Since Sun Ra’s death in 1993 and that of his partner-in-crime John Gilmore last year, the leadership of Sun Ra’s Arkestra has passed to group lifer Marshall Allen. But Allen has at least 100 albums and over 40 years of challenging music to keep the Arkestra from slipping into mere repertory status. Ra’s musical styles are as numerous as the available selections, with the group confidently performing everything from big-band swing to intergalactic free music. Toward the end of his life, Ra’s illness forced him to sit on stage, hardly playing his keyboards, merely monitoring the proceedings like a king watching his court. Now that he has returned home—to Saturn, of course—his cosmic throne no doubt provides a much better view than the stage. At 8 & 10 p.m. at Underground Railroad, 2801 8th St. NE. $15. (202) 271-4410.CP