Mike Brown's Planets: The long road to a Titan storm
Titan, Iapetus, and the Great Crash
Monday, August 17, 2009
Sunday, August 16, 2009
Titan, Iapetus, and the Great Crash
From Titan, you can't see the rings of Saturn very well. It's hard to see through the smoggy atmosphere and besides, Titan orbits in the plane of Saturn's rings, so all you see is the edge. If you try it from Titan's poles to get a better perspective, Saturn and it's rings are on the horizon and you are looking through more smog.
From airless Iapetus, however, you can get a great perspective from above the rings, or below. You can see the other moons, too. There's a nice artist's depiction on Wikipedia:
http://en.wikipedia.org/wiki/File:Saturn_from_Iapetus.jpg
Iapetus' orbital inclination to Saturn's equator:
http://en.wikipedia.org/wiki/Iapetus_(moon)
is 15.47 degrees. It's inclination to the ecliptic is 17.28 degrees, but to the Laplace plane it's inclination is 7.52 degrees. If it formed in the plane of Saturn's rings, it's made a long, strange trip indeed.
"Current triaxial measurements of Iapetus give it dimensions of 747.1 × 749 × 712.6 km, with a mean radius of 736 ±2 km.[2] However, these measurements may be inaccurate on the kilometer scale as Iapetus's entire surface has not yet been imaged in high enough resolution. The observed oblateness corresponds to a rotation period of 10 hours, not to the 79 days observed." That 10 hour period is shorter than inner moon Mimas' 22.6 hours, so it's a pretty sure bet that it didn't pick up that kind of rotation from Saturn.
Iapetus' semimajor axis of 3,560,000 km is far outside of Titan's 1,220,000 km. It's like a captured body. Yet, it's about the size of Saturn's other largest moons, except giant 5150 km diameter Titan. It's 1470 km diameter fits right in between Dione's 1120 km and Rhea's 1528 km. It's an inner moon - and yet it's an outer moon.
Titan has it's own anomalies. It's as big as a planet, almost the size of Jupiter's largest moons, yet the Saturn system has only one third the mass of the Jupiter system. It's like an intruder into the orderly mass distribution of a normal gas giant. It has an atmosphere, too.
That atmosphere has two inert gases, helium and argon, both decay products of radioactive materials. If Titan can hang on to even a little bit of helium, it should hang on to neon, but there is none. In fact, there's only one argon isotope, argon-40, and no krypton or xenon. It appears as though Titan lost it's original atmosphere. It must have collided with something big.
I propose it collided with itself.
Half the object formed in the Sun/Saturn Lagrange point L4 and the other half formed in the L-5 point. Having run plenty of objects on GravitySimulator, I can attest that objects orbiting one of these points but far from it spend a long time hanging around the L-3 point. With Jupiter stirring things up, a capture as a binary is possible (Jupiter makes it a non-Lagrange three body problem). Now we have a binary object in orbit around the Sun at the same distance as Saturn. It's too big to fit into a Lagrange point, so eventually it will approach Saturn.
When a small binary approaches a large object, there can be several results. One could be captured and the other thrown away at a considerable velocity. That occurs if, at closest approach, the three bodies are all in a straight line. However, I don't think that happened at Titan. If both objects are at the same altitude at closest approach, then their revolution with respect to each other is cancelled by the larger objects gravity and they attract each other and collide. I've said elsewhere that I think that's what happened to Triton and Haumea when they passed Neptune. That was a glancing blow that imparted impressive spin to Haumea.
But the Titan halves apparently made a head-on collision. This would release significantly more energy than if the halves were made of high explosives. It would turn into a blob of gas, highly vulnerable to tidal forces.
In spite of the explosion, Titan would fly on past Saturn unless something carried away some of it's angular momentum. If something comes down, something else must go up. I would nominate unfortunate Iapetus for this role. Iapetus would have whatever spin it would have from being tidally locked with Titan at it's closest approach.
