On 25 Feb 2016 at 16:23, Phil Pugliese (via tml list) wrote:

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>  Stars of low enough mass that they'll not go supernova and  likely
>  stay on the main sequence long enough for life to evolve will become
>  red giants after they run out of hydrogen in the core.
>
>  That's not the sort of star "death" we see (mostly because it takes
>  longer than we've had astronomy).
>
>  And the star expanding is more likely to boil off volatiles than
>  freeze a formerly habitable planet.
>  --
>  Leonard Erickson (aka shadow)
>  shadow at shadowgard dot com
>
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>
> Using our solar system as an example, could you speculate on what would happen when our sun expands into a 'red giant'?

> p.s. I recall reading, a loooong time ago, that the chromosphere could actually expand out beyond the orbit of the Earth, or maybe even Mars!

It's been gone over in lots of places. But even if it doesn't expand
out all the eway to Earth, we won't be in the "habitable zone"
anymore.

It'll happen slowly, but likely not slowly enough for life to evolve
on newly warmed planets or life to adapt on ones that already have
it.

As I recall we are talking about  time scales that are only a few
million years.

At least intelligent life (if it has develpoed space travel) can move
farther out.

And eventually the red giant phase ends and the sun will
(peacefiully?) become a white dwarf.

http://www.astro.cornell.edu/academics/courses/astro201/evol_sun.htm
http://www.whillyard.com/science-pages/our-solar-system/sun-evolution.html

I see that Earth will be pretty much uninhabitable *before* the sun
gets to the red giant stage...

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com