The website Atlas Obscura has a rather interesting blog post about a virtually unknown Japanese amateur astronomer, Hisako Koyama (1916–??), who specialised in observing sunspots: How an Amateur Astronomer Became One of History’s Greatest Solar Observers.
I enjoyed reading this post until I stumbled across the following sentence:
Her daily observations of the Sun’s dark spots, drawn by hand, are one of the most rigorous and valuable records of solar activity ever made, and put her alongside Galileo as a careful, dedicated observer of celestial spheres.
Why the comparison with Galileo? He was indeed a careful and very perceptive observer but his dedication to observational astronomy can be seriously questioned. The contents of his Sidereus Nuncius were the result of observations undertaken from late 1609 until spring 1610. Having published his observations and having used that publication to obtain a cushy position as court mathematicus and philosophicus in Florence, Galileo’s interest in serious observational astronomy declined substantially. He was always prepared to demonstrate his telescopes to persons of influence but his further contributions to astronomical research were more than somewhat limited. He went into battle on several fronts, claiming priority for himself on the discovery of sunspots and the phases of Venus but these were not unique discoveries and his priority claims were at best dubious. He did spend some time trying to improve his observations of the orbits of the moons of Jupiter, in order to use them as a clock to determine longitude. However, he never completed this task, leaving it, so to speak, to Cassini to complete much later in the seventeenth century. By late 1613 he had effectively given up observational astronomy altogether. Here his dedication to the discipline is being used as a yardstick for a woman who devoted forty years of her life to observing the sun, couldn’t the author of the piece find a better famous astronomer for the comparison?
Staying in the Early Modern Period, but going back before the invention of the telescope, our first candidate could and should be William IV Landgrave of Hessen-Kassel (1532–1592).
In 1560 William establish the first modern observatory in Europe. With a varying team of astronomers, most notably Christoph Rothmann (between 1550 and 1560–probably 1600) and Jost Bürgi (1552–1632), he carried out an intensive programme of celestial observations until his death in 1592. This programme produced a highly accurate catalogue of almost four hundred star positions, as well as accurate determinations of the planetary orbits. One person who was much influenced by William pioneering work was our next candidate, Tycho Brahe. William who was related to the Danish king, Friedrich II, was instrumental in convincing his relative to finance Tycho’s observatory on the island of Hven. Tycho armed with financial resources others could only dream of and supported by a comparatively large force of assistants, who he trained himself, devoted almost thirty years to observational astronomy. He created a catalogued of over seven hundred star positions measured with an accuracy unknown before, as well as years worth of highly accurate observations of the planetary orbits; data from which Johannes Kepler would go on to determine that the planets orbit the sun on ellipses and not circles.
Moving on past Galileo we come to Giovanni Domenico Cassini (1625–1712) the real founder of telescopic astronomy, who devoted sixty-four years of his life to setting new standards of observational accuracy in astronomy, making many important discoveries along the way.
Cassini’s near contemporary Johannes Hevelius (1611–1687), a true amateur astronomer, devoted thirty-eight years of his life and a large part of the fortune he made as a beer brewer to an extensive programme of astronomical observations, producing amongst other things the most detailed and accurate map of the moon in the 17th century.
England’s first Astronomer Royal, John Flamsteed (1646–1719), carried out a forty-three year programme of observations at a level of accuracy several factors higher than his predecessors to produce a new star catalogue of 3000 star positions. Amongst his many other achievements, he was the first to suggest that a second comet observed in winter 1680 was in fact the first comet going back to whence it came having orbited the sun. This realisation led Newton to include the orbits of comets in his considerations of universal gravity and Halley to do the historical research that led to his determining the orbital period of the comet that bears his name.
Moving on into the eighteenth century we arrive at another great amateur, William Herschel (1738–1822) who, together with his sister Caroline (1750–1848) devoted nearly thirty years to the study of the heavens. As well as their famous discovery of the planet Uranus, they were pioneers in deep space astronomy, a discipline that would eventually lead to the discoveries of other galaxies beyond our own. Caroline would go on to make important astronomical discoveries of her own, as well as writing and editing the catalogues of deep space objects they had recorded.
All of the astronomers I have listed would make for better comparisons to the dedication of Hisako Koyama than Galileo and the first impression is that the author is just being lazy, “who’s an astronomer from history that everybody has heard of?” “Oh! I know Galileo, I’ll use him.” However it could be that she used him because Hisako Koyamma specialised in observing sunspots and Galileo was one of the first astronomers to observe sunspots with a telescope. He even got into a notorious dispute with the Jesuit astronomer Christoph Scheiner (1573–1650) over who first observed them and what they were. Galileo, rather shabbily, keep changing the date of his supposed first observation in order to claim priority.
All in vain as the first observations were made by Thomas Harriot (c. 1560–1621) and the first publication of sunspot observations was from Johannes Fabricius (1587–1616).
Galileo won the dispute with Scheiner over the nature of sunspots demonstrating them to be on the sun’s surface and not orbiting it as Scheiner first proposed. Scheiner graciously acknowledged that Galileo was right and he was wrong but this did not stop Galileo falsely accusing Scheiner of plagiarism in his Il Saggiatore (1623) and then publishing some of Scheiner’s observations as his own in his Dialogo (1632).
Whereas Galileo only observed the sunspots for a brief period around 1613, Scheiner devoted many patient years to observing the sun publishing his observations in his Rosa Ursina sive Sol (1626–1630). Scheiner’s book remained the definitive work on solar astronomy until the nineteenth century so probably he would have been the best historical comparison for Hisako Koyama’s achievements.