Detecting the glint of starlight on the oceans of distant planets

Darren M. Williams, Eric Gaidos

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

We propose that astronomers will be eventually be able to discriminate between extrasolar Earth-like planets with surface oceans and those without using the shape of phase light curves in the visible and near-IR spectrum. We model the visible light curves of planets having Earth-like surfaces, seasons, and optically-thin atmospheres with idealized diffuse-scattering clouds. We show that planets partially covered by water will appear measurably brighter near crescent phase (relative to Lambertian planets) because of the efficient specular reflection ("glint") of starlight incident on their surfaces at a highly oblique angle. Planets on orbits within 30° of edge-on orientation (50% of all planets) will show pronounced glint over a sizeable range of orbital longitudes, from quadrature to crescent, all outside the glare of their parent stars. Also, water-covered planets will appear darker than a Lambertian disk near full illumination. Finally, we show that planets with a mixed land/water surface will polarize the reflected signal by as much as 30-70%. These results suggest several new ways of directly identifying water on distant planets.

Original languageEnglish (US)
Pages (from-to)927-937
Number of pages11
JournalIcarus
Volume195
Issue number2
DOIs
StatePublished - Jun 1 2008

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glint
planets
oceans
planet
ocean
light curve
water
glare
ocean surface
specular reflection
Earth surface
surface water
quadratures
illumination
sea surface
orbits
scattering
atmospheres
stars
orbitals

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Williams, Darren M. ; Gaidos, Eric. / Detecting the glint of starlight on the oceans of distant planets. In: Icarus. 2008 ; Vol. 195, No. 2. pp. 927-937.
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Detecting the glint of starlight on the oceans of distant planets. / Williams, Darren M.; Gaidos, Eric.

In: Icarus, Vol. 195, No. 2, 01.06.2008, p. 927-937.

Research output: Contribution to journalArticle

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AU - Gaidos, Eric

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