Halley's Comet, starring John Amos, is being performed at the Germantown Performing Arts Center. Hair opens at Playhouse on the Square, and Our Own Voice Theatre Troupe's productionof Ecstatic Disco Nights or Tingles Hot Lover opens at Theater Works. Tonight's art openings are at: David Mah Studio, for "Life Goes On....The Complimentary Tangents of Tomy and Jerry" by Tommy Marva; Silver Salon and Day Spa, for works by Cornelius Carter, Jonathan Segerson, and Anthony James, Perry Nicole Fine Art, for "A Still Moment," works by John Van Dreal and Lesie Staub; and David Lusk Gallery, for photography by Jack Spencer and sculpture by Brian Russell. If you want to see some of Ballet Memphis' dancers close up before their first program of the season, you can see them rehearse tonight at the company's studios during Fr9day Night in the Studio with Ballet Memphis. Down in Tunica, T.G. Sheppard is at Bally's; Teddy Pendergrass is at the Horseshoe Casino; Gerald Levert is at Sam's Town, and The are at Gold Strike. Here at home, Christian Yeager is at the full Moon Club upstairs form Zinnie's East, and Emmy-winning folk singer/guitarist Geoff Muldaur -- fresh from stints at Carnegie Hall, the Kennedy Center, and the Newport Folks Festival -- is playing tonight at Otherlands Coffee Bar, guest of the Memphis Acoustic Music Association.