Physics can be as basic as gravity and light, as strange as Einstein's theory of relativity, as other-worldly as Hilbert space, and as elusive as quarks. It is the study of the properties, transformations, and interactions of matter and energy--the search for unifying principles to explain the diverse phenomena of nature. Astronomy, with which physics is closely allied, can have equal appeal. The science of the stars and other heavenly bodies deals with such enigmas as pulsars, quasars, neutron stars, and black holes, as well as planetary motion and the composition and evolution of stars.