A ten hour orbit around Titan would correspond to a distance of 6680 km, but Iapetus was likely moving at escape velocity so you would multiply that by the square root of two to get 9400 km, just outside Titan's Roche limit. So Iapetus did not explode but went sailing off into orbit around the Sun.
Meanwhile, the blob of gas that was Titan begins raining iron. Since we have a large object kicking a small object out of the system, Titan would have a highly eccentric orbit from being just barely captured. Being large it would be subjected to tidal forces which would let it easily get into the plane of Saturn's rotation. As it's eccentric orbit decayed, it's mass would spill out of it's Hill sphere and form a torus outside of it's eventual circular orbit.
Millions of years later, Iapetus returns, having been tossed around a little by the other gas giants. It plows into the torus of ground-up Titan remains and is aerobraked into a new orbit around Saturn. Iapetus gathers a ring from the torus and it decays into the Voyager mountains. Iapetus clears it's orbit and takes it's rightful place as a major moon.
That's my ideas on the history of Titan and Iapetus. Anybody's welcome to comment if you care to.
Thanks :)
Michael C. Emmert
From airless Iapetus, however, you can get a great perspective from above the rings, or below. You can see the other moons, too. There's a nice artist's depiction on Wikipedia:
http://en.wikipedia.org/wiki/File:Saturn_from_Iapetus.jpg
Iapetus' orbital inclination to Saturn's equator:
http://en.wikipedia.org/wiki/Iapetus_(moon)
is 15.47 degrees. It's inclination to the ecliptic is 17.28 degrees, but to the Laplace plane it's inclination is 7.52 degrees. If it formed in the plane of Saturn's rings, it's made a long, strange trip indeed.
"Current triaxial measurements of Iapetus give it dimensions of 747.1 × 749 × 712.6 km, with a mean radius of 736 ±2 km.[2] However, these measurements may be inaccurate on the kilometer scale as Iapetus's entire surface has not yet been imaged in high enough resolution. The observed oblateness corresponds to a rotation period of 10 hours, not to the 79 days observed." That 10 hour period is shorter than inner moon Mimas' 22.6 hours, so it's a pretty sure bet that it didn't pick up that kind of rotation from Saturn.
Iapetus' semimajor axis of 3,560,000 km is far outside of Titan's 1,220,000 km. It's like a captured body. Yet, it's about the size of Saturn's other largest moons, except giant 5150 km diameter Titan. It's 1470 km diameter fits right in between Dione's 1120 km and Rhea's 1528 km. It's an inner moon - and yet it's an outer moon.
Titan has it's own anomalies. It's as big as a planet, almost the size of Jupiter's largest moons, yet the Saturn system has only one third the mass of the Jupiter system. It's like an intruder into the orderly mass distribution of a normal gas giant. It has an atmosphere, too.
That atmosphere has two inert gases, helium and argon, both decay products of radioactive materials. If Titan can hang on to even a little bit of helium, it should hang on to neon, but there is none. In fact, there's only one argon isotope, argon-40, and no krypton or xenon. It appears as though Titan lost it's original atmosphere. It must have collided with something big.
I propose it collided with itself.
Half the object formed in the Sun/Saturn Lagrange point L4 and the other half formed in the L-5 point. Having run plenty of objects on GravitySimulator, I can attest that objects orbiting one of these points but far from it spend a long time hanging around the L-3 point. With Jupiter stirring things up, a capture as a binary is possible (Jupiter makes it a non-Lagrange three body problem). Now we have a binary object in orbit around the Sun at the same distance as Saturn. It's too big to fit into a Lagrange point, so eventually it will approach Saturn.
When a small binary approaches a large object, there can be several results. One could be captured and the other thrown away at a considerable velocity. That occurs if, at closest approach, the three bodies are all in a straight line. However, I don't think that happened at Titan. If both objects are at the same altitude at closest approach, then their revolution with respect to each other is cancelled by the larger objects gravity and they attract each other and collide. I've said elsewhere that I think that's what happened to Triton and Haumea when they passed Neptune. That was a glancing blow that imparted impressive spin to Haumea.
