[ExI] kepler study says 8.8e9 earthlike planets

[Kelly Anderson]

On Thu, Nov 7, 2013 at 2:17 PM, spike <spike66 at att.net> wrote:

> >... On Behalf Of BillK
> Subject: Re: [ExI] kepler study says 8.8e9 earthlike planets
>
> On Thu, Nov 7, 2013 at 3:53 PM, spike wrote:
>
> >>...  Problem: the NASA  findings increased by four orders of magnitude
> the
> number of expected...
>
> >...You've even got Bloomberg worrying about it now!
>
> BillK, not I have got.  NASA's got.  I didn't do the study or write the
> report.
>
> <
> http://www.bloomberg.com/news/2013-11-06/don-t-believe-in-aliens-maybe-you-
> re-the-crazy-one.html>
> Quote:
> >...Fermi's question remains unanswered. But it only grows more compelling,
> and more perplexing, with each new discovery.  BillK
>
> _______________________________________________
>
> So before this NASA study came out, did you have an estimate of the number
> of Goldilocks planets?  I did: my ROM estimated was about a million or so,
> just by saying perhaps there is some reason why a Goldie needs a main
> sequence population 1 yellow dwarf with spectral type G2, old enough to
> have
> planets congealed out of a dust lane.  Then I estimated a typical
> Goldilocks
> band and came up with about a million such Goldies in the galaxy.
>
> So those who remember, did you have numbers in that OOM?  Who had one
> greater than ten billion?  What was your reasoning?  Who had one more than
> an order below a million?  Reasoning?
>
> In retrospect, I may have been letting Fermi influence my estimate
> downward,
> because I may have unconsciously been trying for an explanation of the
> silence based on the (probably absurd) notion that there just weren't
> enough
> decent planets out there.
>

The "earth like" definition used by the scientists that wrote the paper
include approximately three variables. Rare Earth proposes around 12 such
variables if I remember correctly.

For example, we need a molten core and plate tectonics in order to get the
right metals to the surface, provide both land and ocean (for the evolution
of land animals, since hands evolving on a fish seems like a bit of a long
shot) and other reasons.

Then there is Jupiter and Saturn filtering out the comets. Very useful that.

If you refigure all of the Rare Earth variables in with NASA's numbers, I'm
guessing you would end up with a MUCH smaller number.

-Kelly
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