Solar eclipse: What to look forward to

On Wednesday, scientists will conduct a rare opportunity to study the sun during a total solar eclipse, which will stretch across Greenland, Iceland, and Spain. This celestial event offers researchers a unique chance to examine the sun's corona, the outer atmosphere, using specialized instruments aboard a research aircraft and high-altitude balloons launched from Iceland. The eclipse will allow for observations that could help solve long-standing mysteries in solar physics, particularly regarding the extreme temperatures found in the corona. The path of the total eclipse begins over Greenland and moves southward through Iceland before reaching Spain. In Germany, observers will witness a partial eclipse, with the sun obscured by up to 90 percent in the far southwest. During this time, the moon’s shadow will travel across Earth at approximately 2500 kilometers per hour, creating a narrow band of darkness that lasts only a few minutes anywhere on the ground. However, a specially equipped aircraft operated by NASA plans to follow the shadow’s movement from Iceland, extending the duration of total eclipse conditions experienced by the crew to nearly three minutes. The corona, despite being millions of degrees hotter than the sun’s surface, has puzzled scientists for decades. Researchers hope data collected during the eclipse will provide insights into how this heating occurs. Onboard the aircraft, a camera will capture 20 high-resolution images of the corona each second, offering detailed visual information about its structure and dynamics. In addition to the airborne observations, two research teams in Iceland plan to launch around 80 balloons within an 18-hour window before and after the eclipse. These balloons aim to investigate how the eclipse affects the boundary layer of the Earth’s atmosphere, where air meets the surface. Factors such as temperature and humidity influence the thickness of this layer, according to NASA. Space-based observatories like the Solar Orbiter and SOHO will also take advantage of the eclipse. Normally, these satellites use artificial occulters to block the bright disk of the sun, simulating an eclipse to observe the corona. However, due to safety concerns, the size of these occulters must exceed the sun’s diameter to prevent damage from stray light. As a result, these instruments typically begin observing the corona only at distances greater than half a solar radius from the surface. During a total eclipse, however, the absence of direct sunlight allows for unimpeded views of the corona down to the sun’s surface. The Solar Orbiter, positioned roughly 90 degrees away from Earth’s direction, will offer a different perspective of the sun. According to Daniel Müller, a solar expert from the European Space Agency, this angle will enable the creation of stereoscopic, three-dimensional images of structures within the corona. Such imagery can enhance understanding of solar phenomena and their evolution. Historically, total solar eclipses have played a crucial role in scientific discovery. Before the space age, they were the primary means for studying the corona. One notable example was the total eclipse of July 8, 1842, observed from southern France, northern Italy, and Austria. It marked the beginning of systematic astronomical studies during eclipses, with astronomers traveling to the zone with telescopes and measuring devices. Another pivotal moment came during the May 29, 1919, eclipse, which provided critical evidence supporting Einstein’s theory of relativity. Observations of starlight bending near the sun confirmed predictions made by the theory, marking a turning point in modern physics. Today, similar opportunities continue to drive advancements in solar science, using both traditional and cutting-edge methods to explore the complexities of our nearest star.