Science’s doomsday team vs. the asteroids

  • Thread starter Ivan Seeking
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In summary: Smaller asteroids. They hit us more frequently than large ones. The one that killed the dinosaurs was thought to be about 10 miles in diameter. If one that was sized one mile or less struck the earth, I doubt that it would kill all of us. In summary, an asteroid that was thought to be a false alarm has provided evidence that a catastrophic encounter with a rogue visitor from space is not only possible but probably inevitable.
  • #1

Ivan Seeking

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...The holidays and the tsunami in South Asia pushed 2004 MN4 out of the news, and in the meantime additional observations showed that the asteroid would miss, but only by 15,000 to 25,000 miles — about one-tenth the distance to the moon. Asteroid 2004 MN4 was no false alarm. Instead, it has provided the world with the best evidence yet that a catastrophic encounter with a rogue visitor from space is not only possible but probably inevitable. [continued]
http://www.msnbc.msn.com/id/7436624/
 
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  • #2
Oh, it's certainly inevitable, but it's still very improbable in our lifetime. I'm quite impressed at how close that got, though.
 
  • #3
How long do they think we have until this eventually happens?
 
  • #4
misskitty said:
How long do they think we have until this eventually happens?

Species killers are thought to be pretty rare, like million year timescales, but I don't know about the smaller ones.
 
  • #5
What do you mean the smaller ones?
 
  • #6
misskitty said:
What do you mean the smaller ones?

Smaller asteroids. They hit us more frequently than large ones. The one that killed the dinosaurs was thought to be about 10 miles in diameter. If one that was sized one mile or less struck the earth, I doubt that it would kill all of us.
 
  • #7
Oh those smaller ones. Bit off topic but related: how big are the meteroites that cause those phenomenal meteror showers?
 
  • #8
Technically, they are not meteorites unless they hit the ground, and it takes a fair sized chunk to do that. Most of what you see in meteor showers are no bigger than a grain of sand.
 
  • #9
Near Miss could be bad for us

Like ST and others, I think it very unlikely that Earth will be hit by a asteroid large enough (actually it velocity at impact is more important as energy delivered is quadratic in this variable) to abolish human life. I have not tried to do the numbers, but suspect that if a major asteroid, especially one in the ecliptic and orbiting in same sense as Earth about the sun - longer gravitational impulse) were to change Earth's orbit, it could do mankind in with greater probability.

It would not kill us directly of course. If the Earth were given an orbit as eccentric as Mars has, I think Earth would be plunged into an ice age. (This BTW is central concept of my book Dark Visitor which has sub title "The coming ice age" - An undetected black body (black hole?) of mass 2.2 solar misses Earth by 12 times the distance to the sun - much larger cross section than an "Earth hit.")

Milder, moist winters with lots of heavy "spring snows" all winter long, that do not entirely melt the following summer can send one hemisphere quickly (a few years) into an ice age. The other Hemisphere is in summer, and its evaporating oceans, supply the moisture, but life there is rough also as torrential rains wash away whole cities and little sunlight reaches the ground because of continuous cloud cover (not good for most crops). More at www.DarkVisitor.com including how to read for free.
 
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  • #10
Billy T said:
...An undetected black body (black hole?) of mass 2.2 solar misses Earth by 12 times the distance to the sun...

I just tried simulating that. A 2.2 solar-mass object passing through our solar system in the plane of the planets wreaks havoc on the outer solar system, adds a lot of eccentricity to Mars' orbit, but leave Mercury, Venus, and Earth virtually unchanged.

Depending on starting conditions, the outer planets can be stripped from the solar system, be forced into orbits that cross each other, or be forced into comet-like orbits. Mars can be forced into an Earth-crossing orbit which would ultimately affect Earth.
 
  • #11
Trouble is, Bill_T, we have no information on which to base a prediction on the likelyhood of such an event (besides the zero data point: the fact that its never happened before).
 
  • #12
Has anybody noticed that the "near miss" could intersect the orbits of geostationary satellites? Oops. Also in the linked article, there is a statement about the possibility that the near miss could put the asteroid into a resonance with Earth that could increase the chances of a future collision. It may be a good idea to plan a mission to give that rock a rocket ride into the sun.
 
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  • #13
Doomsday Drama...

A meteorite struck at Meteor Crater, Arizona (the Barringer Crater) about 49,000 years ago leaving a crater 1200 m in diameter and 200m deep. Impacts like this one, can occur every 1000 years. Barringer Impact Energy = 3 Megatons TNT

At the very least, before it is done, the human race can expect to lose dozens of cities containing millions of people to 'natural space events'. Also, meteor events rarely arrive as a 'singlet' event, but rather as a 'storm' or 'shower', an entire planetary bombardment of hundreds to thousands of impacts containing several megatons of energy in each.

