David Bowie contributed a huge amount to popular culture, fashion and especially his music. His musical references to space travel and the planets are legendary including Life on mars, Ziggy Stardust  and the spiders from Mars, Starman and a Space oddity etc. (just like this new planet). Therefore, who better to name the new planet after, than the man who inspired millions of people and gave us decades of dreaming of other worlds, planets and stars.