Pioneering Women

Hisako Koyama Was The Amateur Female Astronomer Who's Earned Galileo Status

It's not every day an amateur rises to the level of history's greatest scientists, and it's even rarer for that amateur to be a non-European woman with just a high-school education. But that's the story of Hisako Koyama, a Japanese astronomer born in the early 20th century whose thousands of sunspot illustrations are being published right alongside greats like Galileo himself.

An Unlikely Life

Koyama was born in 1916 and graduated from a Tokyo high school in the 1930s, a rare feat for any child during that era. In pre-WWII Japan, women still didn't have the right to vote, and were encouraged to fulfill the saying "umeyo, fuyaseyo": have more babies and increase the population.

But Koyama had her sights set higher — much higher. She devoured astronomy books, including a reference guide on how to make telescopes. She even made her own telescope after being inspired by a trip to the Tonichi Planetarium in Tokyo, and soon got ahold of a store-bought refractor telescope as a gift from her ever-supportive father.

She used that very telescope to check out the sun. After a month of careful observation, she managed to sketch her first sunspots in 1944. That was a much easier challenge than what she did next: she gathered the courage to mail it to Professor Issei Yamamoto, the Solar section president of the Oriental Astronomical Association (OAA). Incredibly, she received a reply: "Thank you for your observation report," Yamamoto wrote. "Yes, they are sunspots." That bit of positive feedback was all Koyama needed to dive head-first into a life of astronomy.

Over the next two years, she began making regular observations of the sun at Tokyo's National Museum of Nature and Science, known then as the Tokyo Science Museum. She was hired as a staff observer there in  and continued to work for the museum until she retired in 1981. Over that time, she chronicled and published more than 8,000 sunspot groups, including the largest sunspot of the 20th century in 1947. All the while, she was a passionate science communicator who organized frequent special events and monthly seminars for the public. From the beginning of her career until her death in 1997, Koyama made more than 10,000 solar sketches.

Modern Discovery

Fast forward to modern day: a group of scientists is trying to figure out how many sunspots humanity has seen since the first observation in 1610. As they're rifling through 400 years of historical observations, they happen upon Koyama's work, and add her drawings to the others they had collected from the likes of Pierre Gassendi, Johann Caspar Staudacher, Heinrich Schwabe, Rudolf Wolf, and of course, Galileo Galilei.

"Those five names are the giants of sunspot records," said Delores Knipp, a space weather scientist at the University of Colorado Boulder and the lead author of a study about Koyama's work. "And her name comes right along with them. So clearly, her records are in a class of great historical scientific records."

That reconstruction of the sunspot record will help scientists better understand how the sun's magnetic activity changes over time and, accordingly, how that affects Earth. Koyama's sketches fill what may otherwise be a 40-year gap in that record. And to imagine, all she needed were kind words from a role model. "How many young 'Ms. Koyamas' might there be in today's world, just on the verge of scientific contribution and discovery," Knibb writes in the study, "if only for a nudge of encouragement in the right direction?"

To learn more about pioneering women, we recommend "Headstrong: 52 Women Who Changed Science-and the World." The audiobook is free with a trial of Audible, and your click helps support Curiosity.

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Written by Ashley Hamer October 20, 2017