Saturday, September 10, 2022

Marginal Earths

I've got a couple posts here about whether we really are that lucky. First up was that Goldilocks thing: if we'd be better off closer to a more auburn (i.e. K) sun. Lately Eccentricity, where the Jupiter analogue is closer too or else maybe just bigger, but either way eccentric, thus pulling the inner planet to an eccentric orbit too.

Eccentricity can lead to yeeting. In a longer-lasting system (like a K system), the inhabitants can wait that bit longer; their sun might not catch up with them until the dynamo runs out. I am here for the shorter-lasting system. It has taken our Sun 4,567 million years to develop us - which span would rule out an F system. Some of this delay came from various physical setbacks; the worst delay may be an accident of plate-tectonics which just... did nothing.

An F system might luck out, if it escapes a Boring Billion (and, incidentally, also boils off the nearest comets). This can be extended to G systems with close-in heavy planets; they might eccentre the planet's orbit too far, but not too late for life to emerge.

I am unsure that eccentricity will help a K-system Earthlike however. It might exacerbate the infrared warming.

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