“Strange as it may seem, 96 percent of the universe seems to be made of two ingredients that no one understands.” This shining addition to the Scientists in the Field series focuses on astronomer Alex Filippenko, part of a team researching dark energy and dark matter in the universe. Jackson’s clear, logically organized text provides appropriate background, introducing Filippenko as teacher and researcher and following him as he uses the Keck Observatory in Hawaii to find a supernova. One chapter discusses current thinking about the big bang theory and the composition of the universe, and the book concludes with a description of the scientist’s day-to-day work at the Lick Observatory in California. Bishop’s photographs and illustrations bring readers into Filippenko’s world, while NASA photographs add to their sense of wonder. Special sections explain spectrographs, the electromagnetic spectrum, black holes and the measurement of time and light. Thoughtful design adds to the pleasure of this splendid invitation to explore darker corners of the universe. (bibliography, student and teacher resources, clubs and organizations, glossary, index) (Nonfiction. 10 & up)