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Changing Earth's Orbit Proposed
SEWilco writes "This BBC story points out that a team of astronomers have found a way to adjust the orbit of the Earth. They suggest moving a large asteroid past Earth and using its gravity to pull us out to a slightly different orbit. Their concern was how to keep the Earth cool as the Sun ages and warms up in a billion years. It's nice to see someone thinking of the long term."
...we'll tether 5 worlds togther and ride them to escape the Core Explosion...
Larry Niven used this idea In the novel "World out of time". Good Novel, done in the 70's I think.
Erlang Developer and podcaster
Thought I would mention a couple of things related to this subject.
1) Our sun is not big enough to go Super Nova, so don't worry about that. A Nova is a different thing that occurs in binary star systems so we don't have to worry about that either. What we do have to worry about is when the sun enters the Red Giant phase and begins to expand. That is what these scientists are pondering.
2) Any 3 body gravitational system is chaotic. A chaotic system does not mean that is is wild and out of control. It means that it is very difficult to predict because the system is very sensitive to initial conditions. However, this is often a benefit because a chaotic system can exhibit a large range of behavior, whereas a non chaotic system is stuck in it's stable behavior. Also because of the chaotic nature of a 3 body system very small perturbations can eventually greatly effect the system. This means that we would not need a very large asteroid to move the earth, a small one that approaches just right would do the trick, and it would happen over a very large time period (millions of years). However because of the chaotic nature of the system we cannot exactly predict exactly where the earth would end up (we could eliminate the possiblity of it plunging into the sun, or being ejected from the solar system). To pull this off we would probably need a series of asteroids to occasionally redirect the earth slightly (perhaps every few thousand years). Since the forces involved would be small the effects of tidal forces and effects on the environment would be small and gradual.
3) The earth already is moving away from the sun, because the sun is losing mass to the solar wind. My guess would be getting the mass loss of the sun correct would be the most difficult thing to work into the calculations since it isn't totally constant, and probably will become much more erratic as the sun begins to approach the red giant phase.
4) My guess is the thing people of the future would have to worry about isn't the sun expanding and heating the earth too much, but the sun will probably become much less stable as far as radiation output causing rapid heating (several degrees over a few hundred years) followed by rapid cooling. This kind of variability will probably wreck havoc on the environment. (This is all assuming we haven't already screwed things up ourselves).
5) This study is more relavent than you might think. While it will probably never be used to actually move the earth, the same techniques could be used to move things (spacecraft, asteroids for raw materials, etc..) without vast expendature of fuel as is currently done, where much of what we do is the brute force method. I read a paper that described how to get a spacecraft to the moon using less energy than a homan transfer (the most efficient way we currently change orbits). The method used the fact the earth, sun, moon system is a chaotic 3 body system. The drawback was that it took years to get the spacecraft to the moon.
Sorry that was so long winded.
Sean Roberts
Hey, I like this planet...now if people would just stop indulging in such conspicuous consumption, and dumping their shit all over the place, maybe it would be a decent place to hang around.
It's 10 PM. Do you know if you're un-American?
...before the Vogon Constructor Fleet destroys the planet to make way for an intergalactic bypass!
(Hey where's my thumb??)
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Do daemons dream of electric sleep()?
Couldn't the whole thing be solved a lot more simply? All we have to do is dig on the sun-side of the earth and put it on the far side. The chinese have been getting ready for this for a long time. You see they have been building a huge population and a huge sidewalk (actually meant to span half the earth). Then they are planning on setting up a gigantic chinese fireline to pass buckets of earth from China to the western tip of Africa.
there are 2 kinds of people. those who divide people into 2 kinds, and those who don't.
This idea sounds like these guys have been watching too much Doctor Who.
Gravitational friction isn't the correct term. The Moon is moving away from earth because of tidal forces. You are correct though that it is because of the interaction with the oceans.
What is happening is the tidal bulge that is created by the moons gravity leads the moon slightly. This inhomogeneity gives a slight non-radial component to the gravitational force the earth exerts on the moon. Since the force is leading the moon, it pulls it along in its orbit just a bit, this speeds up the moon which in turn causes the orbit to move outward.