But the Titan halves apparently made a head-on collision. This would release significantly more energy than if the halves were made of high explosives. It would turn into a blob of gas, highly vulnerable to tidal forces.
In spite of the explosion, Titan would fly on past Saturn unless something carried away some of it's angular momentum. If something comes down, something else must go up. I would nominate unfortunate Iapetus for this role. Iapetus would have whatever spin it would have from being tidally locked with Titan at it's closest approach.
A ten hour orbit around Titan would correspond to a distance of 6680 km, but Iapetus was likely moving at escape velocity so you would multiply that by the square root of two to get 9400 km, just outside Titan's Roche limit. So Iapetus did not explode but went sailing off into orbit around the Sun.
Meanwhile, the blob of gas that was Titan begins raining iron. Since we have a large object kicking a small object out of the system, Titan would have a highly eccentric orbit from being just barely captured. Being large it would be subjected to tidal forces which would let it easily get into the plane of Saturn's rotation. As it's eccentric orbit decayed, it's mass would spill out of it's Hill sphere and form a torus outside of it's eventual circular orbit.
Millions of years later, Iapetus returns, having been tossed around a little by the other gas giants. It plows into the torus of ground-up Titan remains and is aerobraked into a new orbit around Saturn. Iapetus gathers a ring from the torus and it decays into the Voyager mountains. Iapetus clears it's orbit and takes it's rightful place as a major moon.
That's my ideas on the history of Titan and Iapetus. Anybody's welcome to comment if you care to.
Thanks :)
Michael C. Emmert
Sunday, April 19, 2009
Bigger Systems Are More Stable
Howdy folks :)
Well, I am finally able to answer Vagueofgodalming's question. He's right, if there is more spacing between planets the system is much more stable.
It took a while to get a baseline simulation that worked. I thought it would be simple, double the distances and divide the velocities by the square root of two. Trouble is, I did that for the Sun, too, which caused an immediate crash.
When I ran the simulation for the larger system with the largest mass on the outside (Neptune) it lasted 2.86 million years. Unfortunately, it crashed as I was preparing my diabetes medicine, which involves a syringe, so there's a couple of hundred thousand years over which it could have crashed. That's quite a bit longer than the closer simulation.
When I made the inside (Jupiter) mass the largest (8 Jmasses) it ran quite stably for over 11 million years, when I decided to cut it off. What this tells me is that as expected, the larger mass being on the inside makes it more stable.
When I did a simulation with all masses at 3.75 J's it fell apart really fast, like in 86000 years. So I ran it over and it fell apart in 1.88 million years. Jupiter was ejected, Saturn had a highly eccentric orbit from a little over Jupiter's (doubled) distance down to about the altitude of our real system's Mars. Earth survived.
I can't get the clock stopped for when I start these simulations, so the initial conditions are always very different. So, watching these systems decay is like watching for a radium atom to decay. There's an average life, but it could go off at any time.
If you could do thousands and thousands of simulations, then you would get an average lifetime of these systems, just like you can get an average half-life of exploding atoms. But simulations take a long time. That's impractical. So, I'm doing snapshots.
It seems that these systems are least stable when all the planets are the same mass. That might not be what natural systems are like, in fact I would imagine that usually the largest planet is on the inside. But it occured to me that an artificial system with the masses all the same is the best for getting a clear vision of what is happening with these gravitational interactions. That way you don't have to imagine the effect of the masses.
Watching these things evolve I have noticed that the strongest perturbations occur when the inner planet is at aphelion, excuse me, apastron, and the outer planet is at periastron at the same time and the same place. Thus they are closest together. The most stable configuration is when all the planets have circular orbits. The systems hum along quite nicely when that happens.
But, eventually one of the orbits will get eccentric. Then it will start precessing. At that point it starts to affect the other planets and they get eccentric and start precessing, too. Pretty soon, the periastron of the outer object is lined up with the apastron of the inner object, so there is some definite point at which they are closest together.
