In honor of her 60th birthday, May 11 will start a week of Vintage Pop Stardom deep dive looks into five of the all-time pop star's greatest years. Close-up of American singer and actress Janet Jackson on the set of her film 'Poetic Justice' (directed by John Singleton), 1993. Anthony Barboza/Getty Images Trending on Billboard Few, if any, pop stars throughout history have had a more incredible run than Janet Jackson at her peak. From 1986 to 2001, she released five full-length albums — each of which topped the Billboard 200, each of which generated at least one No. 1 hit on the Billboard Hot 100, each of which helped to define their era in pop, R&B and culture in general, and each of which proved enormously impactful on pop stardom, both in real time and for generations to come. And perhaps most impressively: Each of those album eras felt completely separate from the ones before or after, reframing Jackson’s artistry and shaping her legacy in a totally new way.…