The moon however will not escape the gravitational pull of earth. The lunar orbit will eventually become stable. When it does the orbital period of the moon will be exactly equal to the rotational period of the earth (the same forces that are speeding up the moons orbit are slowing down the earths rotation - in fact a day on earth used to be much shorter - I think I remember reading that it was about 14 hours during the period of the dinosaurs). This matching of orbital period to rotational period is common, it is called a spin orbit coupling. The moon is already coupled to the earth - thus the orbital period of the moon is almost exactly equal to its rotational period, that is why one side of the moon always faces the earth. Mercurys orbital period is also coupled to it's own rotational period, in this case it isn't 1:1 but 2:3 (2 rotations every 3 orbits about the sun). Plutos orbit is also coupled to Neptunes, this is why despite the fact Plutos orbit crosses Neptunes, they will never collide, because there orbits are coupled in just the right way.
By the way when the earth moon system becomes stable a month will take exactly 1 day. However by then a day will be approximately 1000 hours. Just like one side of the moon always faces the earth, one side of the earth will always face the moon, and anything on the other side of the earth will never see the moon, and the moon will always be in exactly the same part of the sky for those that can see it.
Sean Roberts
I vote for California.
If it ain't broke, it doesn't have enough features yet.
Perhaps you ought to move off the planet, just in case. Oh, and take Alec Baldwin with you.
The gravitational pull between the two bodies would indeed produce a force pulling the two "towards eachother".
However, the idea is that it comes by with the right velocity and angle that it shoots right past, and just kind of pulls out our orbit a little bit.
Basically... the asteroid would slow down, and we would speed up....but not enough so that it would actually come into our orbit or even hit us...it would continue right along its path.
-Steve
"I opened my eyes, and everything went dark again"
Three cheers for forward thinking, but if we're still tethered to a single planet a billion years from now, then something is drastically wrong. If we develop the space technology neccessary to actually harness an asteroid and make it go wherever we want it to, wouldn't that indicate a level of technology that would permit us to live on any damn planet we choose? We should be all over the freakin' galaxy by the time this becomes an issue. (Provided that we haven't become extinct via some other means - including by our own hands.)
This is not a Fugazi
Of course, there is no conceivable way anyone alive could imagine our technology in the year 1000002001. Maybe we won't have to move the Earth... we'll just turn down the sun!
Mr. Ska
I slit a sheet
A sheet I slit
Mr. Ska
Well.... I dunno whats sillier...your idea or the fact that I am actually going to explain why it wont work :)
When a person jumps, they exert a force against the earth. Now...the mass distribution of the earth changes a bit...and thus the center of gravity changes...so if aenough people did this in a way that produced a net force, the earth would indeed move away from them. (it would take quite a few for this change to even be measurable.
However... unless they reach escape velocity... the gravitational force between them and the earth will pull them back... exerting exactly the same magnitude of force against both, but in an opposite direction.
Basically... the center of mass for a closed system (and in this case, we are indeed talking about a closed system) will not change. You need an EXTERNAL force to change the velocity, internal forces always cancel out.
Now...if you could get the entire population of china to jump AND reach escape velocity.... that would be quite a different story...however... they may not fare too well.
-Steve
"I opened my eyes, and everything went dark again"
If this is ever going to be done, it would have to be a unanimous vote from every country, holding majority elections in the country to decide the nation vote. Because this could easily fuck up and you don't wanna fuck up the planet unless everyone agrees it will be fun.
Not bloody likely.
I don't there there is any law, proposal or suggestion that could get unanimous consent on this planet. Even the most obvious thing has to be debated by two "sides". Even when one side of the argument is just plain silly. (Certain Republicans come to mind...)
Reality has a liberal bias
Lets see...
Asteroid hitting the earth,
Another Ice Age,
Global Warming,
Economic Recession/Depression,
"Grey Ooze",
World War,
etc...
These will all likely happen within a million years, and there are scientists worrying about stuff that will happen in a billion years?
My guess is, they'll all give themselves a coronary worrying about this stuff in about 2 years.
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Good quote, too many chars. Seriously, the slashdot 120 char limit sucks!
