Because it's hard to look directly into the sun. Or yourself.

See the image:
http://www.thelonelypalette.com/episodes/2017/5/22/episode-18-jmw-turners-the-slave-ship-1840

Music used:
The Andrews Sisters, "Bei Mir Bist Du Schoen"
The Blue Dot Sessions, "Sunday Lights", "Town Market", "Rapids", "Liptis", "Ballast", "Masonry"
Joe Dassin, “Les Champs-Elysees”