WHEN YOU LOOK AT THE image above, what do you think of? Most will probably take in the beauty of its subjects, the mountain Denali and nearby Wonder Lake. A photographer might admire the skill of its creator, Ansel Adams. Adventurers may feel the urge to climb.
Donald Olson sees all that and something else: a mystery. He wants to know the moment it was taken. An astrophysicist and forensic astronomer, Olson uses quantitative methods to answer questions raised by artwork, literature, and historical accounts—not the heady ones, but the basic, surprisingly slippery who, what, when, and where.