Asteroid 2004 MN4 is a "regional" hazard -- big enough to flatten Texas or a couple of European countries with an impact equivalent to 10,000 megatons of dynamite -- more than all the nuclear weapons in the world. Even though it will be a near miss in 2029, that will not be the last word.

The human brain wouldn't grasp reality until it had somewhat more direct evidence.
- planetary scientist Clark R. Chapman of the Southwest Research Institute

"The good news is that comets represent 1 percent of the danger," said Donald K. Yeomans, who manages NASA's Near-Earth Object Program at the Jet Propulsion Laboratory. "The bad news is that should we find one, there's not a lot we can do about it. . . . We detect them only nine months from impact."

This is basicly the ground line, if an extinction level asteroid were detected, all the human race could do, is celebrate its own extinction, like it was...2029.

Detecting an extinction level event nine months prior to impact, only means that there is only plenty of time to get a great seat and popcorn for a spectacular light show that would stop the ticker on the entire human race.


Reference:
http://www.washingtonpost.com/wp-dyn/articles/A38306-2005Apr8.html
 
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  • #14
Orion1 said:
Detecting an extinction level event nine months prior to impact, only means that there is only plenty of time to get a great seat and popcorn for a spectacular light show that would stop the ticker on the entire human race.
Maybe we need to boost a few empty rockets into space and fuel them up in orbit before stationing them at the Lagrange 4 and 5 points, just to have them ready for that 9-month warning. That might not be enough time to get the craft into a usable intercept path, but its a heck of a lot better than we have now.
 
  • #15
tony873004 said:
I just tried simulating that. A 2.2 solar-mass object passing through our solar system in the plane of the planets wreaks havoc on the outer solar system, adds a lot of eccentricity to Mars' orbit, but leave Mercury, Venus, and Earth virtually unchanged.

Depending on starting conditions, the outer planets can be stripped from the solar system, be forced into orbits that cross each other, or be forced into comet-like orbits. Mars can be forced into an Earth-crossing orbit which would ultimately affect Earth.
For several reasons, I made the "dark visitor" approach from the north polar region, on trajectory nearly perpendicular to the ecliptic. One reason being that an approach nearly perpendicular to the ecliptic tends to produce little relative motion between the planets longer (while dark visitor is still far away) and thus is less disturbing and harder to detect longer.

I did not do your "in ecliptic" pass, but think you are surely correct.
 
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  • #16
russ_watters said:
Trouble is, Bill_T, we have no information on which to base a prediction on the likelyhood of such an event (besides the zero data point: the fact that its never happened before).
I tend to agree, but suggest in book and more strongly at www.DarkVisitor.com that the perturbation of Neptune that lead to Pluto's discovery definitely was not caused by Pluto, as originally believed. (Pluto is smaller than the moon, and must have several Earth masses to have been responsible for the perturbation.) It could have been caused by a massive unobserved object (a "dark visitor") passing outside of the solar system. I am not claiming that it was, only that this could have been the cause of both the perturbation and Pluto's tilted orbit plane.

How can you say: "fact that its never happened before"?

I at least have some bases for suggesting that it may have happened in the 1920s. I also argue that if a stellar core black hole did cause the perturbation, then it is quite possible that it was one of a pair. - Most stars do form in pairs.

Furthermore, most of first few generations of stars (which formed and died before our sun was even born, back when the universe was much smaller) were much larger and both members of the pair quickly (in comparison with the sun's life time) died and left gravitionally bound black holes behind. Because there were several generations of these black-hole pairs forming stars, it is at least arguable that there may be more black-hole pairs than all the currently luminous stars. (See next paragraph for addition increase in their numbers.)

My postulated 2.2 solar mass dark visitor, is on more weak generally accepted grounds because it is so small. I think that the final collapse of an iron-core star that forms a black hole is far from the nice symmetric event treated by mathematicians. I think it is the source of much smaller iron masses that do not be become black holes. Even those which we call "iron meteorites when they hit Earth. If this is even partially correct, then a star of 20 to 50 solar masses might be able to also produce several small black holes, some of which escape from each other (in the "hypernova" implosion)and some of which decay into one by gravity radiation, but most are probably still gravitationally bound together at this stage of the universe.

It is all very complex, but I don't think it is necessarily false in any aspect as a possibility. Since I can at least point to the possibly that one passed less than 100 years ago, (Neptune's unexplained perturbation), I think your support for your statement that "it never has happened" is weaker than mine that only suggests that it cold have and we don't know how probable it is.
 
