36th DPS Meeting, 8-12 November 2004
Session 42 Extrasolar Planets
Oral, Friday, November 12, 2004, 8:30-10:00am, Clark

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[42.09] Specular Reflection of Starlight off Distant Planetary Oceans

D.M. Williams (Penn State Erie, The Behrend College), E. Gaidos (U. Hawaii)

Once future TPF observatories begin to detect Earth-size planets, searches for signatues of habitable surface environments and life will begin. There are several possible indicators of water oceans: The spectroscopic detection of atmospheric water vapor would be an indirect indicator of stable water bodies on the surface. A deep, overturning ocean would produce a lag between the insolation and temperature cycles, which might be observable in the rotationally-averaged infrared light curve of a planet along its orbit (Gaidos and Williams 2004; New Astronomy).

Planets with transparent atmospheres will also exibit strong directional scattering of starlight from the relatively smooth surfaces of oceans. Here we simulate the specular reflection of starlight off the surface of Earth-like planets to calculate visible light curves for different viewing geometries, obliquities, and land-sea fractions. The amplitude and polarization of the reflected signal is found to be strongly dependent on the waviness and expanse of the ocean. Planets are naturally brightest in crescent phase when the oceans most-effectively scatter starlight in the direction of Earth.

The author(s) of this abstract have provided an email address for comments about the abstract: dmw145@psu.edu

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.