At this point "resonances" kick in. We've all heard of the famous resonances like Pluto's, where Pluto make two orbits for every three Neptune makes (talking about the "real" planets here). Of course there are all kinds of resonances in between the 3:2's or 5:2's or whatever. But when the resonances start pumping energy between the objects, this changes the orbital periods. So usually the resonance goes away.
When you do these simulations, ideas occur to you about how to observe them or streamline them or manipulate them. I looked at these things and the orbits seemed to swell and shrink. I hit on an observing technique tonight. You can turn the trails that the objects leave behind them on or off. You can also turn off the plotting function so that the machine does not have to create 30 displays per second and so runs faster. I hit on a sequence; turn the trails off and then the objects are displayed as dots. Then turn the plotting function off and the last positions are frozen in place. Then turn the trails back on while it's still in "don't plot" mode; when you resume the plot mode, the dot is still there and so you can see whether the orbit has shrunk overall or expanded, whether it has gained or lost energy.
There is a certain amount of total energy in this sytem and that is a conserved quantity. A very early result I noticed is that the orbit of Jupiter (the "fake" one with 3.75 Jupiter masses) shrank just a little and the other three objects moved out quite a bit. That makes sense; the inner object moves the fastest and so has the most energy.
But a little while later, all the orbits shrank. I still havent' figured that one out, but I did notice (due to panicky searching) that in this case, all the orbits were quite circular. I think there must be some mathematical formula there, but I don't know what it is.
Addressing the results of these simulations to the Main Question, I'm going to keep the #13 square in the betting pool for how many "terroids" Kepler will find. But I have moved to thinking now that that is probably pessimistic, rather than optimistic, i.e. my estimate of the number of terroids has gone up.
Hooray!
:)
-Michael C. Emmert
Well, I am finally able to answer Vagueofgodalming's question. He's right, if there is more spacing between planets the system is much more stable.
It took a while to get a baseline simulation that worked. I thought it would be simple, double the distances and divide the velocities by the square root of two. Trouble is, I did that for the Sun, too, which caused an immediate crash.
When I ran the simulation for the larger system with the largest mass on the outside (Neptune) it lasted 2.86 million years. Unfortunately, it crashed as I was preparing my diabetes medicine, which involves a syringe, so there's a couple of hundred thousand years over which it could have crashed. That's quite a bit longer than the closer simulation.
When I made the inside (Jupiter) mass the largest (8 Jmasses) it ran quite stably for over 11 million years, when I decided to cut it off. What this tells me is that as expected, the larger mass being on the inside makes it more stable.
When I did a simulation with all masses at 3.75 J's it fell apart really fast, like in 86000 years. So I ran it over and it fell apart in 1.88 million years. Jupiter was ejected, Saturn had a highly eccentric orbit from a little over Jupiter's (doubled) distance down to about the altitude of our real system's Mars. Earth survived.
I can't get the clock stopped for when I start these simulations, so the initial conditions are always very different. So, watching these systems decay is like watching for a radium atom to decay. There's an average life, but it could go off at any time.
If you could do thousands and thousands of simulations, then you would get an average lifetime of these systems, just like you can get an average half-life of exploding atoms. But simulations take a long time. That's impractical. So, I'm doing snapshots.
It seems that these systems are least stable when all the planets are the same mass. That might not be what natural systems are like, in fact I would imagine that usually the largest planet is on the inside. But it occured to me that an artificial system with the masses all the same is the best for getting a clear vision of what is happening with these gravitational interactions. That way you don't have to imagine the effect of the masses.
Watching these things evolve I have noticed that the strongest perturbations occur when the inner planet is at aphelion, excuse me, apastron, and the outer planet is at periastron at the same time and the same place. Thus they are closest together. The most stable configuration is when all the planets have circular orbits. The systems hum along quite nicely when that happens.
