Reply to post: Re: More than a coincidence?

ALIENS are surely AMONG US: Average star has TWO potentially Earth-like worlds

Nigel 11

Re: More than a coincidence?

The orbit of any planet in a solar system with more than one planet is chaotic. (Mathematical fact, mathematical definition of chaotic). Given infinite time, all but one planet will inevitably be ejected into interstellar space (or less likely swallowed by its sun or collided with another planet).

Fortunately for us, "enough time" for our solar system greatly exceeds the lifetime of Sol. Also the future orbit of Earth can be predicted to remain much as it is today for the next 100My at least, given the accuracy of the best astronomical observations of the rest of the planets in our system and inverse-squares gravitation.

However, in a solar system with a Jupiter-mass planet in a very eccentric orbit, smaller planets would not remain in the Goldilocks zone for the (assumed) billions of years it takes for advanced life to evolve.

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