Seb Falk Receives 2025 Osterbrock Book Prize

The prize committee of the Historical Astronomy Division (HAD) of the American Astronomical Society is pleased to announce that the winner of the Donald E. Osterbrock Book Award for 2025 will be Seb Falk for his book The Light Ages: The Surprising Story of Medieval Science, published in the US by W. W. Norton in 2020.

This exceptionally well-written book begins with a mystery that arose in 1951 with the discovery of a manuscript dated 1392, written in Middle English, not Latin, and appearing to be the work of Geoffrey Chaucer. In 2014 a Norwegian scholar identified the author as John Westwyk, a Benedictine monk who lived in the second half of the fourteenth century. The Light Ages tells the story of how astronomical knowledge was applied and used during this era through the eyes of this monk, whose work has not been covered by other writers. The narrative involves a description of one famous clock that gave the phases of the Moon, told solar time, and tracked the tides at London Bridge, along with devices like John Westwyck’s six-foot-diameter analog calculator. Seb Falk’s book is based on his laborious scholarly research but reads like a pleasurable detective story.

Seb Falk is a historian, teacher, broadcaster, and historical consultant. He teaches medieval history and history of science at Cambridge University, where he is a Fellow of Girton College. Seb received his BA in History and Spanish from Oxford University, and an MPhil in History and Philosophy of Science from Cambridge. He stayed at Cambridge for a PhD, completing his thesis on late medieval astronomical instruments in 2016. He specializes in the history of astronomy, navigation, and mathematics — theories and technologies — from their ancient origins to modern developments.

The Donald E. Osterbrock Book Prize is given in odd-numbered years. Books copyrighted in the two to five years before the award year are eligible. HAD originated the prize in 2009 and named it in memory of Donald Osterbrock in 2010. Osterbrock was a longtime HAD member, a contributor to nearly every HAD meeting, HAD Chair from 1987 to 1989, and the recipient of HAD’s highest honor, the LeRoy E. Doggett Prize for Historical Astronomy, in 2002. He was also the author of several books and articles on the history of astronomy.

The 2025 Osterbrock Book Prize will be presented to Dr. Falk in Anchorage, Alaska, in June 2025 at the 246th AAS meeting.

We would like to thank the members of the HAD Prize Committee for their efforts in selecting this year’s award winner: Marcia Bartusiak, Sethanne Howard, Susana Deustua, Terry Oswalt, and Kevin Krisciunas (Prize Committee Chair).