P5 2 A Rayleigh Good Time How Different Stars Paint Alien Skies

Abstract

We investigate the colour of a clear sky under main-sequence stars of different classifications.
A previous paper, ’Mr. Blue Sky’, outlined a method which associated the sky colour with a
single, peak wavelength. Ward et al. [2] predict a green sky for an unscattered spectrum, and
an ultraviolet sky for a scattered spectrum. Instead, we use the scattered blackbody spectrum to
calculate chromaticity, finding blue skies for A0–M0 stars and a white sky near 3300 K. We find
that the chromaticity coordinates for the Earth’s sky are x = 0.236±0.003 and y = 0.237±0.004,
which suggests our method predicts a bluer sky than observed.