P5 3 "Until the Sky Turns Green"

Abstract

In the popular Stone Roses song, Sugar Spun Sweetheart, there is a lyric “Until the sky turns
green, and the grass is several shades of blue”. In this paper we will be examining whether
it would be possible to witness a green sky, firstly, by discussing whether particles exhibiting
Rayleigh scattering can cause a green sky instead of blue, and secondly, what speeds a person
would need to travel to redshift the sky’s natural blue colour to green. We find that there are
no conditions under which Rayleigh scattering can produce a green sky, however if an observer
accelerates to an approximate speed of 0.2c, then they will observe a green sky, due to the Doppler
effect.