
Is the Solar System Stable? (2011) - jsnell
http://www.ias.edu/about/publications/ias-letter/articles/2011-summer/solar-system-tremaine
======
dribnet
"There would be few fossil traces of these lost siblings of the Earth."

Our moon is a pretty obvious reminder of Earth's lost sibling Theia.

[http://www.astronomy.com/news/2014/06/new-isotopic-
evidence-...](http://www.astronomy.com/news/2014/06/new-isotopic-evidence-
supporting-moon-formation-from-earth-collision-with-planet-sized-body)

~~~
bjelkeman-again
That could be the kernel of a scifi story. What if Theia had life on it and it
spread to earth.

~~~
fideloper
Or it's unique properties + earth's in combination are the only reason why
life exists.

~~~
SoftwareMaven
There are theories putting Mars in that position: that early on, Mars was more
hospitable due to less water, and microbes eventually caught a ride on
something ejected from Mars via volcano or meteor impact.

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1ris
> After Newton discovered his famous laws of motion and gravity, he used these
> to determine the motion of a single planet around the Sun and showed that
> the planet followed an ellipse with the Sun at one focus.

It was more the other way around. Kepler found out that planets follow an
ellipse with the Sun at one focus. He formulated his 3 Kepler laws. Newton,
quite a while later generalised these laws into the so called Newton axioms.

~~~
iaw
Newton was the biggest jerk in science. We barely know what Hooke looks like
because Isaac destroyed every image of him after his death.

~~~
StandardFuture
Ugh ... besides the fact that your comment adds absolutely nothing to the
discussion, it is also stating (incorrectly) a possibility as fact.

There was one (not many) portrait of Hooke at the Royal Academy of Science
which at some point was destroyed while Issac Newton was President. It is
unknown whether the destruction of the portrait was directed by Newton or if
Newton just did not bother protecting it (Hooke had gotten into conflicts with
other scientists as well).

Thus, your comment in its entirety is a waste of space. I will be flagging it
as it is non-constructive to the discussion of the article.

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dnautics
_However, the presence of chaos implies that we can only study the long-term
fate of the solar system in a statistical sense, by launching in our computers
an armada of solar systems with slightly different parameters at the present
time—typically, each planet is shifted by a random amount of about a
millimeter—and following their evolution. When this is done, it turns out that
in about 1 percent of these systems, Mercury’s orbit becomes sufficiently
eccentric so that it collides with Venus before the death of the Sun. Thus,
the answer to the question of the stability of the solar system—more
precisely, will all the planets survive until the death of the Sun—is neither
"yes" nor "no" but "yes, with 99 percent probability."_

I wonder: How ergodic (this is likely a misuse of this word) is the system? If
there's a 1% probability of mercury crashing into venus over this time period
does that scale? If I run all 100 simulations for 10 times longer do 10 of
those hypothetical mercuries crash into hypothetical venuses(.99^10 ~.9)?

~~~
thret
I'd guess not. I think they ran the simulations out completely, until the Sun
died.

~~~
dnautics
they didn't do that. Tidal forces get weird as the sun starts getting larger
and really weird when the sun's radius exceeds the orbit of earth. Their
simulations did not take into account solar death (it's in the article).

~~~
thret
I stand corrected, thank you.

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pavel_lishin
Thank you! I assume this was posted in response to this comment:
[https://news.ycombinator.com/item?id=8089259](https://news.ycombinator.com/item?id=8089259)

~~~
jsnell
Well, not quite as a response since it is the same article, maybe more of a
re-post. I was really surprised by the conclusion, and thought it was
interesting enough to deserve wider distribution. Not many people will read
the comments section of a day-old post. Of course antognini's comment sold it
a lot better than the article's title, but that's the price of not
editorializing in HN submission titles :-)

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jnotarstefano
Sometimes the answer is "no, but it doesn't matter", as shown by two
professors at my University:
[http://www.nature.com/nature/journal/v357/n6379/abs/357569a0...](http://www.nature.com/nature/journal/v357/n6379/abs/357569a0.html)

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FatalLogic
I read a little more about this and was surprised to find out that the
gravitational pull of Venus on Earth is enough to produce a measurable ocean
tide up to 0.03 mm (very approximately).

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guard-of-terra
For some reason I think that stability is the least energetic state of the
solar system.

So it's unlikely to change statistically speaking.

As for violent changes like ejection of a planet, I'm not sure solar system
may generate that kind of energy out of planet movements. Unlikely if you ask
me.

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officialjunk
anyone know of a mirror? it appears down or removed.

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DINKDINK
On what time scale?

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personjerry
tl;dr: for the most part, yes.

~~~
coder23
If you are a planet, you are going to be ok.

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waps
TLDR: it isn't.

For a real explanation : [http://en.wikipedia.org/wiki/Three-
body_problem](http://en.wikipedia.org/wiki/Three-body_problem)

It's a typical chaotic system. Over the short term everything looks and
behaves VERY stable, but every 10 million years or so things align juuuuust
right and some major shift suddenly happens.

~~~
jpmattia
> _but every 10 million years or so things align juuuuust right and some major
> shift suddenly happens._

I haven't thought deeply, but a quick check of the Sun-Moon-Earth system seems
to disagree with this.

