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Fraser
2012-Feb-29, 07:10 PM
Earthshine – a poetic, fanciful word for the soft, faint glow on the Moon when the light from the Sun is reflected from the Earth’s surface, onto the dark part of the Moon. And as unlikely as it might seem, astronomers have used Earthshine to verify there’s life in the Universe: Us. While we already [...]

More... (http://www.universetoday.com/93880/life-in-the-universe-reflected-by-the-moon/)

Selfsim
2012-Mar-01, 12:20 AM
With great respect for UT, I find this article somewhat misleading, when compared with the research actually presented in the linked paper. (My underlines):

While we already know about life on our own world, this technique validates that faint light from distant worlds could also be used to find potential alien life.The only way spectropolarimetry could be validated as a method for detecting any life, (in Sterzik's own words (http://www.eso.org/public/archives/releases/sciencepapers/eso1210/eso1210.pdf) … and only as far as Earth's model goes), is through:

Improved vector radiative transfer models with more realistic cloud and surface treatment are necessary to fully account for the observed spectra. Validation of these models is necessary to interpret Earth-like exoplanet polarization spectra.
The models he is referencing, come from another study (by D. M Stam) (http://arxiv.org/pdf/0707.3905v1.pdf), and these were solely intended as only a way of characterising Earth-'like' extrasolar planets.

Reducing the search-space in the plethora of confirmed exo-planets, is a completely distinct part of an overall process of finally discovering 'alien life', and could quite easily lead nowhere. The only way to deduce 'alien life' from spectropolarimetry, is to correlate spectropolarimetric results with an instance of actually discovered 'alien-life'. Without such a discovery, we can only ever infer 'Earth-like alien life', and if the reflecting body is light years distant, then the only feasible way to add any 'weight' to such models, is to discover 'alien life' locally, (ie: within the confines of our physical 'exploration limitations), and then to validate its associated spectropolarimetric and radiative transfer models, (if present), against such a discovery.

Ie: overall, an enormous difference ... and logistically, enormously non-trivial !

Regards