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Asteroids (Read 146978 times)
frankuitaalst
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Re: Asteroids
Reply #60 - 09/24/07 at 09:20:22
 
One of the most "tortured" asteroids is surely asteroid 2002GJ8.  
This one has a very eccentric orbit and  comes very close to Jupiter . This results in a drastic change of  its orbit as can be seen in the following picture .
The sim spans 150 years . The three first frames are back in time (50 years ) . The rest is straight forward .
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2002GJ8.gif
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frankuitaalst
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Re: Asteroids
Reply #61 - 09/30/07 at 04:58:51
 
Asteroid 2007SJ : the threat seems to be gone .  Smiley
After some more days ob observation the error on the measurements seems to be reduced , giving the asteroid a minimum diestance to earth of about 0.04 AU . Period remains the same as before .  
Heres the orbit in a rotating frame : the new orbit appears very close to the last one . The orbit estimated on 23/09 is still indicated as the dark green orbit .
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2007sj3009.gif
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frankuitaalst
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Re: Asteroids
Reply #62 - 10/05/07 at 12:33:29
 
A "lost" asteroid was found again recently .  
The asteroid 6344-PL was discovered in 1960 and was lost for several years .  
Recently another asteroid was discovered : 2007RR9 . I stored its data on 12/09/07.
 
According to an article in the BAD-forum the asteroid 2007RR9 is now considered as the lost asteroid 6344-PL . This matching was done recently . Good job .  Smiley
As I stored the data of 2007RR9 on 12/09/2007 and yet have the data of 6334-PL it's easy to compare the orbits . The light green orbit represents the orbit of 6344PL . The dark one the otbit of 2007RR9.  
I notced that JPL has deleted the previous data of 2007RR9.  
In the figure I marked the situation on 12/09/07 .
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2007RR.gif
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frankuitaalst
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Re: Asteroids
Reply #63 - 10/15/07 at 07:09:34
 
Another Asteroid is on its way to Earth ...
2007SJ doesn't seem to be a threat anymore but its brother 2007TU24 , recently discovered ,takes over .  
According to Neodys the asteroid will make a close pass to Earth on 29/01/2008 within 0.0037 AU , maybe as close as 0.00186 AU .  
Hereunder is a picture : shown is the Earth at center with the orbit of the moon .  
Light green is the path of the asteroid as known now .  
Dark green is the path as it was known yesterday .  
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2007TU24_15102007.jpg
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Re: Asteroids
Reply #64 - 10/15/07 at 09:36:36
 
Thanks for keeping us safe, Frank  Grin
 
I made a .gsim file for anyone who wants to play with this asteroid.  It misses Earth by less than 600,000 km.  It will be interesting to follow it as its orbit is refined.
 
http://www.orbitsimulator.com/gravity/simulations/2007TU24.gsim
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frankuitaalst
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Re: Asteroids
Reply #65 - 10/15/07 at 12:08:54
 
I'll do all of my best Tony  Grin . We have to watch this one as the threat according to Palermo is even bigger than that of Apophis ! It's not small either : more than 200 m in diameter . Also the encounter is only 3 months from now ...  
BTW : I'm very interested in simulating negative masses but it seems GravSim doesn't allow this .  
Any idea why ?
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Re: Asteroids
Reply #66 - 10/15/07 at 14:15:24
 
It should allow it.  I never put a negative filter in the code.  I just tried setting the Sun's mass to its negative value.  The planets all scrammed.
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frankuitaalst
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Re: Asteroids
Reply #67 - 10/15/07 at 14:25:15
 
Well I guessed it should work also . Thats funny ... I tried to set one planet to negative and it just behaved as normal .  undecided
Reason I want to do this is the following : suppose you have a bunch of masses ( a cloud ) . One part of the cloud is positve , the other negative . I guess we would obtain 2 distinct systems : one positive , one negative . Correct ?  Or maybe all is ejected . I'm anxious to try it .  
You're right : setting the Sun to negative mass throws the planets out . Thats fine .  
However changing an individual mass to negative doesn't have an effect .  undecided
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Re: Asteroids
Reply #68 - 10/15/07 at 21:42:35
 
Quote from frankuitaalst on 10/15/07 at 14:25:15:

However changing an individual mass to negative doesn't have an effect .  undecided

The Sun pulls hard, the planet pushes slightly.  The vectors add to a vector pointed to the Sun at least 99% as strong as if both the planet and Sun pulled.  That's the advantage of being a star.  You overwhelm everything else.
 
