The Harvard-Smithsonian Center for Astrophysics will host a free Observatory Night and lecture on Thursday, May 16, at 7:30PM at Phillips Auditorium, 60 Garden Street, Cambridge. The topic: Giant black holes at the centers of galaxies — the most powerful engines in the universe. In active galaxies they blast out jets of material at near-light-speed, and when galaxies collide, their black holes merge with a dramatic burst of gravitational waves that can kick the black hole out of the galaxy entirely. Travel to the lairs of these hungry monsters and uncover their secrets. This Observatory Night talk will be followed by viewing through telescopes (weather permitting). Free and open to the public. For more information: pubaffairs@cfa.harvard.edu, 617-495-7461, More info: www.cfa.harvard.edu