Mar 7, 2021 Swiss physicist and Nobel laureate Charles Guillaume said of him, “There are, in fact, two satellites orbiting the Earth. One we call the moon, and the other is the eminent Dr. Tanakadate.” Yet despite such extraordinary praise, Aikitsu Tanakadate, the father of Japanese seismology and Japanese aviation, is pitifully unknown both in his own country and around the world. When last month, on the night of Feb. 13, the Tohoku region was struck by a magnitude 7.3 earthquake, an aftershock of the Great East Japan Earthquake 10 years ago, I thought of Tanakadate. This massive aftershock was most strongly felt in the town of Ninohe, Iwate Prefecture — Tanakadate’s birthplace, which I visited a few years ago to learn more about the man who was arguably Japan’s greatest modern scientist.