Re: life test for planets

From: Doug Jones (
Date: Sat Jan 26 2002 - 17:47:49 MST wrote:
> <<Planet reveals telltale signature of plant life
> Astronomers have identified a telltale signature of plant life in
> light reflected from a planet for the first time - but the planet is
> Earth. Researchers at the Haute Provence Observatory in France
> collected light from Earth that had bounced back down from the
> shadowed side of the Moon.
> "It's curious that no-one thought of doing this before," says Jean
> Schneider, of the Paris Observatory, who helped interpret the data.
> The signature of plants in the light is clear, he says: "There is a
> lack of reflection below 725 nanometres."

Curious but quite possibly pointless- that chlorophyll is the dominant
photosynthetic compound on the surface of the earth today is an accident
of history. If the green slime hadn't poisoned the atmosphere two
billion years ago, rhodopsin would be *the* signature of a living
planet. To expect that independently evolved life in another solar
system would use the exact same chemical pathways as on earth is
provincial thinking in the extreme.

Doug Jones, Rocket Plumber
XCOR Aerospace

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