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  • #17
SpaceTiger said:
Species killers are thought to be pretty rare, like million year timescales, but I don't know about the smaller ones.

I am pretty sure that the number of expected Tunguska sized events [per unit time] has been upped in recent years. I know that at least one noted astronomer has made this statement in the sci/tech media.

One big concern here is, or at least some years ago was, that a meteor or comet strike could trigger an accidental nuclear war.
 
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  • #18
Ivan Seeking said:
One big concern here is, or at least some years ago was, that a meteor or comet strike could trigger an accidental nuclear war.

Yeah, that would really suck. I don't know enough about the topic to say anymore, but fortunately, at the moment, there's only a small fraction of the Earth on which that would be a problem.
 
  • #19
Billy T said:
How can you say: "fact that its never happened before"?

I at least have some bases for suggesting that it may have happened in the 1920s. I also argue that if a stellar core black hole did cause the perturbation, then it is quite possible that it was one of a pair. - Most stars do form in pairs.
It happened in the 20s? AFAIK, the Earth (or any other planet) didn't get flung out of its orbit in the 20s, like you're "predicting"...
It is all very complex, but I don't think it is necessarily false in any aspect as a possibility. Since I can at least point to the possibly that one passed less than 100 years ago, (Neptune's unexplained perturbation), I think your support for your statement that "it never has happened" is weaker than mine that only suggests that it cold have and we don't know how probable it is.
Sorry, but your burden of proof is far more stringent than just the fact that we don't know what is perturbing Neptune's orbit. You're pulling things out of the air that you have no reasonable basis for. Besides that, you're wrong about your understanding of some things: like what's going on with Neptune's orbit. It wasn't changed in 1920 in any meaningful way - its just irregular (and as far as we know, always has been). For starters, it was known to not exactly fit predictions as early as 1905 and the irregularities continue today. And the irregularities are very small. They do not support the hypothesis that an object flew by and perturbed it in a single, isolated event.
 
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  • #20
SpaceTiger said:
Yeah, that would really suck. I don't know enough about the topic to say anymore, but fortunately, at the moment, there's only a small fraction of the Earth on which that would be a problem.

Of course, a hit of that size [Tunguska] anywhere else would probably generate a 500 foot tele-tsunami. :yuck:
 
  • #21
russ_watters said:
It happened in the 20s? AFAIK, the Earth (or any other planet) didn't get flung out of its orbit in the 20s, like you're "predicting"...
That is a gross exageration - the change in Earth's orbit I calculated (increase in the eccentricity to 0.0836 from current 0.0171) has hardly "flung {Earth} out of its orbit." In fact, Earth in its new orbit is still less eliptical than Mar's current orbit! You should note that a 2.2 solar mass object passing thru ecliptic 12 AU from Earth applies only 2.2/144 or 1.5% sun's continuous force on the Earth, and then only very briefly at the closest approach point on its open trajectory back into deep space.

If you are going to attact the possibily as unrealsitic flinging the Earth out of its orbit, this way I ask:
Has Mars been flung out of its orbit? (By some "dark vistor" that passed recently - Orbit not yet recircularized.) Be consistent - You can not both claim it never happened and ignore Mar's current orbit, which by your standards has be "flung out of its orbit" by something.

russ_watters said:
Sorry, but your burden of proof is far more stringent than just the fact that we don't know what is perturbing Neptune's orbit. You're pulling things out of the air that you have no reasonable basis for. Besides that, you're wrong about your understanding of some things: like what's going on with Neptune's orbit. It wasn't changed in 1920 in any meaningful way - ...
In at least one way the perturbation to Neptune in the 1920s certainly was "meaningful." - It caused Percival Lowell to establish (fund) the observatory at flagstaff AZ, now named after him, and to hire people to specifically search his predicted location for "Planet X" with a new telescope designed specifically for this purpose.

He also had developed for the search the "flicker detection system" (where two photos of star fields, taken some days or months apart, are alternately displayed rapidly - new astronomic technology that has proven to be very useful). Pluto was actually discovered on a sunny Arizona afternoon, with this equipment, when one very faint "star" wiggled slightly in the display.

Thus, I am not:
"pulling things out of the air that you have no reasonable basis for"
I am just telling some factual history, and noting that the unexplained 1920s event had many astronomers excited, perhaps wrongly so. I am not trying to prove anything, so there is no "burden of proof" on me.

You are the one who, IMHO, has made an unsupported claim. ("It did not happen.") and I again ask: How do you know that an unseen (because it was not reflecting sunlight) small black hole (or other very dense object of very low reflectivity, perhaps even an clump of "dark matter") did not pass by the solar system?

