Astrophysicist, mapper of the universe, and educator employed at the Harvard-Smithsonian Center for Astrophysics since 1974. In 1983, she became a permanent staff member of the Smithsonian Astrophysical Observatory, and in 1988, she became a professor of astronomy at Harvard. In 1989, Geller and her collaborator 'John Huchra' discovered the "Great Wall," an enormous arc of galaxies that is one of the largest known structures in the universe.