Try making an object orbit the anti-mass planet, and you will see that all is not well.
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frankuitaalst
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Re: Asteroids
Reply #69 - 10/16/07 at 07:56:09
 
There are days one can feel himself really stupid  Sad. yesterday was such a day . Of course ...
Take : m.a= GM.m/rČ , give the body a negative mass => a= GM/rČ , doesn't matter .  
Give the sun a negative mass : => a= -GM/rČ , result :body is repelled .  
 
In the meantime 2007TU24 has another observation. It comes closer than yesterday .  
In annex the view from aside . In the view from above the change towards earth is much bigger .
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fsscr018.jpg
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Re: Asteroids
Reply #70 - 10/19/07 at 09:55:39
 
The asteroid 2007TU24 is now demoted in threat , leaving the honours to Apophis again , as new observations are available .  
Herunder the path of the asteroid close to Erath at end of januari 2008. It will not come closer than 0.0375AU . The parallel path shown are previous observations .
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2007TU24dual.gif
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Re: Asteroids
Reply #71 - 10/28/07 at 00:49:48
 
Recently discovered : the 2007UT3 asteroid .  
It has a near 2:3 resonance to earth as can be seen herunder . Moreover it also is a near Venus and Mercury asteroid .
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2007ut3.gif
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Re: Asteroids
Reply #72 - 10/28/07 at 04:39:32
 
According to the latest estimations 2007TU24 will come as close as 1.4 Moon Distance to Earth on Jan 29th 2008.  Due to the close encounter the asteroids parameters are changed considerably as the next figure shows .  
The asteroid gets into a wider orbit , is gaining eccentricity and comes closer to the eccliptic plane as a result of Earhs influence .  
Things may change a little as new observations become available after he full moon .
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2004TU24SMA.jpg
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Re: Asteroids
Reply #73 - 10/28/07 at 05:28:25
 
The serious threat from 2007SJ seems definitively gone since the last observations on 25/10/07.  
The animation herunder gives the path of the large asteroids last three observations ( for 25/10, 12/10 and 30/09 ) . Light green is the last observations prediction .  
The animation shows the path from above and from aside , in both cases in rotatiig frame to Earth .  
 
From the NeoDys Site the data for closest approach to Earth.  
   EARTH  1954/01/02.71495  
   EARTH  1974/02/02.52411  
   EARTH  1994/01/22.55848  
   EARTH  2014/01/21.87239  
   EARTH  2034/02/25.72364

Remarkable is the period of almost exactly 20 years between 2 close approaches .  
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« Last Edit: 10/28/07 at 07:56:34 by frankuitaalst »  

2007SJ2510.gif
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frankuitaalst
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Re: Asteroids
Reply #74 - 11/01/07 at 07:32:31
 
This asteroid should be in the Kozai posts ...
Asteroid 2001AU43 is the one with the highest known inclination of all Near Earth asteroids .  
It is as highly as 72° degrees inclined to the ecliptic plane , making it an example for the Kozai mechanism.  
The picture hereunder is the result of a simulation for 450 years , showing the evolution of eccentricity and inclination .  
The asteroid still gains inclination .
According to Kozai the function cosi*sqrt(1-e^2) should be constant . The lower picture gives the evolution of this value ( shows to be more or less constant ) .  
I was able to find a recent picture of this asteroid taken by the Hubble Space Telescope  , which is pasted in the background Shocked.
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Ast2001AU43.jpg
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