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Jupiter, Earth's savior? (Read 15309 times)
shellandtube
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Jupiter, Earth's savior?
09/15/07 at 03:52:09
 
I remember seeing a program that suggested that the Earth was protected from asteroid collisions due to the gas giants. I decided to test this theory by creating a slightly scaled down version of the solar system with 2 earthlike planets in close orbit to a 0.1 solar mass star and 2 jupiterlike planets further out. I then created 100 asteroids with eccentric orbits such that very few (approx 5) were "earth crossing". I then ran the simulation with a 512 timestep and found that after 200 years 2 were captured by the GG's, 9 had been ejected and the majority of the remaining asteroids where now in orbits that where highly eccentric and very short period. That is to say the were earth crossing and no longer crossed the orbits of the gas giants. From looking at the masses of the planets and the sun it would appear that the vast majority of the collisions were from asteroids impacting the sun. This would obviously mean that they crossed the orbit of the earthlike planets. This would suggest that they increase the chances of earth impacts? Over a longer period of time those asteroids that haven't impacted the sun and no longer are significantly affected by the GG's are now fair game for the earth! So what I have found is the idea of protection is false. Or is my simulation too innacurate/unreliable?
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #1 - 09/15/07 at 07:05:40
 
I recently saw an article about this item , here's a link .  
http://space.newscientist.com/article.ns?id=dn12532
Jupiter may indeed have a negative influence upon the Earth treads
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shellandtube
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Re: Jupiter, Earth's savior?
Reply #2 - 09/15/07 at 10:41:34
 
Cheers frank. I reran the simulation paying attention to what was happening. The interactions with the GG's caused the asteroids to loose momentum and therefore peturbed the orbits such that they headed for the dominant mass of the system ie the sun. Depending on how much momentum they lost they either entered into small period orbits or collided with the sun. Under certain conditions they were captured by the larger of the GG's but quite often they were later ejected from the solar system. Due to interactions with the other gas giant working on a similar principle as above.  The outer GG (lowest mass) slowed them down allowing them to become more eccentric with respect to the larger inner GG and were then ejected.
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #3 - 09/26/07 at 11:34:33
 
Does Jupiter protect us against collision from asteroids ?  
I came up with the following sim , not giving an answer to the question above , but resulting in nice images ...
Supose the solar system is surrounded by a ring of asteroids , lets say 360 , one asteroid every degrees .  
Position them at 32 AU from the sun ( about the orbit of Pluto ) .  
As they are in rest initially they will be pulled inwards by the sun , accelerating and will cross Neptune , Uranus ; Saturn , Jupiter , Mars ...to reach Earth .  
Will they hit Earth ? What's the influence of Jupiter ?  
The sim in annex shows the end phase of the simulation as the asteroids have come close to Earth after a journey of several years having crossed the outer planets ...
Ill post an animated gif of this sim .
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #4 - 09/26/07 at 11:41:12
 
Heres the animated frame of the above simulation , covering the period before close approach to Earth .  
Screenshots were made initially every 120 days .  
As the asteroids come closer the screenshot rate as well as the zooming was increased . May be somewhat confusing . Sad  
Interesting is the following : watch how the asteroids are initially close to Neptune ( at 9 o clock ) . Does Neptune influences their motion ? Seems not to be , but watch till the end...
Also Jupiter seems to influence the orbits .
I'll post the end of the simulation .
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360Asteroids.gif
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #5 - 09/26/07 at 11:57:42
 
The picture herenunder represents the end of the simulation , starting at the end of the previous picture .  
The initial circular confuguration of the bodies is now heavily disturbed at 9 'o clock (Neptune ) and at 6 'o clock ( Jupiter ) .  
All the asteroids are now heading towards the sun ( I don't think one has collided with the outer planets , no does one collide with Earth  ) .  
The picture hereunder gives only an impression of the movement . Running the sim makes much more fun.  
It is really amazing to see how the asts are "sucked in" by the sun , one after another like a chain .  
Only 5 of the original 360 bodies survive .
It seems to be so that the asteroids that survive are those which were disturbed ...They stay alive and stay as a threat .
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360AsteroidsEnd2.gif
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #6 - 09/27/07 at 10:48:18
 
Another way to get an idea about Jupiters influence on asteroid orbits ...
In the sim hereunder 500 small objects were created in a circular path around the sun within Jupiters orbit +/- 1% . So they appear as a circle . Jupiter is somewhere in the middle of them , originally at about 12 'o clock .  
Will Jupiter catch them ? Will they be ejected or bound as a moon to Jupiter ?  
The picture herunder gives the first thirty years of the life of this asteroids .  
 
