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Sunday, November 16, 2008

We are star dust

Spot the difference:


9 comments:

dearieme said...

My first thought is that it's utter bollocks, since we are mainly water and so must contain lots of hydrogen. My second thought is that the vertical axis isn't defined, but if it is "% by mass" that MIGHT explain the low hydrogen value: slippery, light atom, Johnny hydrogen. Of course, to discuss atomic composition in mass terms might be thought to be bloody stupid (or dishonest).

Sackerson said...

Hi, DM. Yes, it's by mass. Just thought it curious how unrepresentative we are of the Earth, in chemical terms. Mind you, all those heavy elements in the earth were also created in exploding stars, weren't they?

And why do we find heavier elements (uranium, gold etc) in the earth's crust? Why isn't it all in the core? Was it brought to the surface in the meteorite cataclysm that created the Moon?

Anonymous said...

No Iron in the human body?

dearieme said...

The stupidity/dishonesty barb was not aimed at you, Sackers, but at your source. Just thought that I'd better make that clear. Stupid or dishonest not to, really.

dearieme said...

Of course, since we are not representative of Mother Earth, we must be pollution, I suppose. Like the oceans.

James Higham said...

Er ...

Old Prof said...

Based on imaging of the rainforest, it would appear that life is the most efficient way of generating entropy, i.e. dissipating the Sun's energy. We're just the Earth's sweat.

As for elements, everything up to iron is generated by fusion in typical stars, giving net energy. The elements after that come from supernovae. I believe that a lot of the heavier elements in the crust are from a) the original accretion that formed the Earth; b) volcanic and tectonic processes that raise stuff to the surface; and c) from meterite impact (see the K-T boundary)

Sackerson said...

Anon - it's part of the 0.55% not shown.

DM: imperfect labelling still my fault, I'm afraid, I'm still learning how to do graphs in Windows Vista.

James - I was just taking a moment to wonder at the world.

OP: slowing entropy, we are the way the universe makes the pleasure last. As to the heavy metal stuff, I'd have thought the original accretion material would have resolved itself so that the densest sank to the centre, where the volcanic processes don't reach. So possibly it's the other reasons - major meteor impact busting the earth open, and minor impacts adding to the crust.

Old Prof said...

If I recall correctly, the Earth gains 1 million tonnes per day of meteoric dust, quite a lot of it heavy metals. There's also no reason why all of the heavy stuff would go to the centre during accretion, although most did. Think of the high angular momentum of the later stuff. After all, the Earthe was spinning an orbiting during the process.