Somewhere, over the rainbow, far far away
November 7, 2012 2:49 AM Subscribe
The light from a primary rainbow is partially polarised. Now, in a paper accepted by the journal Astronomy and Astrophysics, the authors show how to use the weak signal from rainbows in starlight reflected by exoplanets to detect the presence of liquid water clouds. [arXiv preprint link]
In particular, liquid water clouds covering as little as 10%-20% of the planetary surface, with more than half of these covered by ice clouds, still create a polarized rainbow feature in the planetary signal. Indeed, calculations of flux and polarization signals of an exoplanet with a realistic Earth-like cloud coverage, show a strong polarized rainbow feature.
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