But, eventually one of the orbits will get eccentric. Then it will start precessing. At that point it starts to affect the other planets and they get eccentric and start precessing, too. Pretty soon, the periastron of the outer object is lined up with the apastron of the inner object, so there is some definite point at which they are closest together.
At this point "resonances" kick in. We've all heard of the famous resonances like Pluto's, where Pluto make two orbits for every three Neptune makes (talking about the "real" planets here). Of course there are all kinds of resonances in between the 3:2's or 5:2's or whatever. But when the resonances start pumping energy between the objects, this changes the orbital periods. So usually the resonance goes away.
When you do these simulations, ideas occur to you about how to observe them or streamline them or manipulate them. I looked at these things and the orbits seemed to swell and shrink. I hit on an observing technique tonight. You can turn the trails that the objects leave behind them on or off. You can also turn off the plotting function so that the machine does not have to create 30 displays per second and so runs faster. I hit on a sequence; turn the trails off and then the objects are displayed as dots. Then turn the plotting function off and the last positions are frozen in place. Then turn the trails back on while it's still in "don't plot" mode; when you resume the plot mode, the dot is still there and so you can see whether the orbit has shrunk overall or expanded, whether it has gained or lost energy.
There is a certain amount of total energy in this sytem and that is a conserved quantity. A very early result I noticed is that the orbit of Jupiter (the "fake" one with 3.75 Jupiter masses) shrank just a little and the other three objects moved out quite a bit. That makes sense; the inner object moves the fastest and so has the most energy.
But a little while later, all the orbits shrank. I still havent' figured that one out, but I did notice (due to panicky searching) that in this case, all the orbits were quite circular. I think there must be some mathematical formula there, but I don't know what it is.
Addressing the results of these simulations to the Main Question, I'm going to keep the #13 square in the betting pool for how many "terroids" Kepler will find. But I have moved to thinking now that that is probably pessimistic, rather than optimistic, i.e. my estimate of the number of terroids has gone up.
Hooray!
:)
-Michael C. Emmert
Friday, April 17, 2009
Looks Like Critical Mass is about 15 J's
I got my first three baseline simulations done. I used the same distances as found in our Solar system. First, Jupiter was made 1 Jupiter mass, Saturn 2Js, Uranus 4Js and Neptune 8 Js. Now it took a reasonable length of time to collapse. By fortunate good luck, that was about 62,000 years. I let it run longer just to watch it, but by 62 ky there were serious distortions like orbits crossing each other and extreme eccentricity. Saturn wound up the inner planet about half way into the asteroid belt with an aphelion a little under Jupiter's original orbit. Neptune kicked up surprisingly high.
Next, the mass ordering was reversed, Jupiter 8 Js, Saturn 4Js, Uranus 2Js and Neptune 1J. I thought it might be stabler. That lasted 91 ky before it looked totally weird. This time, due to the perburbations of the type modeled by Kevin at Chiron, it looked like Uranus was going to wind up a roaster. It had gotten in quite close to the Sun. Earth's orbit was cranked about 60 or 70 degrees to the invarient plane, perihelion about 50 Gm and aphelion about 250 Gm.
Then I assigned each planet 3.75 Jupiter masses and it lasted 82 ky. Jupiter and Saturn's orbits seemed to touch when viewed from the poles and the other two were out there a little beyond the Kuiper Belt.
Kevin had put a standard disclaimer that said his simulation was only good for about 100,000 years. That's pretty close to consensus for how far you can trust simulations and Kevin's right, but I don't know if he is talking about trying to find Chiron in a telescope after that time, in which case his timeframe surely works, or if he is just wanting a representative case to show how orbits can become very eccentric and shrink drastically. If you're trying to do the demonstration then at least 10 and maybe a hundred times that would probably do.
One source of error is that I can't get to the pause button fast enough for several years to go by and for Jupiter to achieve a full orbit. That clock starts fast! I guess I need to have a simulation paused at, say, April 1, 2012 and make sure they all start from there. I guess such a massive error might throw the length these things last off by several thousand years.
