The magazine, kept in a house in the US state of Maine for over 200 years, has revealed the secrets of the solar past. Discovered pages of early observations could shed light on the solar cycle.
In 1816, the Northern Hemisphere experienced the so-called “year without summer”. Jonathan Fischer, a Congregational minister who has devoted part of his life to working at Harvard University, suggested that the sun was to blame. From June 1816, he began making detailed drawings of sunspots in his journal.
Michael McVeow, a historian at the University of North Carolina at Chapel Hill, and his colleague William Denig of the National Oceanic and Atmospheric Administration (NOAA) published an article in Space Weather describing the discovery of sunspot patterns in Fisher's journals.
A year without summer
In April 1815, the Tambora volcano erupted in Indonesia, releasing ash, sulfur dioxide and the formation of aerosols, which prevented the penetration of sunlight. As a result, the sharp jump in temperature led to severe agricultural losses in Europe and North America, causing widespread famine.
According to Denig and McVough, scientists around the world have hypothesized that the sun plays a key role in extreme temperature changes, unaware of the connection between the eruption and the weather. The low number of sunspots present in the sun at the time seemed to support this hypothesis, as the sun went through a phase of minimum activity in accordance with its 11-year cycle.
"Fischer was an educated person and it is likely that he guessed about the connection between low temperatures and sunspots," the authors write.
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Two weeks after a thick blanket of snow covered his house in Blue Hill, Maine in June 1816, Fisher began drawing sunspots in his journal. He continued to sketch until the summer of 1817, when the weather returned to normal.
“The impetus for the observations was the weather, not the sunspots themselves. At that time, science was not yet a profession, and few people were engaged in such work. Only a handful of enthusiasts in the Americas had observed sunspots prior to 1816, and Fischer was the only person who kept records of sunspots in the region during this fateful year,”McVough explained.
Hacking the archive
Fischer's journals have been on display in his historic home for centuries. But even in his youth, he developed a secret code to protect his archive. “It wasn't until 1940 that someone very capable and patient was able to decipher his shorthand,” said McVow, who works as a tour guide in the house and reviewed an unillustrated digital copy of a translation of his journals in preparation for a series of discussions about a year without summer.
"I decided to look at the originals that are still in Fischer's house and found that he was making regular drawings of the sun in his magazine to illustrate his theory of sunspots and their relationship to extreme weather."
These blueprints, now available online from NOAA's website, reveal a new way of tracking how sunspots have evolved over time. “Knowing the solar cycle depends on how much information we can get over extended periods of time. Fischer's observations are contributing to new and completely unprecedented ways of solving this problem,”concluded the author.
