Tiny Pebbles Built the Gas Giant Behemoths

astroengine writes: Scientists have long puzzled over how gas planets like Jupiter and Saturn got to be so big. Current theories suggest the cores of these behemoths are comprised of mini-planets, some 62- to 620 miles in diameter, which collided and gradually merged together over time. But computer simulations show this process is more likely to produce hundreds of Earth-sized worlds. Instead, a new study suggests "slow pebble accretion" is a more likely process.

Just say

[MichaelSmith]

100 to 1000 km

Re:

[turbidostato]

"some 62- to 620 miles in diameter"

My thought too.

"Wow! Planetary physics must be quite advanced if they can set such a precise margin!" Wait! or else... they *are* rounding up, only not in miles and astroengine is just making up numbers out of his ass.

Re:

[Rob Bos]

brought to you by the same people who gave us 591ml bottles of liquid and 454g bricks of butter.

I hope they find it annoying to be on the other side for a change.

Magnetism

[Henriok]

Studies have also shown that magnetic forces might count for the majority of clumping of matter in sizes smaller than regular rocks. On those scales gravity doesn't do much, but magnetism can do plenty. And it wouldn't be strange for protoplanetary matter is magnetized since it's whirling around in the Sun's magnetic field.

Re:Magnetism

[The Evil Atheist]

Magnetized protoplanetary matter, how do they work?

Re:

[wonkey_monkey]

How is planet babby formed?

Re:Magnetism

[Overzeetop]

When two planets truly love one another...

Re:

[Rei]

Not sure whether this [pbfcomics.com] or this [pbfcomics.com] is more appropriate ;)

Re:

[Viol8]

Well it would only be some metals that could be magnetised, not everything. But they could form small cores which then by gravitational accretion did the rest.

Also static electricity has been mooted as a good way for dust grains to clue themselves together.

Re:Magnetism

[Rei]

Even stony asteroids contain grains of metallic iron. Iron asteroids are, of course, predominantly iron-nickel alloy. And some of its oxides are even better candidates - most notably, magnetite. I was very surprised when I found that random pieces of basalt from my land were showing an easily measurable magnetic field, until it occurred to me that some percentage of the grains that make it up will naturally be magnetite.

Re: Magnetism

[Anonymous Coward]

Dusty plasmas can be magnetized, and just require situations where the magnetic field is strong enough (or other effects weak enough) that the charged dust particles (or even just the smaller species) are affected significantly by the magnetic field. Look up what it takes for a plasma to be called magnetized, and see it has nothing to do with which elements are present.

Re: Magnetism

[Anonymous Coward]

It isn't just magnetism, but a combination of magnetism and gravity. Gravity is plenty strong enough to affect things on that scale, but the problem is you end up with stuff orbiting in disks and eddies with no easy way for that material to shed momentum. Collisonal friction is slow at exchanging momentum compared to estimates formation times and observations of current accretion disks. However, the magnetorotation instability allows for quicker exchange of momentum, and for some material to move inwards (s

62 to 620?

[Anonymous Coward]

Without reading the article, I can guess that the original says 100 to 1000 km. When the write that they are giving just an idea of the diameter, so you can write 100 to 1000 miles. It is just a bit off, but the magnitudes are roughly the same and you don't get a false impression on the precision they had when they did the simulation.
Or just use km and don't convert them to miles.

Re:

[Viol8]

Its also kind of insulting that submitters feel the people on a technology and science site are too stupid to understand distances in kilometers.

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[Viol8]

Anyone in science and tech who is unfamiliar with the metric system is in the wrong career.

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[KeensMustard]

Perhaps the author is unfamiliar with metric but it does seem odd to assume that the readers of Slashdot would be unfamiliar with a system of measurement that most of us use every day. Even those of us who don't you would think would have a reasonable grasp of it.

Clarity

[jbmartin6]

Ohhhhh, sixty TWO miles! That's why my gas giant never worked!

Tiny Pebbles

[wonkey_monkey]

Tiny Pebbles Built the Gas Giant Behemoths

I'd been wondering what Tiny Pebbles had been up to since he retired from rap music.

Re:

[wonkey_monkey]

Damn, should have played it through to the end:

Tiny Pebbles Built the Gas Giant Behemoths

But they kicked him out of the band after their disastrous tour of Asia, and now he's suing for the royalties.

Sure It Wasn't Bam-Bam??

[zenlessyank]

Pebbles doesn't seem to be as strong and work-centric as Bam-Bam.

Don Ho

[boristdog]

Does anyone else now have a Don Ho earworm?

"Tiiiny Pebbles...In my planet..."