How far from the solar system it would need to be depends on its mass, but as the effect is essentially over, the required mass is not very large, but large enough and far enough from most planets so that only the then outer most known planet (Neptune) was perturbed enough to get astronomers excited and spending lots of money to be the discover of "planet X" which was widely discussed in the literature. If it happened, it was probably a few solar masses and passsing in the sector both Pluto and Neptune were in back then, but closer to Pluto, probably by at least a factor of two. (I have not done any calculations about this, so I am just guessing.)

Again I am only stating it is possible that then unknown Pluto had its orbit plain slightly tilted and Neptune was perturbed more than it is today by the passage of some unseen "dark visitor." Why do you deny this as even a possibility - "It did not happen"? As I stated in my first post replying to you, I am also inclined to agree (it did not happen), but I am not able to exclude this "dark visitor passage" completely.

This 1920s history, combined with the facts (as presented in last post and at www.DarkVisitor.com) about the existence of many small black hole pairs, arguably more than all the current luminous stars (also more than all the grains of sand on all of the Earth's beaches!) gave me basis for my scary story of a coming ice age, which is due to a very slight change in Earth's orbit as the second, smaller member of the pair cuts, nearly perpendicularly thru the ecliptic in late 2008 and makes Earth's orbit nearly as eccentric as Mar's current orbit - again this can in no way be described either as a "prediction" or as flinging Earth out of it orbit! The possibility of a pair of objects passing thru the plain of the ecliptic in 1920 and 2008 is highly improbable, but will surely happen someday.

You are being unreasonable harse in you unfounded assertion that it did not happen in 1920s. I am only using the possibility to scary some readers who are bright, but currently totally uninterested in science. (In the hope they may become so and help prevent the US from becoming an insignificant power in the next few generations as Asian economies take over. You should help this cause - not attack it.)

Did you see the Physics Today March 2005 issue? On pages 29-31, you will see that my concern about the US decline are also not "pulled out of the air", but are also "historic facts." Technological leadership has already been lost to Asian nations and if current trends continue, scientific leadership will be lost in about a generation. For example, in that very respected journal you will learn:
(1) US undergrad degrees awarded in natural sciences are 5.7/100 (lowest ratio of any nation listed) but in South Korea the ratio is 11/100.
(2) In four year study period ending in 1998, the number of Asian students choosing to get Ph.D.s in their own country doubled, but those coming to US for one dropped 19%. (Because of 9/11 changes change in US immigration rules, it is probably "tripled and down 75%" now. - Even some older, good, badly needed, Asian physics professors are "going home" to help with the development of "their homeland" - I know one who did. - if it is not already, the "brain drain" will soon be a US problem. US can't even pay for fixing gyroscopes on Hubble.)
(3) US share of global high-tech exports fell from 31% to 18% while Asian nations nations increased form 7% to 25%. (Last data in the study period was from 2001 - this is also much worse today as you can see in the growing balance of payments deficit.)
(4) US scientific publications (many with Asian authors, thinking about "going home") increased 13% between 1988 and 2001. In same period, published asian based research increased 492% !

Don't get me wrong - I admire the hard working asians - some were among my best students. US students had better wake up soon to realize that without a greater interest in science, when they graduate as lawyers, wall street agents, etc. the salaries that lured them to those choices will no longer be there. - Most exportable jobs will have gone to Asia. They may need to settle for a non-exportable job like cutting someone's hair or selling fast food.

All my grand children live in the US. Time is short. Things must change. US is going down the tubes and is not aware of it. I used the physically possible hypothesis of a 1920/2008 black hole pair to write a scary recruiting tool for science students. Unlike most science fiction, book Dark Visitor is based on history and real scientific possibilities. It teaches a lot of science, but naturally woven into the story, because I do not want to repel my target reader (who never would knowningly open a science book). The first four chapters are mainly historical, about the background of the principle characters, the science slowing increases as astronomer "Jack" explains to his historian friend "Billy T" (book's author) how and why the only the Northern Hemisphere will be plunged rapidly into and ice age beginning in winter of 2008/2009 (Washing DC gets 77 feet of snow that first winter and more each year thereafter until the the oceans surface is below the edge of the continental shelf again. - As the albedo is increased by the growing ice sheet, things get worse more rapidly - NW US and Western Europe have ice sheet coverage more than a mile thick by end of century. Ports are useless in less than a decade - ice stored on land quickly stops oil importation globally.

At the site you can learn how to read for free. Recurting science students is my objective, not profit.
 