It was mere good fortune that I chose mass values that seemed to be critical for the distances found in our solar system. Now I am in a position to try to answer Vagueofgodalming's query about distances. But I don't know how long I should run it before I declare it "stable". I will try twice the distances. If that "looks" stable I will divide that by the square root of two, then the square root of two, etc.
In all these simulations with the different masses, I noticed that Uranus had the least stable orbit when the simulations first started, even though the distributions were different every time. The lines representing Uranus's orbit were up to about 5 mm apart on my monitor over a single orbit.
Tony Dunn's program has a "plot/don't plot" button and it's very good for following chaotic simulations. The idea here is that the machine calculates all the positions on the board and then creates a graphic display. It you hit "don't plot", then it stops making graphic displays every 30th of a second and as a result, the machine runs much faster. You can turn it on for 167 years and then turn it off and thousands of years will go by in a minute or so. Sometimes the planets enter stable circular phases and the plots are almost superimposed, while other planets show precession or large changes in orbital elements. It's real fun to watch ;)
:D
-Michael C. Emmert
Next, the mass ordering was reversed, Jupiter 8 Js, Saturn 4Js, Uranus 2Js and Neptune 1J. I thought it might be stabler. That lasted 91 ky before it looked totally weird. This time, due to the perburbations of the type modeled by Kevin at Chiron, it looked like Uranus was going to wind up a roaster. It had gotten in quite close to the Sun. Earth's orbit was cranked about 60 or 70 degrees to the invarient plane, perihelion about 50 Gm and aphelion about 250 Gm.
Then I assigned each planet 3.75 Jupiter masses and it lasted 82 ky. Jupiter and Saturn's orbits seemed to touch when viewed from the poles and the other two were out there a little beyond the Kuiper Belt.
Kevin had put a standard disclaimer that said his simulation was only good for about 100,000 years. That's pretty close to consensus for how far you can trust simulations and Kevin's right, but I don't know if he is talking about trying to find Chiron in a telescope after that time, in which case his timeframe surely works, or if he is just wanting a representative case to show how orbits can become very eccentric and shrink drastically. If you're trying to do the demonstration then at least 10 and maybe a hundred times that would probably do.
One source of error is that I can't get to the pause button fast enough for several years to go by and for Jupiter to achieve a full orbit. That clock starts fast! I guess I need to have a simulation paused at, say, April 1, 2012 and make sure they all start from there. I guess such a massive error might throw the length these things last off by several thousand years.
It was mere good fortune that I chose mass values that seemed to be critical for the distances found in our solar system. Now I am in a position to try to answer Vagueofgodalming's query about distances. But I don't know how long I should run it before I declare it "stable". I will try twice the distances. If that "looks" stable I will divide that by the square root of two, then the square root of two, etc.
In all these simulations with the different masses, I noticed that Uranus had the least stable orbit when the simulations first started, even though the distributions were different every time. The lines representing Uranus's orbit were up to about 5 mm apart on my monitor over a single orbit.
Tony Dunn's program has a "plot/don't plot" button and it's very good for following chaotic simulations. The idea here is that the machine calculates all the positions on the board and then creates a graphic display. It you hit "don't plot", then it stops making graphic displays every 30th of a second and as a result, the machine runs much faster. You can turn it on for 167 years and then turn it off and thousands of years will go by in a minute or so. Sometimes the planets enter stable circular phases and the plots are almost superimposed, while other planets show precession or large changes in orbital elements. It's real fun to watch ;)
:D
-Michael C. Emmert
Wednesday, April 15, 2009
"I Blew Up the Solar System" (repost from MySpace)
Tuesday, April 14, 2009
I Blew Up the Solar System...
