Solar eclipse offers rare chance to solve Sun’s magnetic-field mysteries

On 12 August 2026, a total solar eclipse will sweep across Greenland, Iceland, and parts of Spain, offering scientists a unique opportunity to study the Sun's corona, the outermost layer of the star, during a brief two-minute window when the Moon completely blocks the Sun's disk. Researchers from multiple countries plan to travel to these regions to collect data that could shed light on long-standing questions about the Sun’s magnetic field and the extreme temperatures observed in the corona, which are hundreds of times hotter than the Sun’s surface. This eclipse marks the first of two consecutive total solar eclipses in the coming years, with the second occurring on 2 August 2027. Scientists view these events as rare opportunities to conduct ground-based observations that complement data gathered by space-based instruments. During the eclipse, the corona becomes visible to the naked eye, allowing researchers to analyze its structure and composition in greater detail than ever before. The solar corona consists of superheated plasma reaching temperatures of up to one million degrees Celsius. Under normal conditions, the corona is too faint to be seen against the bright light of the Sun’s surface. However, during a total eclipse, the Moon acts as a natural occulting disk, blocking the Sun’s light and revealing the corona. This phenomenon allows scientists to study the corona directly, capturing detailed images and spectral data that are difficult to obtain through artificial methods used in space or on the ground. Amir Caspi, an astrophysicist based in Boulder, Colorado, leads one of the research teams planning to observe the eclipse. He emphasizes the significance of studying the corona, stating that scientists aim to understand the origin of the Sun’s magnetic energy and how it is transported to heat the corona to such extreme temperatures. His team, along with others, hopes that insights gained from this observation will contribute to improved models of solar activity and enhance predictions of space weather events. Shadia Habbal, an astronomer from the University of Hawaii, has participated in nearly 20 eclipse expeditions since 1995. For this particular event, she plans to establish five observation sites, two in Iceland and three in Spain, to increase the likelihood of successful data collection despite potential challenges posed by cloud cover. Her team will employ advanced equipment, including spectrometers and high-resolution cameras fitted with specialized filters, to capture light emissions from the corona at specific wavelengths. These measurements will help identify the types of chemical elements present and their ionization states, providing critical clues about the corona’s temperature and structure. Understanding the dynamics of the solar corona is crucial for predicting space weather phenomena such as geomagnetic storms, which can interfere with satellite communications and cause disruptions to power grids on Earth. A notable historical example occurred in 1989, when a geomagnetic storm led to a widespread power outage affecting six million people in Canada. Currently, scientists can detect coronal mass ejections days in advance but often have limited time to assess whether they pose a threat to Earth until the plasma reaches a monitoring satellite, which provides warnings just minutes before impact. Improved knowledge of the corona’s behavior could lead to more accurate forecasts and better preparedness for such events. As the date of the eclipse approaches, researchers are finalizing their equipment and logistical arrangements. Their findings will be analyzed alongside data from previous eclipses and ongoing solar missions to build a more comprehensive picture of the Sun’s magnetic field and its influence on space weather. The upcoming observations represent a pivotal moment in solar physics, with the potential to unlock new insights into the mechanisms driving the Sun’s complex and dynamic environment.