Posted on 01/12/2019 3:21:15 PM PST by BenLurkin
Astronomers know our solar system better than any other, but they're still learning new ways in which it doesn't seem to be particularly normal.
Right now, the leading theory of planetary formation, called the "core accretion model," is tailored to explain what we see in our solar system — the only one we knew much of anything about when the model was developed. But the more planets we identify in other solar systems, the more we find they don't match the patterns of mass and orbital distances found here on our own.
Take, for example, the staggering size gap between Neptune and Saturn. Neptune is about 17 times the mass of Earth, whereas Saturn is far bigger at 95 times Earth's mass, according to NASA. In between, nothing. The core accretion model explains that gap with a mechanism called "runaway gas accretion."
…
There's just one problem: Astronomers have realized that other solar systems do host plenty of planets with sizes between these extremes, nicknamed sub-Saturns. A paper published in December in The Astrophysical Journal Letters and presented at the meeting compared 30 different planets identified by a specific technique with what scientists would expect to see based on the core accretion model. In that survey, they found the model doesn't match very well with reality.
That gives our solar system a new weird quirk — its missing sub-Saturns.
And the lack of such planets overall is because they're really hard to detect. There's only one technique powerful enough to identify planets that orbit beyond what astronomers call the "snow line," where loose material in an early solar system is far enough from its sun that light materials like water can freeze — the sort of neighborhood you need to search to find sub-Saturns.
(Excerpt) Read more at space.com ...
Astronomers know our solar system better than any other, but they’re still learning new ways in which it doesn’t seem to be particularly normal.
*ping*
The core accretion model explains that gap with a mechanism called “runaway gas accretion.”
...
So this is bad news for the “runaway gas accretion” model. Other models are still in the running.
If we allow sub-Saturns, then the semi-Saturns will be all “what about us?”
Then we’ll start hearing it from the demi-Saturns... I mean, it’ll never end!
It’s best to just not let it get started.
One Saturn has been plenty ‘nuff this long. It’ll just have to keep being enough.
We used to have one in between sized. It’s a pile of orbiting rubble now.
jupiter has wandered, with mars and other moons
having surfaces heralding massive impacts.
perhaps from the missing sub-saturns?
Then Pluto will want be a planet again. It would be chaos.
I purchased and still enjoy the “Great Courses” lecture series “The Origin and Evolution of Earth” led by Dr. Robert Hazen Ph.D. on the origin of our Solar System and Earth (2013). Now, here, it is a mere 6 years later and some of what he voiced so confidently has been made rather dicey in the current exoplanet discoveries. The item I find most in discrepancy from his 2013 lectures is his then-current accepted science description of how the early Solar System had the strengthening Sun sweep the lighter elements from the inner planets while allowing the Ice Giants (Jupiter to Neptune) to retain their Hydrogen & Helium atmospheres.
Now the exoplanets surveys have found ‘Jovian’ (Jupiter cousins) planets nestled close to their suns/stars while acceptable papers have been presented at AAAS and other prestigious conferences to talk about a ‘wandering Jupiter’ coming in close to Sol before moving back out to its current position with the effect of elimination ‘Super Earths’ of double size in the same orbit.
I am willing to accept that I may be wrong in the future BUT the “Rare Earth” hypothesis seems to me to be ever more pertinent as we discover more of our universe.
Jeeze, just when you thought the science was settled!
Easy answer. They stopped producing “Saturn” cars many years ago. Ergo, no more Saturns out there anymore.
I thought ALL science was settled.
Would an asteroid be a semi-hemi-demi-Saturn?
And don’t piss off Mars. Jeez, we’ve had enough of those bloody Martians. Coming down here and laying waste to the planet and all that.
Who cares?
Well spoken.
Certain to leave an impression for those who read it.
I'm sorry. Read what?
The total mass of the asteroid belt between Mars and Jupiter equates to about 4% of Earth’s moon. The four largest objects, Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea, account for half of the belt’s total mass, with almost one-third accounted for by Ceres alone.
Thanks fieldmarshaldj.
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Astronomers know our solar system better than any other, but they’re still learning new ways in which it doesn’t seem to be particularly normal.
Consensus thinking or how to fit the fact into the theory ...
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