- The Earth-Luna pair must be considered a double planet system. If these scientists expect to significantly alter the orbit of Earth, then similar plans must be taken to ensure that Luna's orbit is matched throughout this change. Any instability or gravitational pull on Earth must also affect Luna, due to its relatively near orbit.
- Without planning for this, assume that Luna will be affected by such a large asteroid even more so than Earth, or even less so, depending on exactly how they plan to use the gravitational slingshot effect. In that case, one of many outcomes might happen:
- Luna will be drawn closer to Earth and enter a nearer, faster, and possibly more eccentric orbit. This will wreak tidal havoc.
- Luna will be pushed farther from Earth and enter a slower and more eccentric orbit. This will also cause many problem.
- Luna's orbit will be unperturbed, but this is not likely.
- Luna will be ejected from its present orbit altogether, and become an unpredictable planet-like object with its own orbit. This clutters up the inner solar system immensely.
- Luna may collide with Earth.
- The inner solar system is a VERY busy place. We have three other planets (Mercury, Venus, and Mars) to worry about. Significant research has been done (and I don't remember by whom, but it was very well computed and presented) to show that the Earth-Luna system plays a stabilizing role in the orbits of Mercury and Venus, and also Mars to a lesser degree. The conclusion by this astronomer was that were Earth in a different location, then the orbits of Venus and Mercury would eventually destabilize and become unpredictable in a short time, possibly even tens of thousands of years.
- Some of the ramifications of moving Earth-Luna would mean similar effects upon Venus and also Mercury, over time. Any change to the gravitational balance of our solar system may cause these orbits to become destabilized or eccentric, and eventually lead to any of these outcomes, listed in order of likelihood:
- planetary collision with Sol
- planetary collision with another planet
- planetary collision with Earth-Luna system
- planetary collision with Mars
- planetary ejection
- planetary collision with Jupiter, or capture by Jupiter
- any other possible catastrophe
- As mentioned before, the inner solar system is a very busy place. Thousands of asteroids, micro-planets, and comets have been discovered, some only within the last decade. Earth-Luna itself is subjected to periodic meteor showers (e.g., Perseid, Leonid, etc.) whose exact nature and orbital stability are unknown. Moving Earth-Luna might mean subjecting Earth to heavy bombardment from any one of these inner solar bodies. The consequences of such an impact/collision would be far worse than any perceived solar output delta, and would have much shorter-term and more catastrophic impacts upon Earth's biosphere.
- Finally, the outer solar system does exert measurable gravitational control over the inter solar system bodies. Jupiter is theorized to have played a stabilizing role in the formation (and further development) of the early solar system, with its near-circular orbit and huge mass. If Earth-Luna were moved, then the system might be gravitationally affected in a different way by the gas giants.
- Bode's Law has not been the end-all authority over planetary configuration, but there is a certain harmonic resonance seen in the orbits of the planets. Moving Earth-Luna would change and possibly destroy this resonance, which would change the nature of the solar system.
- Planetary stability in the current solar system configuration, over the very long term (>10,000,000 years) has not yet been proven! Astronomers are still working to solve the N-body problem with the data that we have about the planetary bodies that we know.
- The current cycle and mechanism behind global cooling (ice ages) is not completely known. We may be on the upswing from a recent ice age, and there is some evidence to prove this. If Earth-Luna is moved, this may drastically change the cycles and the weather patterns, even over the long term.
- The current Solar trends have been measured for a very short time (astronomically, only an eye-blink) and cannot be predicted or planned with any great certainty. We still know too little about our own sun to know whether its output delta is cyclical or constant. Also, we know too little about the surrounding space around the heliopause to be able to predict how extra-solar galactic space (and matter) may affect Sol in the long-term.
- Europa appears to be vacant.
These are just some, but not all, reasons against messing with the orbit of Earth-Luna. My facts may not be complete or entirely accurate, but I don't really think this is a good idea. Our Solar system is not a landscaping project -- we just shouldn't be moving the big rocks around until we really know how everything will be affected.Just because people read Larry Niven's books (which are generally very good, by the way) about the Puppetteers moving their homeworlds away from their sun, doesn't mean it can actually be done. There are perfectly good places to settle and colonize that don't involve moving planets and wreaking havoc.