Kiyotsugu HIRAYAMA and Seitaro SUZUKI : SUZUKI's Destruction Experiments in Laboratory with astronomical Interest

Abstract

Astronomer Kiyotsugu HIRAYAMA (1874-1943), known for his discovery of the families of asteroids in 1918, advocated the explosion theory that any families of asteroids were formed out of the breakup of a single large asteroid. Since, however, he had no decisive astronomical evidence for the theory, he asked experimental physicist Seitaro SUZUKI (1887-1977) to carry out experiments in SUZUKI's laboratory to obtain the data which support the theory. In response, SUZUKI conducted from 1931 1938 a series of experiments to destroy balls (made of sealing wax, clay and chalk) and investigated the relation between the sizes of fragments and their numbers by varying the impulse given to the balls. The destruction of balls was meant to be an analogue of the destruction he assumed of asteroids. Comparing experimental results obtained in the laboratory and the observed SIZE distribution of asteroids, he could only show that the explosion theory for the origin of the asteroids was a little more preferable to the alternative, collision theory. Both HIRAYAMA and SUZUKI had shared common interest in explaining astronomical facts by employing experimental results obtained in laboratories. However on the other hand, there was a small but significant difference in their focal points. Astronomer HIRAYAMA wanted to know specifically the origin of the families of asteroids, while physicist SUZUKI was interested in the origin of asteroids themselves in a broader perspective. In fact, SUZUKI had carried out in 1921, without any astronomical interest, some experiments he conducted in 1930s were motivated by his astronomical interest, they were an exteded version of those earlier experiments.