It was science fiction, of course. Some science fiction authors have been so ambitious as to blow up the Universe. I just pulled out the standard simulation of our Solar system from the file in GravitySimulator and edited Jupiter, Saturn, Uranus, and Neptune to have 10 times the mass of Jupiter.It collapsed immediately. Saturn fell towards Jupiter, which promptly went into an eccentric orbit with it's high point at about the same altitude it had but a considerably lower low point, somewhere in the middle of the asteroid belt. Saturn was propelled in to a high, cigar shaped orbit well beyond Pluto, but it's low point was about the same altitude as Jupiter's high point. Both began precessing unsteadily, with the direction their cigars were pointed in shifting back and forth.Meanwhile, Uranus started heading for Neptune , then fell back towards Jupiter. Uranus, too, was flung out into the outer realm of ice and darkness. After a big wobble, Neptune settled unsteadily into a somewhat more elliptical orbit at about the same altitude.
Poor Pluto got massacred right away. In 3200 years, we lost Mars.
Inside that, though, it was surprisingly stable. Earth kept orbiting in a nice circle, just like the ancients believed it did..This whole project was triggered when Mike Brown wrote a blog about Immanuel Kant. Kant was a philosopher in a day when there was little difference between philosophy, science, and religion. He saw galaxies in his telescope and correctly guessed that they were organized by gravity. He wrote quite beautiful descriptions of this particular manifestation of the wonders of the Universe..Mike Brown had been invited to review a book by Alan Boss, "The Crowded Universe", about the development and launch of the Kepler mission to find Earthlike planets of other stars. "The Crowded Universe" describes some of the research so far concerning extrasolar planets.
We don't see the cute round circles the ancients saw in the orbits of the planets. They're chaotic; they throw each other around like professional wrestlers..I got some feedback on my post from Kevin Heidar and Vagueofgodalming. Kevin Heidar noted the large change in mass, so I shut down the spectacular science-fiction simulation and instead did one with the gas giant's masses at one Jupiter. Kevin noted that this is a very large change and he is right.Vagueofgodalming noted that increased distance between the planets would create more stability. That should be true, I'll have to try it.
I believe I will have to start with the most massive array of planets first. These simulations take a long time unless there is large instability. One that ends quickly like the 40 Jmass total sim tell you something quickly. The 4 total Jmass simulation has now gone 14 million years, that might be a long time by human standards but it's a blink in the eye of the life of a star. I can see by the widening of the tracks of the orbits caused by a slightly different orbit every time that the 4 Jmass simulation has not reached stability.
One significant result of the 40 Jmass total simulation was that one planet only dropped a little and threw two other planets the same size a considerable distance. What this might mean is that if the inner gas giant is the predominant mass, it will protect inner planets including prospective terroids from the chaos beyond them. What that means is that the Kepler mission will find a larger number of them.The next three and a half years are going to be very interesting!
http://blogs.myspace.com/index.cfm?fuseaction=blog.view&friendId=435573268&blogId=483317652
:)
Michael C. Emmert
I Blew Up the Solar System...
It was science fiction, of course. Some science fiction authors have been so ambitious as to blow up the Universe. I just pulled out the standard simulation of our Solar system from the file in GravitySimulator and edited Jupiter, Saturn, Uranus, and Neptune to have 10 times the mass of Jupiter.It collapsed immediately. Saturn fell towards Jupiter, which promptly went into an eccentric orbit with it's high point at about the same altitude it had but a considerably lower low point, somewhere in the middle of the asteroid belt. Saturn was propelled in to a high, cigar shaped orbit well beyond Pluto, but it's low point was about the same altitude as Jupiter's high point. Both began precessing unsteadily, with the direction their cigars were pointed in shifting back and forth.Meanwhile, Uranus started heading for Neptune , then fell back towards Jupiter. Uranus, too, was flung out into the outer realm of ice and darkness. After a big wobble, Neptune settled unsteadily into a somewhat more elliptical orbit at about the same altitude.
Poor Pluto got massacred right away. In 3200 years, we lost Mars.
