Re: Earth-grazing asteroids as a military resource

On 12/03/2025 3:17 am, Martin Brown wrote:

On 11/03/2025 13:34, Bill Sloman wrote:

On 11/03/2025 9:18 pm, Martin Brown wrote:

On 06/03/2025 16:44, Bill Sloman wrote:

On 6/03/2025 10:54 pm, Carlos E.R. wrote:

On 2025-03-06 04:06, Bill Sloman wrote:

On 6/03/2025 1:45 pm, Carlos E.R. wrote:

On 2025-03-06 03:05, Bill Sloman wrote:

On 6/03/2025 8:28 am, Dave Platt wrote:

In article <vq8jtq$299g5$1@dont-email.me>,
Bill Sloman  <bill.sloman@ieee.org> wrote:

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There is a limit to haw far into the future we can predict the trajectory of a comet or asteroid. It depends how well the orbit has been determined and how close it gets to any of the other big solar system bodies. Jupiter serves as a cosmic hoover by slingshot effect putting things into orbits that typically intersect with it or get flung much further out. Shoemaker Levy 9 famously suffer that fate

That insight has been formalised as a claim that the planets' orbits are chaotic over longer time scales, in such a way that the whole Solar System possesses a Lyapunov time in the range of 2~230 million years.
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https://en.wikipedia.org/wiki/Stability_of_the_Solar_System

 I think Ovenden's conjecture is probably more likely to be true in the sense that although we can't exactly predict things we can put quite good bounds on how far out of kilter things can actually get chaos wise in the solar system (barring a close encounter with a passing star or other seriously massive object shaking things up).

It is still a conjecture.

His conjecture is pretty much that the big guys are locked in resonant orbital patterns that avoid each other as much as possible. It seems to hold equally well for moons of planets as well as planets of suns.

The suggestion that an orbital resonance between Jupiter and Mercury could perturb Mercury's orbit enough to get it to collide with Venus is inconsistent with Ovenden's conjecture. It's matter of conflicting computer models, so nothing to get excited about.

It says nothing about whether or not they could contrive to say eject Mars from the solar system entirely. What is known from composition of the planets is that they didn't all form exactly where they are now.

The currently favoured hypothesis about how Earth got it's Moon does depend on that.
--
Bill Sloman, Sydney