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We May Have Jupiter To Thank For the Nitrogen In Earth's Atmosphere
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.
We also have all this damn methane thanks to Uranus.
It is the seventh most abundant chemical element by mass in the universe, but most of what was on earth has evaporated away.
A bit ironic that without carlsbergite we might not be able to pour Carlsberg from a nitrogen tap.
Unless Ganymede gets there first, that is. :-p
Ezekiel 23:20
I bet they were drinking a lot of Carlsberg !
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...
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.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
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.
Table-ized A.I.
I don't believe the expansion of the universe makes any notable difference on the scale of a solar system.
Table-ized A.I.
Wow, not even reading the title. Congratulations, you have reached the pinnacle of Slashdot laziness.
metric expansion in GR doesn't cause every distance to increase evenly That's exactly what it does.
No, it does not. Wikipedia 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 generated in a yard stick, as without any movement, no work is done. You don't get things moving and things snapping back, some sort of oscillation, but just a shifted equilibrium position (if you push on a spring, it moves to a new point, and doesn't snap back unless you let go), but the force involved is proportional to length scale, and effectively zero compared to other forces at the human or even solar system scale.
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.
Table-ized A.I.
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)?
Table-ized A.I.
Well written.
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