In one of my more obsessive moments I once dragged my reluctant friend John to a Sun Ra performance. I say “obsessive” because I knew John wasn’t particularly musically inclined, much less interested in outside jazz. Ra’s show that night was typical; he conducted some 15 musicians dressed like extras from an old Flash Gordon serial through a set in which he presented his own highly personal take on the history of jazz, ranging from old numbers by Fletcher Henderson (Ra’s mentor) to peerless examples of “free” collective improvisation, finally spiraling down to pianist Ra banging out hard and funky blues against a sparse three-chord bass/drums pulse with the rest of the Arkestra grooving it up on scrapers and rattles. By the time Ra moved upstage to lead the band through swinging impromptu call-and-response chants (“We travel the space-waays / From planet to plan-et”), I expected to see John fidget, but he was grinning, and at intermission he simply turned to me and said, “Thank you for coercing me.” Which goes to demonstrate, I guess, that a Sun Ra show is a show for just about everyone. Saturday, Cubby Bear, 1059 W. Addison; 327-1662 or 477-7469.