2006/10/17 by P. R. McCullough, McCullough, P. R.
Agricultural and Biological Sciences · Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #Cephalopods and Marine Biology #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0610518
18 pages, 12 figures, as submitted to ApJ
arxiv created 2006/10/17 · openalex publication_date 2006/10/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Specularly reflected light, or glint, from an ocean surface may provide a useful observational tool for studying extrasolar terrestrial planets. Detection of sea-surface glints would differentiate ocean-bearing terrestrial planets, i.e. those similar to Earth, from other terrestrial extrasolar planets. The brightness and degree of polarization of both sea-surface glints and atmospheric Rayleigh scattering are strong functions of the phase angle of the extrasolar planet. We modify analytic expressions for the bi-directional reflectances previously validated by satellite imagery of the Earth to account for the fractional linear polarization of sea-surface reflections and of Rayleigh scattering in the atmosphere. We compare our models with Earth's total visual light and degree of linear polarization as observed in the ashen light of the Moon, or Earthshine. We predict the spatially-integrated reflected light and its degree of polarization as functions of the diurnal cycle and orbital phase of Earth and Earth-like planets of various imagined types. The difference in polarized reflectances of Earth-like planets may increase greatly the detectability of such planets in the glare of their host star. Finally, sea-surface glints potentially may provide a practical means to map the boundaries between oceans and continents on extrasolar planets.