The astronomical world has lost one of its brightest stars, as Dr. Brian G. Marsden passed away yesterday morning.
Brian made a significant contribution to our understanding of the motion of comets during the last 40 years. He successfully modeled the nongravitational forces that affect the orbits of comets. These forces are a result of the jet-like action of ice and dust shooting into space like a geyser as comets near the sun. Brian found that these forces can slightly speed up or slow down some comets. The result of his modeling enabled the perihelion dates (the moment when comets are closest to the sun) of several short-period comets to be predicted to within an hour or less, instead of several days. This not only led to fewer comets being lost, but many older lost comets were subsequently found as a result of Marsden’s work.
Perhaps an even greater contribution was that he was a champion for the amateur astronomer. The internet discussion lists involving comets and minor planets were alive yesterday with remembrances of Brian’s assistance and encouragement. Several professional astronomers noted that it was Brian’s enthusiasm and encouragement during their years as an amateur astronomer that inspired them to pursue their professional careers. Several amateur astronomers pointed out that Brian was always quick to provide answers to their questions, as well as suggestions on how to improve their contribution. The result is that amateurs make important contributions to the science of astronomy, which is not always the case in most other sciences.
On a personal note, I owe a lot to Brian Marsden. We began corresponding by mail in the mid-1970s. He quickly learned that I was a journalism student, with a passion for observing, researching, and writing about comets. My first book on comets was published in 1984, but my dream was to write a multi-volume history on comets. Brian was always encouraging, quick to answer questions, and helped to point me in the right direction during my research. If I called him on the telephone, he always answered and always seemed to have plenty of time to talk, even though I knew he was probably busy. As my research expanded in the early 1990s, Brian offered to read samples of what I had written, paying me both compliments and offering constructive criticism. Imagine my surprise when I received an e-mail from Cambridge University Press in 1995 which expressed an interest in my project. As it turned out, Brian had talked to an editor about my project and had convinced him of its value. I was quickly signed to a contract and the sixth and final volume of Cometography is due out next year.
Parents are usually the prime motivators in a person’s life, as mine certainly were. But my astronomical endeavors were certainly shaped by Brian. I consider him a mentor. As a result of all my work in compiling comet history, the International Astronomical Union named minor planet 48300 after me in 2003. Every time I manage to obtain an image of minor planet “Kronk” from my observatory, I know that this would not have happened without the help of Brian.
Brian died as a result of contracting pneumonia while battling leukemia for the past year. He was 73 years old.