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Author Topic: Can the wobble of planets warn us of asteroids?  (Read 2240 times)

Offline Expectant_Philosopher

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Can the wobble of planets warn us of asteroids?
« on: 26/12/2014 08:40:38 »
Can we utilize planets in the solar system as an advanced warning system of asteroid threats to earth?  Can we utilize the gravitational shifts to the outer planets as a remote sensor grid detecting the wobble induced on them by asteroid threats?  I had been thinking of the possibility of us sending satellites to outer spherical locations surrounding our planet distant enough to give us early warning of asteroids, by measuring the gravitational shift of the satellite.  Then it occurred to me we already have a constellation of satellites, namely, planets, dwarf planets and permanent large asteroids that could perform the same function.  We know where these objects are and where they should be in the near future and could detect shifts in their positions or orbital axis to extrapolate both size and trajectory of any large asteroid moving towards our sun.
« Last Edit: 26/12/2014 08:57:21 by Expectant_Philosopher »


 

Offline alancalverd

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Re: Can the wobble of planets warn us of asteroids?
« Reply #1 on: 26/12/2014 11:53:11 »
Yes but

1. The planets are very large in comparison with the minimum size of asteroid that would cause devastation, so you are looking for tiny wobbles, much smaller than induced by their moons and other planets.

2. Nearly all the solar planets orbit close to the plane of the ecliptic - less than 1% of the celestial sphere - and they are each only in one place at a time, so if the wobble was detectable, say, when the invading asteroid was within 1% of the orbital radius of a given planet, you would detect at best 0.01% of the really, really big threats.

With an enormous amount of luck, you might just get to detect something the size of Jupiter and the density of Venus, a few weeks before it hit us. The question is, would you want to tell anyone about it? Remember that the only fatalities attributed to Three Mile Island were road accidents caused by people fleeing the locality.   
 

Offline David Cooper

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Re: Can the wobble of planets warn us of asteroids?
« Reply #2 on: 26/12/2014 20:18:51 »
Yes you should tell people about it - lots of people (Mormons in particular) have bunkers stuffed full of food so that they can survive a decade without sunlight. Birds like ducks and parrots survived the impact that finished off most of the dinosaurs, so there is a good chance that human survivors will find something to eat once their supplies run out. Those who have a bunker of this kind should be able to apply to be on a "to-be-informed" list while everyone else could be kept into the dark, leaving the latter to enjoy an unexpected violent death instead of being given the chance to take something to send them to sleep first.

Edit: It might be a long slow freeze to death for a lot of people rather than a sudden violent one - it's believed that a large part of the Earth was pounded by boulders 65 million years ago when the KT event asteroid hit, but round the other side of the planet it was dust that fell.
« Last Edit: 26/12/2014 21:40:37 by David Cooper »
 

Offline alancalverd

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Re: Can the wobble of planets warn us of asteroids?
« Reply #3 on: 27/12/2014 09:20:46 »
So it's a good idea to tell the 5% who have some kind of survival strategy. But if the word leaked out (like "why haven't the Mormons showed up for work today?") what would the other 95% do?

http://en.wikipedia.org/wiki/Bart%27s_Comet
has the answer.
 

Offline David Cooper

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Re: Can the wobble of planets warn us of asteroids?
« Reply #4 on: 27/12/2014 18:13:09 »
The real solution would be to ensure that everyone has a good supply of food to get them through a decade of failed harvests and a bunker big enough to store the food (and water) and people while any bombardment of rocks is going on. In addition to that, we need underground zoos to preserve all the key species we need to restore a decent ecosystem reasonably quickly, and lots of seeds of things we can grow to get new food fast. We could have done all this long ago if we weren't flushing so much of our money down the toilet by fighting silly wars and building weapon systems to threaten each other with. If we're going to move out to other planets and star systems, our first move should be to dig in here to ensure we survive long enough to make it possible.
 

Offline alancalverd

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Re: Can the wobble of planets warn us of asteroids?
« Reply #5 on: 27/12/2014 19:19:22 »
Given the improbability of detecting anything smaller than Mars by the method proposed, even if it happened to be travelling in the ecliptic plane, I think we are looking at total extinction, not just a few years of bad harvests. You don't need to shift or distort the earth's orbit by very much to make it completely sterile for ever.

