A total solar eclipse will be visible across parts of Spain on August 12, marking the first such event in mainland Europe since 1999. Researchers and volunteers plan to collect data on the solar corona, animal behavior, and human physiological responses.

Eclipses have been observed since antiquity, with the earliest known record on a clay tablet from Ugarit, Syria, dating to 1223 BCE. Ancient cultures interpreted the phenomenon as omens, while modern science uses eclipses to study celestial mechanics and solar physics.

The 1868 discovery of helium in the Sun’s spectrum and the 1919 observations that confirmed Einstein’s theory of general relativity illustrate the scientific value of eclipses. The solar corona, identified in 1842, shows temperatures of up to 1.5 million kelvin, far higher than the Sun’s surface temperature of about 5,800 kelvin. Modern instruments such as coronagraphs can partially mimic an eclipse, but the Moon remains the most effective natural mask for observing the solar disk.

Astrophysicist Antoine Strugarek noted that the Sun’s brightness makes edge observations difficult, comparing it to “watching a fly buzzing next to a car headlight.” He added that studying the corona is essential because solar activity influences Earth’s magnetosphere, ionosphere, satellites, astronauts, and aviation.

In Spain, scientists will position themselves along the path of totality to capture images, while French researchers will conduct partial observations to test predictive models. A team of Spanish ecologists has launched the EcoEclipse project, recruiting 300 volunteers to record animal sounds and behavior before, during, and after the eclipse, with a focus on birds and bats. The project hypothesizes that bats may become active earlier than usual because the sudden darkness resembles night.

Other species, including elephants, lions, primates, and bears, will be monitored by the Iberian Association of Zoos and Aquariums across 12 Spanish zoos located along the eclipse path.

Human responses have also been studied. A 2017 analysis of nearly three million social media posts from the United States showed that observers within the path of totality expressed greater awe and used more prosocial, collective language. A 2023 biometric study in New Mexico recorded brainwave variations consistent with awe during an annular eclipse. Catalan researchers will repeat a large‑scale citizen science effort called Project Solaris, collecting smartwatch data from 5,000 volunteers to examine changes in heart rate and breathing during the eclipse. Eduard Masana, a Catalan astrophysicist, said the project aims to bring science closer to society, while Maria Jesus Cruz Carmona of the Vall d’Hebron Research Institute noted that the sudden darkness and temperature drop may have physiological effects that warrant study.

The eclipse provides a brief but valuable opportunity to address long‑standing questions about the solar corona’s temperature and to explore how collective experiences shape human emotions and animal behavior.