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  • #22
Billy T said:
That is a gross exageration - the change in Earth's orbit calculated (increase in the eccentricity to 0.836 from current 0.0171) is hardly "flung out of its orbit" In fact Earth in its new orbit is less eliptical than Mar's orbit!
Did you do any calculations on that? tony873004 says he ran a simulation on your scenario and it would knock all the outer planets out of the solar system. Regardless, there has never been an event that has had a noticeable effect on the Earth's orbit.
If you are going to attact the possibily as unrealsitic this way I ask has Mars been flung out of its orbit?
Obviously not - hey, its your claim, not mine.
In at least one meaningfully way the perturbation to Neptune in the 1920s certainly was "meaningful"...
You are characterizing Neptune's irregular orbit as a single event. That is not correct. (as I said above)
Thus I am not "pulling things out of the air that you have no reasonable basis for" - I am just telling some factual history...
See above: your history is factually wrong.
I am not trying to prove anything, so there is no "burden of proof" on me.
You made a very specific prediction. The burden of proof is the weight given the prediction (or, 'is it worth buying your book?'). So far, it looks like handwaving and empty, baseless speculation. Saying it isn't a claim only makes it sound like you're trying to avoid substantiating it.
I again ask how do you know that an unseen ( because not reflecting sunlight) small black hole (or other very dense object of very low reflectivity, perhaps even an clump of "dark matter") did not pass by the solar system?
Simple: no event was witnessed. No change in Neptune's (or any other planet's) orbit was detected. Again, you misunderstand the history.
Again I am only stating it is possible that then unknown Pluto had its orbit plain slightly tilted and Neptune was perturbed more than it is today by the passage of some unseen "dark visitor" which passed outside of the solar system in the general sector of the sky in which Pluto and Neptune were both in at the time. Why do you deny this as even a possibility - "It did not happen"?
It is possible that there is an invisible, purple elephant in my garage. Do you deny this possibility? It has exactly the same direct evidence supporting it as your claim (nothing).

One clarification I need: is your book intended to be a work of fiction?

Edit: also, in your website the claims are far more specific and strong:
The approaching Dark Visitor (probably a small black hole) is known from an analysis of very small perturbations observed in the Pluto's orbit. [emphasis added]
That's a lot different than what you say above - a strong, positive claim. Its a lot tougher burden of proof than the 'but you can't rule it out, can you...?' thing you're saying above.
 
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  • #23
Billy T said:
Technological leadership has already been lost to Asian nations and if current trends continue, scientific leadership will be lost in about a generation.

That phrase always makes me gag. There's no reason that we should expect a simple linear extrapolation of a developing nation's progress to continue to the point where it surpasses everyone else. Furthermore, I don't have a very high opinion of the approach Asian nations take to education. Part of the reason they have higher stats in science is that they completely deemphasize (and sometimes even ridicule) other academic pursuits. An ex-girlfriend of mine from India says everyone made fun of her and mocked her when she said she wanted to work in the humanities, but she would win every poetry competition she entered. So, she came to the US to study english at Princeton. A year or two later, she went back to India and worked for a marketing firm and helped to develop one of the most successful ad campaigns in India's recent history.

The single-minded approach to education in Asia also produces very poor researchers, it seems. The people who run the department I work at told me they had to practically stop accepting grad students from Asia because, despite extremely high test scores, they would always come here be completely ineffective at research. That's not to say that there are no good Asian researchers or that American dominance will continue indefinitely, but your above arguments give only one side of the story and I think things are much more complicated than you let on.
 
  • #24
SpaceTiger said:
That phrase always makes me gag. There's no reason that we should expect a simple linear extrapolation of a developing nation's progress to continue to the point where it surpasses everyone else. Furthermore, I don't have a very high opinion of the approach Asian nations take to education. Part of the reason they have higher stats in science is that they completely deemphasize (and sometimes even ridicule) other academic pursuits. An ex-girlfriend of mine from India says everyone made fun of her and mocked her when she said she wanted to work in the humanities, but she would win every poetry competition she entered. So, she came to the US to study english at Princeton. A year or two later, she went back to India and worked for a marketing firm and helped to develop one of the most successful ad campaigns in India's recent history.

