Iron

[ClubMed]

What is the origin of Iron on earth? Is it extra terrestrial ?

Is there any research that points to the origin of iron on earth as having come from a comet* for example?

*Edit: spelling.

Iron is one of the most prevalent metal elements in the universe actually. Most asteroids are composed of nickel and iron.

[nomaxim]

I think comets are mostly made up of ice. The core of the Earth is iron, hence the magnetic field.

[ben-the-slacker]

I agree with Whir. The asteroids and meteorites that clumped together to eventually form earth were of iron-nickel alloy. Pure iron isn't dense enough to sustain the density of the inner core of earth. Hence the earth's inner core is believed to be iron-nickel solid. The outer core is liquid.

[ClubMed]

So does that mean the iron on earth has a foreign origin? (i.e. that it came from outer space?)

Is this a generaly accepted theory in scientific circles?

We are all made of stars, CM. So yes, everything the earth is composed of has come from somewhere in space. Our solar system after the sun formed was nothing more than an acretion disc. Slowly the matter clumped together and formed the planets. At least that's the theory. God could've just snapped his fingers too, right?

Actually, Ben, they've been proposing that the core is crystaline iron as that's the only way it'd be able to do what it does. Or something. I'd have to go dig to find the article again.

[nomaxim]

Yea, pretty much.
Our entire solar system formed from matter that floats around in space.
Space is not a complete vacum, there are free atoms moving all over the place and they gather into clouds of gas and dust. Gravity will pull the gas and dust together and in a roundabout way finally develop into suns, planets, and such.
Damn, forgot about nickel.

I'll look around for some links.

Try this Googled; solar system formation.

[Theophylact]

Iron is at the bottom of the curve of binding energy: fusion of lighter elements releases energy until you get to iron-56; fissioning heavier elements releases energy until you get to iron-56. So if no other processes were going on, everything in the universe would tend ultimately to wind up as iron.

Fortunately for elemental diversity and our existence, there are other processes that are endothermic. The elements heavier than iron are all thought to be the products of supernova explosions and the intense particle floods released by them.

By the way, the intense magnetic field of Jupiter is assumed to be produced by convection currents in its metallic hydrogen core; it has little if any iron.

[ben-the-slacker]

Originally posted by Whir
Actually, Ben, they've been proposing that the core is crystaline iron as that's the only way it'd be able to do what it does. Or something. I'd have to go dig to find the article again.

Ahh ok, darn geology teacher taught it wrong.

Mr. Chemist to the rescue!

Supernovae are handy particle colliders, so they say.

Actually, he probably didn't. The article I read was merely theory. We can only teach what we think we know, right?