Sky & Telescope - March 2025 - 28

ASTRO BIO by Klaus R. Brasch
Bart and Priscilla Bok:
A Galactic Love Story
Two astronomers shared a connection with the stars that was both
personal and professional.
L
ate last summer, while getting ready for a night of
observing from my backyard patio in Flagstaff, Arizona,
I heard a voice asking, " Is that a telescope? " I
had caught the attention of two ladies on an evening stroll.
" Yes, " I replied, " do you have one too? " " No, " the elder
lady said, " but my father was a famous astronomer. " To
my surprise and delight, one of my visitors was Joyce Bok
Ambruster, the daughter of Bart Bok and Priscilla Bok! It
turns out that she, along with the Boks' granddaughter,
Jeanne Bok Ambruster, and their great-granddaughter, Jane
Fairfield Becher, also live in town. The stars must have been
favorably aligned that warm summer night, as it marked
the 40th anniversary of Bart's passing on August 5, 1983.
Clearly my encounter with his family was predestined. I
arranged to interview them so that I could write this article
about their famed relatives.
At Home in the Milky Way
Most readers of this magazine are familiar with the Boks.
Few 20th-century astronomers contributed as much to
unraveling the mysteries of the Milky Way than Bartholomeus
Jan " Bart " Bok and Priscilla Bok. The couple
focused on the Milky Way's origin, evolution, and composition.
In doing so they followed in the footsteps of William
Herschel, who first attempted to map and model the
galaxy visually in 1785, and E. E. Barnard and Max Wolf,
who pioneered wide-field Milky Way photography at the
turn of the 20th century. As the couple wrote in the opening
pages of their immensely popular book, The Milky Way,
" . . . we invite you to join us on a brief tour along the road
to the heaven of the Greeks. Modern science has provided
the transportation facilities and, without its being necessary
for you to leave your comfortable chair, we would like
to show you the sights. "
Little did they realize when their book first appeared in
1941 that the tour they described was only the beginning of
a remarkable journey that would change our understanding
not just of our home galaxy but of the realm of galaxies
beyond. Exactly 40 years later, Bart Bok, now a widower,
poignantly dedicated the fifth and final edition of The Milky
Way this way: " To Priscilla with my love. This is the first
time I have revised the book without her. . . . "
Bart Bok, along with Gerard Kuiper, Jan Oort, and Pieter
Oosterhoff, were among a cohort of distinguished Dutchborn
scientists who contributed to virtually every aspect
of observational astronomy in the early 20th century. Bok
globules, the Kuiper Belt, and the Oort Cloud are testaments
to the recognition these astronomers eventually
attained. Bok and Kuiper later became U.S. citizens and
joined the University of Arizona, where Kuiper headed the
newly established Lunar and Planetary Laboratory, and Bok
led the university's Department of Astronomy and became
director of its Steward Observatory.
pMAGNIFICENT GALAXY This view of our home galaxy conveys
some of the grandeur that inspired Bart and Priscilla Bok to write
The Milky Way, one of the most popular books on astronomy in the
1940s and '50s.
DYNAMIC DUO Bart and Priscilla Bok are portrayed in this undated
family photo. When the two met in 1928, Priscilla was already an
established astronomer while Bart was still a graduate student at the
University of Groningen in the Netherlands.
28 MARCH 2025 * SKY & TELESCOPE
MILKY WAY: ALAN DYER; BART AND PRISCILLA BOK: BEATRIZ
INGLESSIS BASED ON A PHOTO BY JEANNE BOK AMBRUSTER
Sky & Telescope - March 2025

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