What would it take to move earth

[oldunion]

Well i just watched episode 5 of space with sam neil, good series. and they had a ring that protruded from the Earth with a hot side and a cold side-earth was in the middle indicating the ideal/safe distance from the sun. Not in my lifetime will the sun come dangerously close to earth, but it will happen. So my question is, rather than fly humanity out to some place like Mars (which no doubt we will have conquered by then anyway), why not detonate some extremely electromagnetic weapon above one of poles of earth. The charge of the burst would be say positive, so you detonate it above the positive pole of earth. If it was an unimaginably powerful burst, could the planet be moved from its orbit?

 

[Janus]

Well for one thing, the Earth doesn't have a "positive" pole. It has a North and South Magentic pole but these are totally different.
Two, you can't just produce a positive charge. Charge is conserved. so unless the device had a net poitive charge equal to that of the blast you wished to produce to start with, it couldn't produce a net positive charge.


Three, Any blast powerful enough to move the Earth enough would have dire consequences on the environment of the Earth.

Four, The poles would not be the place for such a blast in the first place. The tendency would be to alter the tilt of the Earth's orbit and not its size.

Actually, this problem of moving the Earth has been studied. It was found that it would be possible to move the Earth using the following method:

You find a fair sized asteroid and place it in an orbit that causes it to pass closely to the Earth such that the gravititaional interaction with it gives the Earth a nudge into a higher orbit. You then adjust the asteroid's orbit so that it repeats this close pass on its next orbit. Adjusting the asteroids orbit is much easier because it mass is smaller and you don't have to worry about effecting the asteroid's environment.

You just keep swinging the asteroid( or you could use a number of asteroids) past the Earth, nudging it higher and higher with each pass. Thus you slowly move the Earth out away form the Sun.

 

[matthyaouw]

In theory the asteroid idea seems posssible, but how would you go about the task of adjusting the asteroid's orbit so dramatically yet precisely?


A wee side note: Even if magnetically adjusting the world's orbit were possible, I believe the problem of flying cutlery would be truly terrific.

 

[Janus]

In theory the asteroid idea seems posssible, but how would you go about the task of adjusting the asteroid's orbit so dramatically yet precisely?

Possibly through some version of project Orion or even a large Ion engine.

Once you get the asteroid into an Earth orbit crossing orbit, it will take relatively small adjustments to make addtional passes. If we use several asteroids, you can have quite a long time span between passes to adjust each asteroid's orbit.

We've got a long time to develop the technology and quite a long time to pull it off.

Just for fun, I calculated the energy needed to move the Earth from its present orbit out to Mars' orbit, it worked out to some 1.4 X 10^33 joules.

Now consider that a one megaton nuclear blast generates 4.18 x 10 ^15 joules, and assuming that we had a billion years in which to move the Earth, this is the equivalent of detonating one 100 megaton bomb every 10 secs over that Billion years.(And that's assuming that all the energy of each blast went into moving the Earth) This pretty much precludes using any type of Earth based explosions to move the Earth.
Imagine the following scenerio:
The first blast goes off. In order for the blasts to remain properly aligned in order to maximize effect, the next bomb is placed some 4.4 km to the West so that, as the Earth turns, after ten secs it will be in the same position with respect to the Sun when it goes off. Subsequent bombs are spaced further along. After 24 hrs we are back to the location of the first blast, but not quite. Since the Earth is also tilted to the ecliptic, the new bomb site is over 250 meters to the North or South of the first bomb's position (depending on what time of year it is). As a result the Bomb sites will cover a band 23° on either side of the Equator.
It won't be long before everything between the Tropic of Cancer and the Tropic of Capricorn will be nothing by radioactive craters. The rest of the world wouldn't be in much better shape.

 

[CharlesP]

I had this problem in mind, and the asteroid solution is attractive because it "uses the Sun's gravity to amplify the initial push." But I was worried about the requirement that all the planet's periods match some multiple of Jupiter's. If that rule is violated chaos may set in. I don't know what will happen to the Earth's orbit. We can't move Jupiter too.

By the way please post your calculations. It is a wonderful thing to see a problem worked and not have to research it myself.