Inside that, though, it was surprisingly stable. Earth kept orbiting in a nice circle, just like the ancients believed it did..This whole project was triggered when Mike Brown wrote a blog about Immanuel Kant. Kant was a philosopher in a day when there was little difference between philosophy, science, and religion. He saw galaxies in his telescope and correctly guessed that they were organized by gravity. He wrote quite beautiful descriptions of this particular manifestation of the wonders of the Universe..Mike Brown had been invited to review a book by Alan Boss, "The Crowded Universe", about the development and launch of the Kepler mission to find Earthlike planets of other stars. "The Crowded Universe" describes some of the research so far concerning extrasolar planets.
We don't see the cute round circles the ancients saw in the orbits of the planets. They're chaotic; they throw each other around like professional wrestlers..I got some feedback on my post from Kevin Heidar and Vagueofgodalming. Kevin Heidar noted the large change in mass, so I shut down the spectacular science-fiction simulation and instead did one with the gas giant's masses at one Jupiter. Kevin noted that this is a very large change and he is right.Vagueofgodalming noted that increased distance between the planets would create more stability. That should be true, I'll have to try it.
I believe I will have to start with the most massive array of planets first. These simulations take a long time unless there is large instability. One that ends quickly like the 40 Jmass total sim tell you something quickly. The 4 total Jmass simulation has now gone 14 million years, that might be a long time by human standards but it's a blink in the eye of the life of a star. I can see by the widening of the tracks of the orbits caused by a slightly different orbit every time that the 4 Jmass simulation has not reached stability.
One significant result of the 40 Jmass total simulation was that one planet only dropped a little and threw two other planets the same size a considerable distance. What this might mean is that if the inner gas giant is the predominant mass, it will protect inner planets including prospective terroids from the chaos beyond them. What that means is that the Kepler mission will find a larger number of them.The next three and a half years are going to be very interesting!
http://blogs.myspace.com/index.cfm?fuseaction=blog.view&friendId=435573268&blogId=483317652
:)
Michael C. Emmert
Simulations
Howdy, folks :)
I've decided to create this blog for anybody to post simulations of astronomical or other situations. The immediate situation is that at least two of us on Mike Brown's blog have gotten into discussion where the posters are actually taking time to do simulations. But, it's not "Kevin Heidar's Planets" or "Mike Emmert's Planets", it's "Mike Brown's Planets" and the discussion there is having the effect of hijacking a great blog. It's time I started my own blog, I've got one on MySpace but that's mostly for "people from my hometown" or "musicians".
I have tried to contact some of the other posters but doing that, I realized that with the setup of Blogspot there was no way for anybody to contact ME! OUCH! So, here it is, and a Crystal can be just about any little piece of knowlege, wisdom, humor, humanity, or whatever. As for why I call them "Crystals", it's to put the neat photo of me taken by Meaghan Niven to work :)
I have no more, and almost certainly less, technical proficiency than the average computer user so I guess I'll have to figure out how to work the buttons for such neat features as image posting and things like that. There are always links, of course.
Have fun here. Of course, personal attacks & such will be ruthlessly edited. Oh, well...
:)
-Michael C. Emmert
I've decided to create this blog for anybody to post simulations of astronomical or other situations. The immediate situation is that at least two of us on Mike Brown's blog have gotten into discussion where the posters are actually taking time to do simulations. But, it's not "Kevin Heidar's Planets" or "Mike Emmert's Planets", it's "Mike Brown's Planets" and the discussion there is having the effect of hijacking a great blog. It's time I started my own blog, I've got one on MySpace but that's mostly for "people from my hometown" or "musicians".
I have tried to contact some of the other posters but doing that, I realized that with the setup of Blogspot there was no way for anybody to contact ME! OUCH! So, here it is, and a Crystal can be just about any little piece of knowlege, wisdom, humor, humanity, or whatever. As for why I call them "Crystals", it's to put the neat photo of me taken by Meaghan Niven to work :)
I have no more, and almost certainly less, technical proficiency than the average computer user so I guess I'll have to figure out how to work the buttons for such neat features as image posting and things like that. There are always links, of course.
Have fun here. Of course, personal attacks & such will be ruthlessly edited. Oh, well...
:)
-Michael C. Emmert
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