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namsag
Could always build a gigantic conveyor belt system to guide it away 
If an asteroid is on collision course with the earth.
- Thread starter joe-90
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Lincsbodger
Could always build a gigantic conveyor belt system to guide it away
Like the Escalator to Nowhere
and the Giant Magnifying Glass, and the Popsicle Stick Skyscraper?
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Mickymoody
On the programme 'The sky at Night', Patrick Moore said that there was an asteroid on a pretty close tradjectory with Earth, around 2070 ish? or even earlier? Now, if they got it wrong, and it impacts, then we all die, but if it's a near miss, then surely it will affect gravity, as the moon does the oceans, so likely to have mass flooding. It's going to happen at some stage. A recent spacecraft has landed on an asteroid, collected samples, and returned to earth, so theoretically, the asteroid can be diverted; but if you got all the jet engines in the world thrusting against the rotation of the earth, could they slow/stop the rotation?
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Lincsbodger
No, because the rotational kinetic energy (aka angular momentum) of the planet is absolutely colossal, and it would take the sort of energy you get in a planetary collision to change the spin, a few piddly jet engines placed by man wouldnt affect it.
They would actually, even one engine would slow it down. Given enough time it could even stop it. It might take a while and a few bobs worth of fuel though.
Why do we want to change the Earth's angular velocity - or was this a hypothetical question. You can have as many jet engines as you like but they won't change anything unless they are placed so as to throw material clear of Earth's gravity. One way to do it - hypothetically - is to fire projectiles out into space, never to return, along tangents to the equator.
You can have as many jet engines as you like but they won't change anything unless they are placed so as to throw material clear of Earth's gravity. One way to do it - hypothetically - is to fire projectiles out into space, never to return, along tangents to the equator.I don't know if the question was hypothetical, but my assertion was.
So to make it work you'd just need a completely dead Earth with no atmosphere and no outside forces acting on it......and a jet engine that works without atmosphere.
So to make it work you'd just need a completely dead Earth with no atmosphere and no outside forces acting on it......and a jet engine that works without atmosphere.
A jet engine that works without atmosphere is easy. It carries it's own oxidant and it's called a rocket engine.
What you have to do is propel something along a tangent and clear of Earth's gravity. Anything that falls back will cancel the effect you are trying to achieve. In theory, you could anchor a rocket engine somewhere above the atmosphere but it would be a lot easier to propel the engine itself out into space.
For what it's worth, there is one other way - and it's already happened. You let the moon's gravity do what it already does and pull the oceans about but you build dams to restrict their flow. And so the tides push against the surface of the Earth.
What you have to do is propel something along a tangent and clear of Earth's gravity. Anything that falls back will cancel the effect you are trying to achieve. In theory, you could anchor a rocket engine somewhere above the atmosphere but it would be a lot easier to propel the engine itself out into space.
For what it's worth, there is one other way - and it's already happened. You let the moon's gravity do what it already does and pull the oceans about but you build dams to restrict their flow. And so the tides push against the surface of the Earth.
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Profile of Earth approx 12,742 Kilometres mean diam'... Orbital velocity through space approx 107,200 Kph or 8.4 diam's p/h, shifts one whole profile in just over 7 mins... A pretty nifty moving target, we'll have to be very unlucky to cop a medium hit never mind a biggy.
This is from wickipedia and according to this we're well overdue. I'll be alright though...I've just bought a new umbrella.
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Lincsbodger
yea but...............
the distribution of solar large objects and the impact rate might be following a logarithmic distribution rather than a linear one, which make guessing when the next one will occur and bit hit and miss in the short (ie 10 million year) term.
If the oort cloud was originally distributed evenly throughout the solar system, the hit rate drops on a log scale as they stray bits get swept up and either impacted or shepherded into a harmonic orbit, like the asteroid belt.
It's thought that a lot of the big earth impacts come from objects in the asteroid belt that have been perturbed by jupiters gravity. The point is though no one knows when the next one is coming, just that it will. There might even be one with our name on it just a few tens of millions of miles away, as we speak.
sooey said:
Here's a hypothetical question: If you saw a roulette wheel come up red ten times in a row, would you say that a black was well overdue?
Some would say that, by the law of averages, the next one really ought to be black - but that's not how it works.The probability of a truly random event happening does not depend upon how long it's been since the last one. That would only be the case if some cyclic phenomenon was at work. Maybe there is and maybe there isn't. You'll have to ask an astronomer.
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