Not long ago, the definition of a circus—the touring show arriving annually at a sports arena near you—was fairly narrow and stale. But recently the tradition’s gotten a boost, expanding in two directions. At one end, circuses got smaller, scruffier, and simultaneously alt- and retro-, merging with burlesque (the Jim Rose Sideshow, Circus Contraption, etc.). At the other, they got bigger, glossier, more special-effecty, and more “sophisticated,” in a style that might be dubbed Eurovegas (with Cirque de Soleil leading the pack). Polishing itself up while remaining purely family-friendly, Ringling Bros. and Barnum & Bailey® has mixed a lot of magic into the standard animal/clown/acrobat recipe for its current show, Zing Zang Zoom. It promises a disappearing elephant, Bengal tigers, and the “quadruple Russian fire-swing,” among much more. And as with any self-respecting circus these days, a mere string of unrelated acts isn’t enough—there’s a through-story, as the performers battle “a cynical Mr. Gravity and his team of Heavies who try to bring everyone down.” (Through Labor Day at Kent’s ShoWare Center; then moves to Everett’s Comcast Arena, Sept. 10-13.) GAVIN BORCHERT

Aug. 3-Sept. 7, 7:30 p.m.; Sept. 10-13, 2009