It's remarkable that Jupiter creates very quicly a "gap" in the ring , some asteroids are pulled outwards , others are driven inwards , others tend to orbit Jupiter .  
I guess that after longer  time Jupiter will be able to create Trojans or will be puliling the asteroids into horseshoe orbits .
The asterods driven inwards yet remain at a safe distance from the inner planets .  
( Question : is it possible here to post 2 files ie. also the .gsim file ? )  
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« Last Edit: 09/27/07 at 14:49:14 by frankuitaalst »  

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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #7 - 09/27/07 at 23:06:44
 
In the following sim it is clear how Jupiter whipes out the nearby asteroids .  
360 asteroids are initially orbiting at Jupiters orbit +/- 2% .  
The simulation covers a little bit more than 12 years corresponding plusminus to one Jovian year .  
Jupiter is shown as the pink dot at 5 'o clock in this rotating frame.  
It's amazing how quickly Jupiter clears the gap .
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Jup3602pcRot.gif
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Re: Jupiter, Earth's savior?
Reply #8 - 09/28/07 at 08:07:11
 
Just out of curiosity, does anything change if you remove Saturn from the system? I know that there are resonances with Saturn (nu1, I think) that serve to define inclination/eccentricity limits in the main belt, but I don't know if those apply in the situation you've set up here.
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #9 - 09/28/07 at 09:35:02
 
Heres the same system , but run for 170 years . A screenshot corresponds with 1 year .  
It's remarkable how Jupiter pulls the asteroids from the outside and drives them away to the inside .  
There also seem ,on average , to be more asteroids leading Jupiter then there are trailing .  
The system seems to behave somewhat chaotically but NO asteroid was lost in this period although they all have a diameter of 10 km .
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Jup360AstRotCtd.gif
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #10 - 09/30/07 at 06:55:48
 
I don't think Saturn plays a big role in this sim , but I'll give it a trail .  
Wondering if asteroids may behave differently dependent upon their initial orbit I created three orbits : yellow = AU Jup ; green = AUJup-3% and blue = AUJup+3% .  
Total of bodies is 360.  
The sim herunder uses three screenshots per year and covers 40 years of simulation .  
It's nice to see how the different families of asteroids "round the corner" in a different way . There's also a difference in the leading and trailing part of the ring .
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3120JupRot.gif
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Re: Jupiter, Earth's savior?
Reply #11 - 09/30/07 at 13:17:56
 
How far does Jupiters influence on asteroids extends ?  
Its influence is amazing as can be seen in the following pictures ..
240 low mass asteroids were positionned  at 4AU ( 600 mio  km ) ie more than 1AU from Jupiter .  
Jupiter is situated at the bottom of the frame ( not always visible ) .  
Its hard to believe how Jupiter modifies the initial circular orbits of the asteroids ...
(positionning the asteroids at 650 mio km gives even more dramatic pictures )  Huh.  
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600JupRot1.gif
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Re: Jupiter, Earth's savior?
Reply #12 - 10/01/07 at 13:02:05
 
Frankuitaalst. If you look at the numbers its not that difficult to imagine why.
Jupiter is approx 1E-3 (9.5E-4 really) solar masses and in your sim its 4 times closer 1au vs 4 au. So considering the point when they are perfectly aligned, jupiter asteroid sun. The force in the jupiter direction is a significant % of the solar direction. (Fj/Fs)=1E-3/(1/16) or 1.6E-2 which is 1.6%.
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frankuitaalst
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Re: Jupiter, Earth's savior?
Reply #13 - 10/01/07 at 22:30:47
 
your calculation is right .  The 1.6% may seem small , and in fact it is , but this gives the asteroid a direction to Jupiter . The net force grows as distance decreases , so that this crazy figures may arise .
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Re: Jupiter, Earth's savior?
Reply #14 - 10/02/07 at 10:06:43
 
The influence of Jupiter also works of course when the asteroids orbit at the outside .  
Hereunder a simulation running for 100 years .  
The asteroids are in a 3:2 resonance to Jupiter  (AU : 6.817 to 5.203 Jup).  
The influence of Jupiter is small in the beginning but due to the resonance some knots are build after several years.  
After more years it seems that 3 knots are build .
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