It's always a good idea to start planning from where you are, not where you'd like to be. So, if I detected an incoming catastrophe tomorrow, with a predicted arrival time of Christmas 2017, what would you advise me to do next?
 

Offline David Cooper

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Re: Can the wobble of planets warn us of asteroids?
« Reply #6 on: 28/12/2014 18:43:34 »
As I said before, ducks and parrots survived the asteroid that hit 65 million years ago. If they can survive an event of that kind, why shouldn't we? Mammals that lived in burrows also survived and evolved to become us - we've been through this before. The key thing is to dig in to avoid blast damage and to store food so that you don't starve to death in the short length of time before it becomes possible to grow new food. It takes a few years for all the dust and H2SO4 to rain out of the sky, but it will always rain out before too long and life will recover. If our species was just a little bit more intelligent, it would be collectively preparing for this, but sadly it's being left to individuals to do this for themselves.
« Last Edit: 28/12/2014 18:50:37 by David Cooper »
 

Offline David Cooper

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Re: Can the wobble of planets warn us of asteroids?
« Reply #7 on: 28/12/2014 18:57:19 »
It's always a good idea to start planning from where you are, not where you'd like to be.

Isn't that what I'm talking about? Don't wait until you see the asteroid of doom coming your way, but anticipate it before you even know it exists. We are where we are now and should plan now rather than waiting until there's next to no time left to react.

Quote
So, if I detected an incoming catastrophe tomorrow, with a predicted arrival time of Christmas 2017, what would you advise me to do next?

Three years should be enough to build a bunker, but there would be a food shortage as everyone starts hoarding large quantities of it, leading to starvation in many parts. One option would be to buy weapons and to rely on eating the supplies of other people who are better prepared than you, but they'll be buying weapons too, so it isn't a safe option - it's much easier to defend than to attack. Realistically, you've left it too late if you wait till you see an asteroid coming and you're going to struggle.
 

Online jeffreyH

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Re: Can the wobble of planets warn us of asteroids?
« Reply #8 on: 28/12/2014 23:23:50 »
The asteroid would just speed up the process of destroying the habitat of planet and save us the effort. Simply by doing nothing and consuming ever more resources we will end up with the same result eventually. Is a slow death better than a quick one?
 

Offline alancalverd

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Re: Can the wobble of planets warn us of asteroids?
« Reply #9 on: 29/12/2014 00:06:27 »
Best estimates of the KT asteroid diameter seem to be about 15 km. This would almost certainly not be detected by the method proposed, which requires something with about 108 times that mass. Not a recoverable event.
 

Offline David Cooper

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Re: Can the wobble of planets warn us of asteroids?
« Reply #10 on: 29/12/2014 19:19:10 »
The Earth's been hit before many times, but most of the action happened very early on before there was any life that we know of. Theia, assuming for the moment that this Mars-sized object existed and hit the Earth, melted the whole surface right down to the depth where it was already liquid, so you clearly can't survive an impact of that size by digging in, but asteroids and comets are tiny compared to that, and they're the real threat. Such impacts are survivable, even if they knock down every last tree, just so long as we don't go into a long snowball Earth phase. (I wonder if that could be prevented by releasing lots of methane into the atmosphere or if it would be too full of dust for there to be any gain.) So long as there isn't a total freeze over, we can grow new forests fairly quickly, and we would want to begin by growing food forests (PDF on that subject (for anyone who's keen to learn about sustainable food production which doesn't need pesticides, fertiliser or hard work): https://drive.google.com/file/d/0BznRIYxR0GnLcEhBbXc1OTVwZVU/view?pli=1) which would provide a return after just a few years. All that's needed is for daylight to return as the atmosphere clears. We need supplies though of all the things we need to plant, and that means the government should be building and maintaining bunkers containing tree nurseries and the like, all designed to keep going for at least ten years after an impact.

I really don't understand why you're so keen for us not to give ourselves a fair go at surviving the survivable impacts on the basis that there could be one that's just too big to survive. It won't be much fun being wiped out by something smaller that it could easily have been survived. It's like refusing to wear a seat belt in a car because a lorry might fall on top of you and crush you flat. The possibility of a rarer, more severe impact is never a good reason for not guarding you against 99% of the potential hazards which could take you out. We need to dig in.
« Last Edit: 29/12/2014 19:23:23 by David Cooper »
 

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Re: Can the wobble of planets warn us of asteroids?
« Reply #10 on: 29/12/2014 19:19:10 »

 

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