Occurrences of total solar eclipses are historically valuable moments for the scientific community, providing unique chances for progress in multiple areas of research. A striking example of this was the observation made by British astronomer Arthur Eddington in 1919, who used the phenomenon off the coast of West Africa to validate Albert Einstein’s theory of relativity.
This dynamic was repeated today, when the singular astronomical event covered regions of the Northern Hemisphere, ranging from northern Russia to Spain and Portugal. For months, experts in fields such as biology and astrophysics dedicated themselves to intensive preparations, seeking to gather crucial information during the brief moments of darkness.
In Spain, while many observers directed their attention to the sky, a team of scientists focused in another direction. The objective was to investigate how local flora and fauna react to the eclipse.
This area of study remains under-investigated, with limited knowledge about the effects of abrupt and momentary darkness on these organisms. The rare previous research suggests that plants and animals respond to the stimuli present during the phenomenon.
Airam Rodríguez, researcher at the National Museum of Natural Sciences in Spain, details that “the impacts on each species vary depending on the individual’s cognitive level.” He cites reactions that range from fright and the search for refuge to behaviors like that of chimpanzees, which can point to the sunset, or moving to rest areas.
Rodríguez is one of the founders of EcoEclipse, an innovative initiative in Europe focused on this field of research. His team’s work includes recording environmental sounds two days before, during the eclipse and on the two days after, allowing comparisons of the species’ behavior at different periods.
He adds that “data on reactions will be made available in raw format”, with the aim of allowing other scientists, in the future, to analyze changes in environmental noise, and not just sounds originating from animals.
Although several species have their reactions recorded, the project currently prioritizes birds, which have daily and seasonal cycles strongly influenced by the transition between light and shadow, and bats. “Our knowledge about bats is even scarcer, and the advantage of this eclipse is that, as it occurs at dusk, its effects can be amplified on these animals”, explained the expert.
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In 2024, during a total solar eclipse in the United States, scientists had already monitored birdsong. On that occasion, a mobile application was launched that encouraged popular participation in data collection.
This effort revealed 52 species of birds, 29 of which exhibited notable changes in their vocalization. These changes ranged from complete silence or the beginning of singing, to a “false dawn chorus” the moment sunlight returned.
One of the most comprehensive analyzes ever released was conducted at a United States zoo in 2017, during another eclipse. In the two and a half minutes of complete darkness, the responses of several animals were observed, including primates, elephants, brown bears, seals, flamingos, parrots, cockatoos and turtles.
The result surprised the researchers: 76% of the 17 species analyzed showed some type of reaction. Some animals began activities characteristic of the night, others expressed anxiety, and some exhibited unprecedented behaviors.
On the other hand, the reactions of plants are largely unknown, even with some previous investigations that attempted to record the effects of eclipses on them.
In 2022, an observation during a partial eclipse in northern Italy indicated that trees could anticipate the phenomenon. They would have synchronized, hours in advance, their bioelectric behavior, which are internal signals that control vital functions such as photosynthesis and defense mechanisms.
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However, subsequent studies showed that it was not possible to prove a direct connection between eclipses and the bioelectric signals emitted by plants.
Biologist and writer Aina S. Erice comments that “perhaps there are plants that clearly react to eclipses, but we haven’t studied them yet.” She reinforces that, with more than 300 thousand plant species catalogued, this possibility cannot be ruled out.
Simultaneously, in Italy, scientists dedicated weeks in a laboratory to improve new equipment. This instrument has the potential to revolutionize the analysis of the solar corona, the outermost region of the Sun’s atmosphere.
During the eclipse, the Circular Slit Spectrometer (CISS) underwent a crucial test at the Javalambre Astrophysical Observatory in Spain. The developers aim to demonstrate that the device can fragment sunlight into its wave components in a significantly more agile way than current technologies.
The eclipse phenomenon provides ideal conditions for the solar corona to become more noticeable. This facilitates studies of this area close to the Sun, whose behavior can have major implications for communication networks and electrical energy systems on Earth.
Federico Landini, principal researcher at the Turin Astrophysical Observatory, explained that, unlike traditional linear spectrometers, the new prototype “has a circular slit, making it possible to record the spectrum of the entire corona at a specific distance from the center of the Sun in just one image.”
The last large ultraviolet spectrometer, the UVCS, was used on the SOHO probe, a collaboration between the European Space Agency (ESA) and NASA, between 1996 and 2013. However, it required many hours to be able to completely map the solar corona.
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If scientists demonstrate the effectiveness of this new optical principle, the next step will be its possible incorporation into a future space mission. This mission will focus on detailed observation of the Sun’s outer atmosphere.
At the same time, researchers from the French Atomic Energy Commission (CEA) used the eclipse as a chance to investigate the Sun’s magnetic field, its atmosphere and the intense events that occasionally result in disruptions on Earth.
The Sun continually emits matter and charged particles, sometimes generating severe solar storms that project large explosions of plasma and other elements into space.
When this material reaches Earth’s magnetosphere, it can cause satellite failures, expose astronauts to danger, and create bright aurora borealis and australis in high latitude regions.
Allan Sacha Brun, astrophysicist at CEA, explained that “our effort is aimed at understanding the physical mechanisms behind solar activity.” He adds that this entails “placing the Sun in its proper context in the timeline of its evolution, from its emergence to its end.”
Meanwhile, scientists from the European Space Agency (ESA) examined the eclipse with the aim of deepening knowledge about solar winds. Carole Mundell, the agency’s director of science, raised questions such as: “Why do solar storms disperse in a certain way? What is their configuration? And is it feasible to create models that allow them to be predicted?”
ESA’s Solar Orbiter probe, in orbit since 2020, has been collecting important data about the atmosphere and solar winds. Miho Janvier, co-principal investigator on the mission, commented that eclipses serve as a chance to “evaluate the accuracy of our models, whether they are good or not.”
Another ESA initiative, the Proba-3 mission, currently employs three spacecraft that fly in precise formation, with the purpose of generating their own smaller-scale artificial solar eclipses.