Bart Bok

Bartholomeus Jan "Bart" Bok (April 28, 1906 – August 5, 1983) was a Dutch-American astronomer, teacher, and lecturer.

He is best known for his work on the structure and evolution of the Milky Way galaxy, and for the discovery of Bok globules, which are small, densely dark clouds of interstellar gas and dust that can be seen silhouetted against brighter backgrounds.

Bok suggested that these globules may be in the process of contracting, before forming into stars.

In 1928, he attended the International Astronomical Union (IAU) Third General Assembly in Leiden in the Netherlands.

Priscilla Fairfield was an associate professor in Astronomy, and the young Bart Bok was assigned to her reception committee.

He was a graduate student ten years her junior, but he fell in love and proposed to her at the end of the conference.

Priscilla did not accept his proposal at the time, and Bart corresponded with her for the next year before she finally agreed.

The following year, Bok broke off his thesis studies at Groningen with Piet van Rhijn and moved across the Atlantic to Cambridge, Massachusetts, on the invitation of Harlow Shapley, director of Harvard College Observatory, whom he had also met at the same IAU Assembly where he met Priscilla.

Bok married fellow astronomer Priscilla Fairfield in 1929, and for the remainder of their lives, the two collaborated so closely on their astronomical work that the Royal Astronomical Society said "from that point on it is difficult and pointless to separate his achievements from hers".

On September 9, 1929, two days after moving to the US, the two were married.

This caused some awkwardness with their mutual superior Shapley, who regarded Priscilla as something of a protégée and was protective of her.

While Bok had the greatest admiration for Shapley, it took Shapley time to build the required level of trust with Bok.

The Boks remained at Harvard University for almost thirty years, from 1929 until 1957, where he taught astronomy and directed the Harvard Observatory.

The Boks had two children: a son, John Fairfield, in 1930 and a daughter, Joyce Annetta (now Mrs John Ambruster), in 1933.

Priscilla stayed at home until the children finished high school, so she published less research herself in this period.

Nevertheless, she was consistently involved with supporting Bart's research and their public outreach activities often put them together and gave her some degree of recognition.

Bart was steadily promoted through the academic ranks: he completed his Doctoral dissertation entitled "A Study of the Eta Carinae Region" in 1932, became an assistant professor in 1933, an associate professor in 1939, associate director of the Harvard Observatory by 1946, and he became a full professor in 1947 when he was appointed to the Robert Wheeler Wilson Chair in Astronomy (some sources say this happened in 1945 ).

Meanwhile, Priscilla was also conducting her own research and writing with Bart, but she was not being paid, which prompted Bart to describe Shapley as "rather cheap when it came to hiring people".

The Boks displayed such great mutual enthusiasm for explaining astronomy to the public that The Boston Globe described them in 1936 as "salesmen of the Milky Way".

They worked together on research and co-authored academic papers, and their general interest book The Milky Way went through five editions and was "widely acclaimed as one of the most successful astronomical books ever published".

Bok's primary research interest was the structure of our galaxy.

When he was asked by the editors of Who's Who in America to submit a statement concerning "Thoughts on My Life", he wrote, "I have been a happy astronomer for the past sixty years, wandering through the highways and byways of our beautiful Milky Way."

Bart Bok was an exceedingly popular personality in the field of astronomy, noted for his affability and humor.

Their enthusiasm for explaining astronomy to the public led to them being well known: they were described as "salesmen of the Milky Way" by The Boston Globe in 1936.

The writing of this book, begun in 1937, was shared equally – according to Bart:

"Priscilla and I were working on the writing of the book on the Milky Way, and she had a little room upstairs where she did all her writing. We lived in Lexington at the time. The cleaning woman would say to her, "Upstairs you go, you've gotta go to work, don't just sit here and talk to me." And she worked very hard at it, and in the beginning we had eight chapters in the book. We agreed that I would write four chapters and she would write four chapters, and that we loved each other dearly, no problems. Then, after we had gone through this for about five or six months and the writing was getting under way we said, "Now, you take my chapters, I'll take yours, now we get a better homogeneous book." Well, Priscilla stood one day in front of the fireplace, saying, "If you want to change things that way, my part can go in the fireplace right now." She didn't do it. But that was really the most critical time that we ever had in our married life, trying to meld these two times four chapters into eight chapters.

But I think it worked out, and later on we did much better.

We had fun about it.

But I tell you, the writing of a joint book is not always easy, if you've got strong feelings about it."

When Bart became a naturalized US citizen in 1938, he shortened his first name to "Bart".

Their marriage began a close scientific collaboration that would span the next four decades, in which the Royal Astronomical Society said "it is difficult and pointless to separate his achievements from hers".

They co-authored a number of academic papers on star clusters, stellar magnitudes, and the structure of the Milky Way.

Bok was fiercely interested in the mechanical processes which form star clusters and galaxies, and his paper "The Apparent Clustering of External Galaxies" (Nature, vol. 133, p. 578) was the first to demonstrate how dissipation of a star cluster relates to its density, and so by examining the clusters in our galaxy he concluded that it cannot be older than about twenty billion years.

In the 1940s, Bok first observed small, dark clouds of dense cosmic dust and gas which would later become known as Bok globules in the Milky Way.

Their main work together was a definitive undergraduate textbook and popular science book, The Milky Way, "widely acclaimed as one of the most successful astronomical books ever published", which had five editions over forty years following its initial publication in 1941, and was translated into many languages.

In a paper published in 1947, Bok and E.F. Reilly hypothesized that these clouds were "similar to insect's cocoons" that were undergoing gravitational collapse to form new stars and star clusters.

When asteroid 1983 Bok was named for him and his wife Priscilla, he thanked the International Astronomical Union for giving him "a little plot of land that I can retire to and live on."

Bok was born in the small Dutch town of Hoorn, north of Amsterdam, to Jan Bok, who was a sergeant-major in the Dutch army, and Gesina Annetta (née van der Lee) Bok, but he spent a good deal of his childhood with his grandparents in the town of Haarlem, where he attended primary school.

He attended high school in The Hague, excelling at mathematics and science, and he also told the story that this was where he met a Scoutmaster who introduced him to the night sky while on camping trips away from the city lights.

After completing high school, he went on to study astronomy at Leiden and Groningen Universities.