Longtime Boston DJ George Knight is going back to school. Knight, well known in radio circles for a his stints at WKLB-FM (102.5), WMJX-FM (106.7), and WBOS-FM (92.9), has taken a job with the Emerson College station WERS-FM (88.9). Knight is joining the student-run station as cohost of its morning show, becoming WERS’s first professional on-air staff member. “I’m excited to cohost the morning show alongside students, and to have the chance to share some of the wisdom I’ve picked up over my 20 years on Boston radio,” Knight said in a statement. “My guess is the students will have a thing or two to teach me, too.” Most recently, Knight hosted an evening show at WUMB-FM (91.9), an NPR affiliate at UMass-Boston.