The single-minded approach to education in Asia also produces very poor researchers, it seems. The people who run the department I work at told me they had to practically stop accepting grad students from Asia because, despite extremely high test scores, they would always come here be completely ineffective at research. That's not to say that there are no good Asian researchers or that American dominance will continue indefinitely, but your above arguments give only one side of the story and I think things are much more complicated than you let on.
I think you have some good points. I would agree with much of what you said, and could add that in at least the case of India, the "computer science" graduates are distorting the data (But perhaps that is where the good research will be done in simulations the next generation, not the lab)

One of my Indian student (Pandy by name) was extremely bright, but totally inept in the lab. One day a knob fell off a power supply. Pandy just shrugged his sholders and stopped. - it was fate, unfixable. I doubt, however, that you would deny that India has produced some of the world's best mathematicians and continues to do so. Personnally, I think this field and computer science may be "the research areas of the future", but I am not good in either, so what do I know.

I also want to note as quicky as I can that my text quoted below by Russ -water was from the original post, before editing errors and making minor changes. The number 0.836 should have been 0.0836 as it now is. The erroneously typed value would kill us all in a few months. I will probably reply to him soon.
 
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  • #25
Billy T said:
I doubt, however, that you would deny that India has produced some of the world's best mathematicians and continues to do so.

Of course I do, and my opinion is not meant to be racist or even ethnocentric. Rather, I just thought your statistics were poorly representing the real situation. Asia is good at producing a certain kind of thinker, but America is good at producing a different kind. Rather than one overtaking the other, I believe both will have a role to play in the future development of science.
 
  • #26
russ_watters said:
Did you do any calculations on that? tony873004 says he ran a simulation on your scenario and it would knock all the outer planets out of the solar system.
Yes a finite time step model solution of the three body problem, but I falsely assumed a circular orbit initially for Earth. The hardest thing for me to do was convert the readly available data about where the planets are seen to be from Earth into absolute positions in space. The trajectory of the dark visitor assumed passes well inside and behind Pluto's orbit. Pluto slows down and falls much as Tony873004 describes, but it still never becomes "Earth crossing." The interesting planet is Saturn as it can also be 12 AU from Earth, like the Dark Visitor. Jack, the astronomer is not yet certain about the approach velocity (Larger mass and faster approach have roughly the same effect on the current / future perturbations as smaller mass coming more slowly.) Jack's fit to his observed data on residual perturbations of Pluto do not permit these two variables to be well separated yet. - he is busy now looking for gravitational lens effect on background stars - that is why he asked his historian friend, Billy T, to "SOUND THE ALARM" instead of writing the book himself.

Billy T needs a lot of help with the physics and climate effects - a vehicle to teach without being too obvious that I am doing so as they interact in the story. :wink:

Tony873004 put the dark visitor by the planets in the plain of the ecliptic. For many reasons, I passed it nearly perpendicularly thru the ecliptic. (Main one being I wanted the effect on all the planets and sun to be approximately the same - accleration towards the dark visitor with little relative change in their orbits until the dark visitor got close to the solar system.) I never ran his case, but think he is correct. I hope he will repeat a run with a trajactory that is perpendicular to the ecliptic and tell us his results.
 
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  • #27
Sorry I have now tried several ways to post here for your convenience, but failed. I may try again later. The best way for you to see the calculation results quickly now is to go to sub page called "graphical results" from home page of www.darkvisitor.com
 
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  • #28
SpaceTiger said:
Of course I do, and my opinion is not meant to be racist or even ethnocentric. Rather, I just thought your statistics were poorly representing the real situation. Asia is good at producing a certain kind of thinker, but America is good at producing a different kind. Rather than one overtaking the other, I believe both will have a role to play in the future development of science.
They are not "my statistics" not even Physic Today's. It was a "high-powered" task force metastudy - a collection of many other studies. I did not Xerox the first page so can't give the name, but think one of the task force leaders was David Peyton, Director of Technology for the National Ass. of Manufactures. Intel's Comer is also mentioned on the pages I did xerox.

One summary given is: "We have downward trends in participation of American citizens in science and technology while at the same time there is a dramatic increase in [S&T] competition from elsewhere. The handwriting is on the wall and in the statistics."

Thus I am not just extrapolating the Asian growth rates, but the downward US trends are also a factor - that is you are right it is a complex problem.
 
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  • #29
russ_watters said:
...One clarification I need: is your book intended to be a work of fiction?
Edit: also, in your website the claims are far more specific and strong...
Let me clarify the situation: The website is for my target reader, expressing my concern about America's future and trying to interest the visitor in the book by giving a few facts probably not know to the visitor that may scare him/her. It does not clearly separating fact from improbable possibilities. I don't think there is anything there that is contra to physics, but some areas are speculative, but within the bounds of accepted physical theory, and very improbable without explicitly admiting this. (I don't remember everything that is there -a friend set it up for me as I have zero ability in this area and nothing has every changed there. He still owes me the fifth page, but still I owe him some more translation into English.)

