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Earth Could Collide With Other Planets
Everybody put on your helmet;
Smivs writes "Astronomers calculate there is a tiny chance that Mars or Venus could collide with Earth — though it would not happen for at least a billion years.
The finding comes from simulations to show how orbits of planets might evolve billions of years into the future. But the calculated chances of such events occurring are tiny. Writing in the journal Nature, a team led by Jacques Laskar shows there is also a chance Mercury could strike Venus and merge into a larger planet. Professor Laskar of the Paris Observatory and his colleagues also report that Mars might experience a close encounter with Jupiter — whose massive gravity could hurl the Red Planet out of our Solar System."
mors certa, hora incerta
Wherever you go... There you are. B.B.
There are tiny odds of just about anything happening, why is it news?
We've known for almost a hundred years (since Poincare more or less) that the 3 body problem is inherently chaotic and not terribly stable and here we have an n body problem for large n. All they seem to have done here is list some of the more catastrophic possible outcomes if the system becomes seriously unstable.
first they announce that the recession is over in the UK (yeh right!)
then we find out earth is about to collide with another planet
at least the later is more believable :D
Next up.. How to make a tinfoil hat that can stop the CIA's mind control rays.
You have my undivided attention.
Posts not to be taken literally. Almost everything is sarcasm.
Let's go back to crystalline spheres and immutable heavens. That was a much safer design model
You see? You see? Your stupid minds! Stupid! Stupid!
They're killing independent George!
And no need to switch to 128bit timestamp when the Earth is no more. What a relief.
Give a geek a model, and he'll fret for a day. Teach a geek to model, and he'll have major news media fretting forever...
There, fixed that for you. Because:
Give a man a model, and he'll have a great time with her.
This is not the sig you're looking for.
Ok, here's a question: Has this happened in the past?
It doesn't take long playing with simple, fun orbit simulators to see that while most planetesimals get glommed, a few get chucked. Escape velocity from the Sun at Mars distance is WAY MORE* (technological term) than Jupiter could perturb. Some things tossed could have 'very long' periods, but still not escape. THAT would be news.
And yes, I am a rocket scientist and yes, I HAVE done the math.
Vcircular * sqrt(2) = Vescape! 41% is too much, even for Jupiter.
With the movie remake of When Worlds Collide due out in 2010, a story like this would be one way to create a buzz.
http://www.imdb.com/title/tt0455856/
ceci n'est pas un sig
How do you know this is the fault of the scientists? It could very easily be lazy and/or sensationalistic journalism -- same stuff as "this has as much info as x libraries of congress" or "as much volume as x ping-pong balls", or half of what kdawson posts.
Hail Eris, full of mischief...
E pluribus sanguinem
Think of it in terms of two cars colliding head-on, literally on a planetary scale: the planetary crust that seems like solid rock to you on the human scale is more like the crumple zone of a car's frame. When the planets collide, they would buckle and fuse together. In the example of 2 cars colliding, there would likely be some rebound and the cars would come to rest a few feet apart (the cars' respective centres of gravity are insignificant compared to the forces of friction on the pavement). On the planetary scale, what's left of the planets' respective centres of gravity would continue to pull & keep them together (with a relatively small percentage of debris lost, most of that would then be recaptured into orbit for the immediate future).
When all of your wishes have been granted, many of your dreams will be destroyed - Marilyn Manson
that the earth may simply stop existing because if it's quantum state. This applies to the universe as well.
This is why this isn't news.
There was a student dozing off in a class in college and the professor makes the remark that the Sun will one day go out, but this will probably not happen for at least a billion years.
The student wakes up suddenly with a panicked look and asks the professor to repeat his statement.
The professor does so, and the student says "Whew. I thought you said a million years."
I can't seem to bring myself to worry, either way.
I put on my robe and wizard hat..
Even if they can somehow account for every small asteroid that will change the course of Earth's orbit over a billion years, they can't possibly account for the possibility (near-certainty unless we nuke ourselves to death) that we will, possibly before the end of this century, be able to cause drastic changes to anything in the solar system.
The current theory is that a Mars-sized planet collided with Earth sometime in history. When this planet, usually named Theia, collided with Earth, some of the disturbed matter from both planets got ejected into space, some fell onto and became part of Earth, and some got caught in orbit around Earth as natural satellites.
The resulting dust either escaped or eventually coalesced into the modern Earth and Moon.
"Screw Sun, cross-platform will never work. Let's move on and steal the Java language." - Visual J++ Product Manager
Why can't they come up with a plausible theory of apocalypse by snu-snu?
Unfortunately, it seems, the world ends not with a bang but a whimper.
A Jupiter like planet has been catapulted out of another solar system and is planning a visit... Latest calculations predict collision with Earth somewhere at the end of 2012.
"The year, 1994. From out of space, comes a runaway planet, hurtling between the Earth and the Moon, unleashing cosmic destruction. Man's civilization is cast in ruin.
"Two thousand years later, Earth is reborn. A strange new world rises from the old. A world of savagery, super-science, and sorcery.
"But one man bursts his bonds to fight for justice. With his companions, Ookla the Mok and Princess Ariel, he pits his strength, his courage, and his fabulous Sunsword, against the forces of evil. He is Thundarr, the Barbarian!"
Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
This prediction is as meaningless as the one of Mercury falling into the sun in a billion years for the same reasons.
The inner solar system is chaotic with a Lyuapanov time on the order of 5 million years - On average, two very nearby orbits will change their distance between each other in phase-space by a constant in that time. This makes the solar system's future evolution profoundly dependent on initial conditions and integrator accuracy.
First of all it's hard to maintain integration accuracy for more than a few Lyuapanov times, especially when the system has such an enormous dynamic range in mass and characteristic orbital times as the solar system, since this requires that the integrator be exponentially more accurate. The outer solar system is routinely integrated for hundreds of millions of years (and I've run several such simulations myself with a 10th order symplectic integrator) but most simulations of the inner solar system run for a few tens of millions of years at most. A 5 billion year integration of the inner solar system will require that errors be supressed on the order of e^-1000, which is absurd.
Second of all, chaotic systems are also defined by their extreme dependence on initial conditions. Our observational knowledge of the positions of the planets only extends to about 7 digits at best, which makes any simulation in which displacing something by 1 part in e^1000 changes the outcome meaningless. In addition, at such levels of precision other effects come into play - Relativity changes the details of Earth's orbit significantly from the classical prediction after about 10 million years.
You can plug whatever numbers you want into a symplectic integrator and it'll run as long as you want without blowing up, but that doesn't mean the numbers mean anything.