Our Janet Jackson Vintage Pop Stardom Week continues in 1998, with a post-'Janet.' Janet feeling two ways about her pop stardom and looking to try something a little different. Janet Jackson performs at Flanders Expo in Gent, Belgium on April 19th, 1998. Gie Knaeps/Getty Images Trending on Billboard In honor of her upcoming 60th birthday this Saturday (May 16), we’re doing  a full week  of  Vintage Pop Stardom  deep dives into the all-time greatness of  Janet Jackson  on the  Greatest Pop Stars  podcast.  Each day this week (May 11-15), we’ll look at a different peak year in Janet Jackson’s singular career —  1986 , 1990 , 1993 , 1998 and 2001 — and hit on all the albums, singles, videos, dance routines, tours, performances, fashion statements, social and political statements, and other big moments that made Ms. Jackson’s contributions to the music and culture of those years absolutely unforgettable.…