My target reader will never be reading anything here at Physicsforums, so I can be more candide here. (He/she is smart but only visits at business and legal websites that I know nothing about.) I am trying to scare the target reader enough that he/she may want to learn a little science. - To see if it is possible that an ice age may be the most important thing to plan for. (I recognize that few will be gullible enough to believe and ice age is their immediate future on bases of what is there.) Unfortunately, some posters here, have taken what is there as serious "predictions" despite what is there explaining the book's purpose and the posts a I have made here that are very clear that the rapid ice age onset is highly unlikely, only "physically possible" if a "dark visitor" should come by.

Thus the book is presented as if it were a factual prediction by astronomer Jack. It is a work of fiction (as far as I know, highly improbable to be fact.) but I did not want it to contain false physics, etc. I am trying not only to scare, but to show how interesting science can be. In many ways I am trying to do what Orsen Wells did with "war of the worlds" radio broadcast. If you don't know about it, See:
http://history1900s.about.com/od/1930s/a/warofworlds_2.htm
The major differences between Wells and me are:
(1) He was a creative artist - I am a retired professor, who never wrote any literature, and probably don't do it well. (Judge for your self- one subpage of the site, gives sample text.)
(2) He did not limit himself to physically possible processes (although his heat ray weapon does anticipate the gas dynamic LASER some "Teller types" want to deploy) but I do so limit myself.
(3) His intention is unknown to me, but I am trying to steal back some bright students from the business and legal worlds.

The idea that we must fight back came to me while reading a story in my alumni magazine. It told about a grant of real money had been given experimentally for students to invest in stock market. (They could keep half of the profits and did not need to make up any losses out of pocket.) The thing that made me mad was the final paragraphs. They told of the experiment's success - almost everyone of the students who had participated, some from the physical sciences, and had now graduated were now working (or in law or graduate business school) directly in some financial firm or job related to corporate finance!

I may be old and feeble now but at least I am trying to "counter punch." Do what you can - it is your future.
 
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  • #30
Mars' eccentricity can be explained by the presence of Jupiter. In a simulation, I corrected Mars' orbit and made it round. Within a few million years, it was back to elliptical. Re-running the simulation after deleting Jupiter, Mars' eccentricity does not fluxuate nearly as much.

Jupiter also causes the opposite. Sometimes it temporarly rounds out Mars' orbit. It does this to Earth too, but to a much lesser degree.

A simulation where the dark visitor approaches from above yields similar results. In this case, Saturn, Uranus, Neptune & Pluto were ejected, Jupiter was forced into an elliptical orbit with a high inclination. Mercury, Venus, Earth and Mars were virtually unchanged.

Here's some screenshots:
http://orbitsimulator.com/orbiter/before.GIF The solar system before the arrival of Dark Visitor
http://orbitsimulator.com/orbiter/during.GIF Dark Visitor (purple object passing vertically through the solarsystem) plays cosmic bowling with our planets.
http://orbitsimulator.com/orbiter/after.GIF Mercury-Mars are virtually untouched. Jupiter has high eccentricity and inclination. All other planets are stripped from the Sun.
 
  • #31
tony873004 said:
...A simulation where the dark visitor approaches from above yields similar results. In this case, Saturn, Uranus, Neptune & Pluto were ejected, Jupiter was forced into an elliptical orbit with a high inclination. Mercury, Venus, Earth and Mars were virtually unchanged...
Thanks - very interesting - pretty pictures. I wrote simple three-body finite-time-step code in a spread sheet and could not follow full orbit year beyond a few Earth years, but Earths orbit closed very well when code was tested with DV's mass set to zero - graph overlapped so well I could not see the starting point or final points and numerical data fit ellipse well. (Total run time was limited - not enough lines "copied down" in spread sheet and time step was limited to about 4 days max, even though each step was computed twice in same line of code - forces acting at first results for end of time step position were averaged with the forces at the start of time step to get "effective average force" acting during the time step. - I know there are much better ways to increase time step size, but I wanted to keep every thing very simple so my target reader could follow it all. I also wanted to use the spread sheet's automatic graphing capacity.)

My graphs and data for Pluto were thus limited to the begin of its fall towards the sun. I fit ellipse thru two computed points to get Pluto's apogee and perigee -not a very good method, in view of your statements as they don't even exist! I did not actually compute anything for any planets except Pluto and Earth. The entire code, step by step explained, prints in less than three pages of the book' appendix 2 - ridiculous by your standards!

Please keep in mind that I never give the initial conditions used exactly and am not trying to do anything but interest a person not currently interested in science to be come so. I wanted to give a flavor of the method of science, not do any. I set the miss distance to 12AU so I could go into details about gravity gradient ripping Saturn apart, if the timing was such that they got close.

