Alien Maps of an Ocean-Bearing World

Details Alien Maps of an Ocean-Bearing World Alien Maps of an Ocean-Bearing World

2009-05-22

arxiv.org/abs/0905.3742v1

Astrophys.J.700:915-923,2009

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

11 pages, 15 figures, accepted for publication in ApJ

Scientific paper

10.1088/0004-637X/700/2/915

[Abridged] To simulate the kinds of observations that will eventually be obtained for exoplanets, the Deep Impact spacecraft obtained light curves of Earth at seven wavebands spanning 300-1000 nm as part of the EPOXI mission of opportunity. In this paper we analyze disc-integrated light curves, treating Earth as if it were an exoplanet, to determine if we can detect the presence of oceans and continents. We present two observations each spanning one day, taken at gibbous phases. The rotation of the planet leads to diurnal albedo variations of 15-30%, with the largest relative changes occuring at the reddest wavelengths. To characterize these variations in an unbiased manner we carry out a principal component analysis of the multi-band light curves; this analysis reveals that 98% of the diurnal color changes of Earth are due to only 2 dominant eigencolors. We use the time-variations of these two eigencolors to construct longitudinal maps of the Earth, treating it as a non-uniform Lambert sphere. We find that the spectral and spatial distributions of the eigencolors correspond to cloud-free continents and oceans; this despite the fact that our observations were taken on days with typical cloud cover. We also find that the near-infrared wavebands are particularly useful in distinguishing between land and water. Based on this experiment we conclude that it should be possible to infer the existence of water oceans on exoplanets with time-resolved broadband observations taken by a large space-based coronagraphic telescope.

Affiliated with

Also associated with

No associations

Rating

Alien Maps of an Ocean-Bearing World does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Alien Maps of an Ocean-Bearing World, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alien Maps of an Ocean-Bearing World will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-498811