An exhibition of astronomical maps and illustrations opened this week at the Osher Map Library in Portland, Maine. Art of the Spheres: Picturing the Cosmos since 1600 is, at least in its online version, divided into two categories: Works of Scientific Investigation features chromolithographs of various astronomical phenomena, the moon, planets and deep sky objects from The Trouvelot Astronomical Drawings (1881); Popular and Pedagogic Works includes celestial globes, charts and other graphical representations of the universe. Runs until 6 October.