[FUBAR-BDHR]

Picking up cosmic dust?

[The E]

Earth is growing at a rate of a millimeter per 10,000 years.

I call ^{[citation needed]} on that one.

[iamzack]

Earth is growing at a rate of a millimeter per 10,000 years.

This sounds very familiar somehow.

[Daniel P]

Earth is growing at a rate of a millimeter per 10,000 years.

This sounds very familiar somehow.

I got it out on some book I read years ago.

[watsisname]

Meteorites.  The solar system never truely stops forming.

But anyway, even if that "growing earth theory" were true, what's the point to it?

[The E]

Yeah, well, but most of them burn up in atmosphere, most of the resulting dust either stays in the Atmosphere or rains into the Oceans. For this stuff to affect a planetary body with a radius of ~6400km, there would have to be rather more of it than we are seeing, I believe. Plus, estimates on that scale (a millimeter per 10000 Years?) are far too small to be accurate, really. (Makes me wonder how they arrived at that conclusion in the first place)

[watsisname]

It's not measured (there's no way in hell to do so), so it's calculated.  The average rate of material hitting Earth can be figured to some degree of accuracy from observations of meteor showers, bollides, and impact craters from the past.  Figure the volume of that material and then compare with the volume of the Earth.  It'll be a ridiculously small number, but it's still a number.

[blackhole]

Given a millimeter every 10000 years, and the fact that the earth is about 4.5 billion years old, this comes out to:

45000000000/10000 = 4500000 mm, or 4500 meters, or 4.5 kilometers. Given a current radius of 6400 km and the volume of a sphere being 4/3(pi)r³, we get an initial volume of 1095751614231813000000, and a final volume of 1098066219443523500000, which is a difference of 2314605211710521300, or 0.2% of the earth's total volume.

Put more simply, 4.5 km is a 0.07% change in the earth's diameter over 4.5 BILLION years.

It doesn't f-cking matter

[Flipside]

Worse still, it only takes a few really potent volcanic eruptions to balance out the difference.

[Mefustae]

Worse still, it only takes a few really potent volcanic eruptions to balance out the difference.

Not to mention all the material that makes up the satellites, probes, and other junk we've shot into orbit. An amount far too small to even bother calculating, but that's still mass that has been completely subtracted from the Earth.

[redsniper]

until their orbits decay

[Mefustae]

until their orbits decay

Well, yeah. But then you've got things like Voyager probes. We ain't getting those back any time soon, what with the Klingons blowing one up and the other falling into a black hole and merging with a super-advanced  race of sentient machines.

[Flipside]

Not to mention the junk we've left laying around on the moon and Mars, it's all tiny, but it all adds up, in fact, no longer being a closed loop is one of the major resource concerns about colonizing other planets, hence all the experimentation with building and growing things in space. The first priority of any colony would be to become self-sufficient.

Edit: Oh, and he forgot Ice Ages.
And I love the way Antarctica jigs around and changes direction twice in order to avoid hitting South America

[Pred the Penguin]

From now on, anything that I consider idiotic will get a reference to this "conspiracy" theory.

[Flipside]

One thing I will say is that when the Earth reached its smallest size, the first though that crossed my mind was 'a little bit bigger and that would make a good planet for the MediaVPs'

[Bob-san]

Dear Sara,

I don't really know how to tell you this, I’m joining the Convent. I think I realized it When i threw out your sock drawer at the mental hospital and I saw you hit on my other girlfriend. I'm sure you're open enough to understand that your driving sucks. I'm returning the couch cushions to you, but I'll keep your car as a memory. You should also know that I told in my confession today about the moose poaching and you ruined my attempts at another world war.

Please don’t hurt me,
Thomas

 

[Black Wolf]

We probably lost way more mass via impact ejecta during early formation than we ever have or probably ever will put into space (especially if you count the moon, which the most accepted current theory states is just a big chunk of ex-earth), but of course, that was all more than balanced by the massively increased additions that those impacts were causing back then vs. now.

But anyway, even if that "growing earth theory" were true, what's the point to it?

Well, if it was correct (it isn't), then we'd need to totally redefine our understanding of tectonics, which has been the defining broad geological theory of the past half century, and has explained pretty much everything about the gross formation of the earth. Granted, there are still a few areas that don't quite add up (mantle plumes and hotspots being the big ones AFAIK) but they really just require slight refinements of the theory to fit that we're yet to properly confirm.

But, as i say, it's not true. We had the epanding eartn theory explained to us in second year as a sort of humorous aside - it's quite literally a joke in the broader geological community. As has been explained, you can pretty much puncture it with subduction zones.

[Bob-san]

We probably lost way more mass via impact ejecta during early formation than we ever have or probably ever will put into space (especially if you count the moon, which the most accepted current theory states is just a big chunk of ex-earth), but of course, that was all more than balanced by the massively increased additions that those impacts were causing back then vs. now.

But anyway, even if that "growing earth theory" were true, what's the point to it?

Well, if it was correct (it isn't), then we'd need to totally redefine our understanding of tectonics, which has been the defining broad geological theory of the past half century, and has explained pretty much everything about the gross formation of the earth. Granted, there are still a few areas that don't quite add up (mantle plumes and hotspots being the big ones AFAIK) but they really just require slight refinements of the theory to fit that we're yet to properly confirm.

But, as i say, it's not true. We had the epanding eartn theory explained to us in second year as a sort of humorous aside - it's quite literally a joke in the broader geological community. As has been explained, you can pretty much puncture it with subduction zones.

Which theory exactly says that the moon was a part of the earth? To me it seems very unlikely--to have a satellite so large, so stable, and so close all at the same time. Listening to theories and all, it makes most sense to me (who isn't a physicist or anything) that a collision occurred and the big stable and close moon was the remnants, perhaps of that other planet's core. Then again, there's intelligent life on Earth, so using that as a comparison, I suppose a microplanet could, by freak occurance, be trapped as our satellite.

[The E]

One of these? Especially the "giant impact"-Hypothesis.

[Black Wolf]

In a nutshell, the idea is that way back when (as in, after the ball of rubble phase, but probably not too long after) while the earth was still heating up and the solar system was still full of junk, something roughly the size of mars collided with the earth, and pretty much ****ed the earth's **** right up, knocking off the debris that would eventually form the moon.

[EDIT]Yeah, beaten to it. Giant impact is the proper name.