like returning material on elliptical orbits.  That is the CONVENTIONAL view of what kind of things hit the Moon.  Brown says that stuff which goes beyond EV would have many chances to hit the Moon as it orbits Earth before the stuff is slowly pushed outward to become the asteroid belt.  ONLY the Moon could be hit by that stuff...the Earth has ZERO chance to be hit by stuff as it is being pushed outward.  ZERO.  It could be many years or decades before the stuff gets outside Moon's orbit (250,000mi past 1 AU), during which time, the Moon could be plastered by it.  NONE of that material (because it is beyond EV) could hit Earth.  NONE.  It doesn't matter what Pi hunts up on some list to change what his number of Moon craters is...he must address the model Brown asserts...or stop wasting everyone's time. 

 

So Pi...after you changed your number for the craters on the Moon (and also for how many hit Earth...to now 1300...after saying you'd use 800)...what did it change your estimate of the heating of the atm. to be?  Another millionth of a degree?  Oooooo!  Sounds SO lethal!



#57 indydave

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Posted 08 March 2015 - 01:04 PM

I think I made a valid point to say that gravity would have little effect on an inbound object until very very late on its path of hitting Earth.  This is because Earth is a very rapidly MOVING TARGET.  So it could not pull an object that is far from Earth 5 days before impact toward the position Earth would be 5 days later.  The Sun would have far far more influence on its direction.  ALL of that energy of gravity toward the earlier position would be wasted.  It would NOT be one bit more likely to hit Earth...or only the very tiniest bit more.  Again the Sun has the greatest effect of speeding it up, and if the Earth was off to the side (not in line with the Sun), adding it's gravity to the Sun's would not affect the speed of the inbound object much if any.  If it were to pull it off its trajectory toward the Sun (I doubt it would) that could LESSEN the speed the Sun gives it.  So I question if Earth's gravity in the dynamic reality of a moving Earth would have much if any ability to SPEED IT UP.  The crater calculator uses different values for "acceleration of gravity" for different targets.  Earth's is 9.8m/s2 and Moon's is 1.6.  Pi used 9.8 for his...which may seem right when figuring for Earth.  But I would say that is unfair, because much of the time just before a hit, the Earth would NOT be directly in the object's path so its gravity could not speed it up from the speed it would be due to the Sun.  The bollide is maybe days away from that position (depending on how fast the object is coming in).  So any pull of the Earth would be toward the EARLIER POSITION, not the TARGET position. 

 

At a speed of 17km/sec, gravity would have little effect on changing an impactor's TRAJECTORY, as Dave B confirmed, and at cometary speeds (50km/s) it would have far far LESS.  But acc. to the site, it CAN have an effect on energy of impact.  Using 1.6 m/s2 (Moon's) the energy goes down from 2.0e23 J to 1.25e23 J.  Pi uses the higher number (Earth's), and if my point here is INvalid, then he's got the right estimate for the energy (2.0e23 J).  If my point is right and gravity cannot speed it up until it is very close to impacting, because the Earth is a moving target...and if that were to make the effect of accel. of gravity to be less...such as like the Moon's effect...then, acc. to the site, that cuts the energy by a LOT.  To get the same energy for an impact on the Moon (with the lower factor for accel. of gravity) then the same size object must be going 78km/sec...4.59x faster!

 

I did notice what seems to be a fairly glaring error in these comments by Dave B:

 

>>My guess as to what a typical average asymptotic inbound speed would be is probably somewhere around 6 km/s since the mean orbital speed of the Earth-Moon barycenter about the Sun is about 29.8 km/s and most of the stuff hitting the Earth & Moon would probably be on comparable orbits going essentially the same way around the Sun with slightly different orbital planes, orbital radii, speeds, and eccentricities. So I would maybe expect a guess for vi of around 20% of the earth's orbital speed might be in the ballpark for the averaged capture cross section ratio then being somewhere around 52. But clearly there is quite a wide degree of latitude & uncertainty in any such estimate.>>

 

He seems here to be saying the speed of impact on the Moon or Earth would or maybe COULD be at 6km/s...which is less than half EV.  I guess he's saying that the stuff would be in about the same orbit as E/M and traveling in the same direction as Earth.  BUT, the whole idea of the conventional view is that collisions with the Moon were far in the past and had stuff coming from far OUTSIDE the E/M orbit around the Sun.  So I would hope he would agree that a 52x factor is very wildly inaccurate as a guess.  Of course the slower an object is, the more likely gravity would affect it (as I tried to persuade Pi to see, saying a faster object is LESS affected by it).  But even Pi would not be saying stuff impacting the Moon would be going THAT slow! 



#58 indydave

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Posted 08 March 2015 - 01:09 PM

>>Of course, David thinks I'm totally unreasonable to think that if the moon takes a lot of really big impacts, the Earth .... which he admits is a much larger target ... will take some as well.  Hey David..... let's do a "turkey shoot."   Your "bulls eye" will have a radius of one inch and mine will be 3.66 inches.  Let's see who gets more hits.>>

HAHAHA!...nice TRY, Pi.  It was ME who said that size (not gravity) is about all that matters.  So don't try to pull a fast one to suggest that it was ME saying that a larger target has no effect on how many hits it gets.  Stop with trying to misrepresent what I say!  I would have said right from the start that the larger one gets more hits.  What YOU were saying was that if we used iron bullets and you put a big magnet behind your target, then it would get 6x more hits than one without a magnet.  Would you like THAT to be what we bet about???



