Hisako Koyama was an astronomer who produced one of the most influential sunspot collections of the past 400 years.
Born in Tokyo in 1916, Koyama grew up in a society that didn’t encourage young women to pursue careers. Koyama graduated from an all-girls high school in the 1930s, which was rare for girls of her time.
From a young age, Koyama was fixated on the sky, and her father nurtured her growing enthusiasm. He bought her a telescope, and by 1944, Koyama directed that telescope toward the sun.
Sunspots temporarily appear when there’s high magnetic activity in a concentrated area on the sun’s surface. The temperature in those places are cooler, and the spots produce less light than the rest of the surface. The sun goes through an 11-year solar cycle, and sunspot numbers fluctuate at the cycle’s end. Scientists track sunspots because they predicate solar activity like solar flares–which can mess with satellite communications around the Earth.
Koyama hand drew sunspots every day. When her renderings are joined, it’s like watching the spots move as the sun rotates each day.
Koyama watched images like this for more than 40 years. She pulled together her life’s work, about 10,000 sunspot drawings from 1947 to 1984, and published them in her book called “Observations of Sunspots.”
Koyama is considered a pioneer of Japanese citizen science and has been a messenger between the professional and amateur astronomy spheres. Today, astronomers from across the globe are learning from her work and hope her story can inspire young women everywhere to pursue their passions.
Photos: Asahigraph, Kawade Shobo Shinsha Publishers, NASA/SDO, National Museum of Nature and Science in Tokyo
