We May Have Jupiter To Thank For the Nitrogen In Earth's Atmosphere 46
An anonymous reader writes: Nitrogen makes up about 78% of the Earth's atmosphere. It's also the 4th most abundant element in the human body. But where did all the nitrogen on Earth come from? Scientists aren't sure, but they have a new theory. Back when the solar system was just a protoplanetary disk, the ice orbiting the early Sun included ammonia, which has a nitrogen atom and three hydrogen atoms. But there needed to be a way for the nitrogen to get to the developing Earth. That's where Jupiter comes in. During its theorized Grand Tack, where it plunged into the inner solar system and then retreated outward again, it created shock waves in the dust and ice cloud surrounding the sun. These shock waves caused gentle heating of the ammonia ice, which allowed it to melt and react with chromium-bearing metal to form a mineral called carlsbergite. New research (abstract) suggests this mineral was then present when the Earth's accretion happened, supplying much of the nitrogen we would eventually need for life.
Not the only planet (Score:5, Funny)
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I don't believe the expansion of the universe makes any notable difference on the scale of a solar system.
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metric expansion in GR doesn't cause every distance to increase evenly That's exactly what it does.
No, it does not. Wikipedia [wikipedia.org] among many other write ups on the topic address this, because it is a common question why galaxies and the solar system. If you don't like Wikipedia or pop-sci sources, classic GR textbooks like MTW's Gravitation spell this out too.
Something like a yardstick isn't affected because if you magically stretch the space between every atom they will go back to their original spacing like a rubber band, releasing a bit of heat. If you magically stretch a solar system, the planets will shrink back to their original diameters for the reason above, but their orbits will stay stretched, and even become larger because the orbital speed is now too large.
There is nothing special about gravity versus other binding forces. Inertial effects exert no forces on bound objects, whether bound by gravity or other forces. Expansion due to a pressure term like vacuum energy can exert a force, but o heat is gen
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But Jupiter is massively massive, to misuse English. It's hard to believe all those small asteroids and junk would have enough bulk and momentum to make a difference on it.
Was there a lot more junk flinging around back then? I don't get it.
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This seems backwards; I'm missing something. Remember, I'm asking about Jupiter moving back out, not in toward the sun (which the article suggests is from friction with dust etc.). Other objects would have to lose orbital momentum for Jupiter to gain. Jup moving out would push the space junk inward, not outward.
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The total angular momentum of all solar system objects remain the same, correct? So if we ignore those flung out of the solar system for now (assuming it's not a signif. factor), if Jupiter increases its angular momentum (moves "outward"), then a good many objects will lose angular momentum to counter. Where did it go? Do many "long orbit" objects that once had a semi-circular orbits now have highly elliptical orbits (as many comets do)?
Re:Saturn pulling Jupiter (Score:5, Informative)
Nothing ever gets pulled closer, except that something else gets thrown further away in equal measure, anything else would violate conservation of momentum. This page give a bit of an overview: http://www.boulder.swri.edu/~k... [swri.edu]
As I understand it the idea is that they were acting within a relatively dense gas-and-asteroid cloud rather than the modern vacuum. Jupiter was moving inwards as it scooped up gas and asteroids from the inner system, launching most of that material into the outer system. And miniscule Saturn was towed along in it's wake. Eventually the orbital resonance with an encroaching Saturn slowed and reversed Jupiter's motion, at which point they began scooping up the detritus that had been thrown outward on their inward journey and hurling it back inward again while they moved outwards, eventually moving outwards far enough that they could start scooping up the previously undisturbed outer-system cloud and hurling it inward, moving them even farther out than they had originated. And of course Uranus and Neptune had meanwhile been busy throwing more material inwards from the far-outer system as they performed their own migrations, further fueling the outward migration of Jupiter.
Think of it like a gravitationally powered rocket engine - every asteroid that does a gravitational slingshot around Jupiter transfers just as much momentum to Jupiter as it does to the asteroid.
Eventually Jupiter's orbit stabilized when it ran out of enough outer-system detritus to propel it further outward, while orbital resonance continued to propel Saturn even further outward at the expense of propelling Jupiter slightly inward, solidifying the new orbital position.
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There is a lot of nitrogen about (Score:2)
It is the seventh most abundant chemical element by mass in the universe [wikipedia.org], but most of what was on earth has evaporated away.
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Yes, but "in the universe" is a much different location than "in the narrow ribbon of proto-planetary material that formed the Earth". Hydrogen and Helium are by far the most common elements by mass, and yet there's very little of either on Earth, due in large part to the fact that they are too light to be gravitationally bound by such a small planet unless incorporated into other compounds.
Consider that a proto-planetary disc around a star would act as something of a centrifuge, causing stratification by
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Compared to the percentage in the universe? Absolutely. Otherwise the Earth would be ~75% hydrogen by mass.
Thanks Carlsbergite! (Score:4, Funny)
Re:Thanks Carlsbergite! (Score:5, Informative)
I'm not sure it's that ironic, since carlsbergite is named after the Carlsberg Foundation, which was set up by Carlsberg's founder.
Re: Thanks Carlsbergite! (Score:4, Funny)
No it's chromiumy
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Don't touch my Carlsbergite!!!!
Really ? (Score:1)
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Wow, not even reading the title. Congratulations, you have reached the pinnacle of Slashdot laziness.