#59 piasan

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Posted 08 March 2015 - 01:24 PM

(Pi quoting atheist Dave cool.png >>

Is David now reduced to ad hominem arguments?  DaveB is a Baptist physics professor at a Christian university.  David knows this.  Last I checked, Baptists are not atheists.
 


The likelihood is NOT (as Pi said previously) "The physics favors Earth as a target by at least a factor of 5 just due to the surface area..... leave alone the 6 fold gravitational attraction the Earth has compared to the moon."  Notice HE got it wrong in his guess (5x) about surface area. 

David is correct.... I was wrong about the factor of 5.  It should have been a MINIMUM of 13.45.   Of course, David was estimating 3.66.  So, which of us was closer? 
 
 

Apparently Dave B had to point his error out to him.  

Not quite true.  I ASKED DaveB for his input.  That's a big difference between IndyDave and I.  When I'm getting in over my head, I seek out the advice of those who are true experts in physics.... often several of them.  On the other hand, Indy gets his "technical support" only from the one whose work is being questioned.  In more than 5 years, he has not once sought outside input.
 
 

Pi SHOULD have come clean to admit he too missed it LIKE I DID, but so far he has kept mum about HIS mistake, pointing it out AS IF it were only MINE. 

Hey Indy.... what do you think this means?

Pi resumes:
So, we were both partly right and both partly wrong.


 

But I was much closer to Dave B in estimating the effect of gravity, and Pi should admit that too.  He said it would be "SIX FOLD" more. 

That is not correct.  In fact, I pointed out that while Earth's gravity was 6x that of the moon, that is too much of an adjustment for gravity and immediately revised that downward.

 

I said it would have hardly any effect, especially for larger objects.  Instead of 6-fold, Dave B said (for a speed of 16.82 km/s) the factor would take it from 13.435x to 19...

Notice, Indy is claiming his estimate (3.66x) was closer than mine.... which was 20x.  His 3.66 multiplier, as it turns out is IMPOSSIBLE.  Even then, it is off from the minimum by 72%.  On the other hand, my 20x estimate was possible and was greater than the minimum by less than 50%.   By any standard of measurement, mine was closer than his (impossible) estimate.
 
Of course, Dave will now claim I'm making a "big deal" of this by my response to his criticism.  Hint:  If Dave hadn't posted his criticism, I was done when I pointed out we were both "partly right and partly wrong" and went to the 13.5x multiplier.  However, his comments created a whole new group of issues that need to be addressed in a fair and open discussion.

 

Also note that Dave B said that "when the asymptotic inbound speed is enormous for objects coming into the solar system from interstellar space, and the gravity difference between the Earth and Moon becomes irrelevant."  I think DB misspoke to say "interstellar" since no one says stuff hits E or M from beyond the Solar Sytem (if you include the Oort Cloud...if it exists...as part of the SS)..... So I think my answer was FAR closer to reality than Pi's was, given that we BOTH messed up by not squaring the radius to get cross-sectional area.

It's pretty safe to say that material arriving at such velocities is not part of Brown's model as it would escape the solar system and never return to Earth under any circumstances.  However, it is fair and reasonable to point out that DaveB was talking about only these super high velocities and not anything that approaches what would be expected in Brown's model.  In fact, Indy even points out that

 

DaveB points out that the slower an object is moving relative to the Earth/Moon, the greater gravitational influence they will exert. In fact, DaveB's best estimate is that the Earth will be a 52x larger target due to its greater gravity and the relatively low relative velocities of material launched from Earth. Once again.... when compared to DaveB's estimate of a reasonable value (52x) which of us was closer.... me at 20x or Indy at 3.66x?

By any standard of measurement, my estimate was better than Indy's.

 

I think it should be noted, and I expect Dave B would agree that for Earth to have a gravity effect on something (rather than the Sun affecting it) coming from far out in the Solar System, the Earth would have to be STATIONARY, rather than moving around a large circular orbit around the Sun.  How COULD the Earth move some object nearer to Earth's position in JUNE (when the hit takes place) when the object is far from Earth in DECEMBER and Earth is 186,000,000 miles to the other side of the Sun?  I would BET that neither Oard nor Dave B have thought at ALL about that in doing their calcs.  Earth's higher gravity than Moon would have negligible effects, especially at 17km/s.  

Whether or not the Earth is stationary makes no difference.  It looks like Dave ass-u-me(s) a distance object needs to be coming in from the opposite side of the solar system .... hence his comparison between June and December.  Apparently he has not considered it is equally likely the object is coming in from the side of Earth opposite the Sun and has not traversed that 186,000,000 miles.

 

DaveB was pretty specific on the gravitational impact at 17 km/s.  He said it would increase the effective target size of the Earth from 13.45x to 19x that of the moon.  That's pretty significant.



#60 piasan

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Posted 08 March 2015 - 02:09 PM

So Pi...after you changed your number for the craters on the Moon (and also for how many hit Earth...to now 1300...after saying you'd use 800)...what did it change your estimate of the heating of the atm. to be?  Another millionth of a degree?  Oooooo!  Sounds SO lethal!

Yeah... I got better data on the number of lunar impact craters and revised my estimate accordingly.  That's what fair, objective, and reasonable people do.  Notice, I did NOT change the multiplier of 13.5x.

 

There has been no estimate of atmospheric heating in this subject other than the one you complain about.  Understand, all of these bolides combined are a tiny fraction of the total mass that will return to Earth in Brown's model.






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