I am glad you confirm that the change in Earth's orbit is very slight. Can you easily extract the new eccentricity? How does it compare to my 0.0836? I can't be sure, because of the perspective in your figures, but looks like from the curvature of the purple dark visitor line that your 2.2 mass is going significantly slower than mine, so I expect that even though you don't see much effect on Earth, your computed change in eccentricity is greater. My dark visitor is initially taking approximately 10 days to close on the sun by 1AU. What speed did you assume (before solar acceleration is significant)? I am nearly at a speed where the "impulse approach" is meaningful. For reasons I will not go into here, but will tell in private msg, I can't give its absolute speed relative to "fixed stars" or sun's initial position.

Again thanks - BTW I have read (and repeated here) that even the solar system is chaotic. How far into the future does one need to go to see an object in it signficantly change its orbit, or does that never happen unless a few of the larger asteroids (orbit crossing bodies) are included?
 
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  • #32
Orbital elements and perihelion and apihelion values are given by the program's menu View >Orbital Elements box. The Earth is virtually unchanged, its eccentricity being about 0.016 both before and after Dark Visitor passed through. Its perihelion / aphelion distances both before and after are 147000000 / 151000000.

But there countless ways you could set up the starting conditions. An object that passes 12 AU from the Earth can pass anywhere between 10 - 13 AU from the Sun depending on Earth's position during the close encounter. I would tend to think that your new figure of 0.0836 is a bit high, but it would be necessary to run the simulation many times with many different starting conditions to rule it out. You can try it youself ( www.gravitysimulator.com ). Send me an e-mail if you need help with starting conditions.

Making DV pass closer to the Sun and not so close to Earth would yield large changes to all the planets' orbits, regardless of their starting positions, as the Sun is yanked from its position.

I ran a few different "in-plane" simulations with different starting conditions and got different results such as which planets were ejected, etc. but the common theme was that the inner solar system (mercury - earth) was left alone, while Mars was affected, and Jupiter and beyond were greatly affected.

In the particular simulation in the pictures, DV's closet pass to Earth was 9.8 AU, slightly closer than your 12 AU simulation. It's just hard to exactly nail down the starting conditions for a perfect 12 AU pass.

Dark Visitor's solar velocity at infinity =~27km/s

The solar system is chaotic, but the chaos tends to show up in the smaller details. For example, it would be difficult to predict where Earth will be in 1,000,000 years. It's eccentricity is going through small periodic changes. So are its inclination, Semi-major axis, period, etc. But on a larger scale, it is safe to say that the Earth will still be orbiting the Sun at 1 AU +- a very small tolarance in an orbit that is close to circular, and close to the plane of the other planets, even though we don't know where in its orbit it will be. It could be on the other side of the Sun compared to where a prediction would place it, which is a huge change in position of about 2 AU. But the size and shape of the orbit won't change that much.

The same is true for all the planets. A billion years from now, it would be impossible to say where the planets will be, but the sizes and shape of the orbits will be very similar to what they are today.

Asteroids have insignificant effects on the size and shapes of the planets' orbits. But they will introduce chaos that will make it impossible to predict the exact locations of the planets in millions of years. It's like the butterfly effect.
 
  • #33
Chronos said:
Technically, they are not meteorites unless they hit the ground, and it takes a fair sized chunk to do that. Most of what you see in meteor showers are no bigger than a grain of sand.

They are that small! If they are so tiny why do they make the bright streeks you see in the sky? Wouldn't they burn up in the atmosphere so quickly you wouldn't see them?
 
  • #34
They're moving very fast and have a lot of kinetic energy. Kinetic energy is 1/2 * mass * velocity^2. So velocity is much more important than mass. They make bright streaks because they ionize the air as they wizz through it.
 
  • #35
Billy T said:
Thanks - very interesting - pretty pictures. I wrote simple three-body finite-time-step code in a spread sheet and could not follow full orbit year beyond a few Earth years
So what you're basically saying is that you wrote a crappy program with a number of essentially crippling limitations, and then went on to write a crappy book about the "data."
I wanted to give a flavor of the method of science, not do any.
Well, that seems like an incredibly stupid way to teach people. I don't suppose you can describe any demonstrated advantages to your "teach-by-stupidity" pedagogy?

We've already talked about this to great extent, Billy T. It should have already been clear to you, but I'll say it again; if you ever, ever make another post on this site about black holes or dark visitors or any other such nonsense, I personally guarantee that you will never be permitted to post here again. Consider yourself thoroughly, inexorably debunked.

- Warren
 

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