A total solar eclipse occurs when the moon passes directly in front of the sun. It then almost completely covers the bright solar disk. Only the corona remains visible – the outer atmosphere of the sun, which reaches far into space. It is millions of degrees hotter than the sun’s surface, but much dimmer. Therefore, it is usually outshined by the bright solar disk. Only a solar eclipse makes it possible to observe this hot gas envelope as a luminous corona.
Astronomers got a chance to observe new details of the solar corona on April 20, 2023. On this day, a total solar eclipse occurred, which was clearly visible in western Australia. This photo shows the eclipsed Sun at the peak of totality.
In order to obtain as many images as possible of this eclipse, which lasted only a few minutes, astronomers had already asked for the help of laypersons as part of the citizen science project CATE. “Although it was a very brief eclipse, our team of citizen scientists did a flawless job, capturing great images of the structure of the elusive solar corona,” said Amir Caspi, of the Southwest Research Institute (SwRI) in Colorado. The images made the colors and structures of the vortices and currents clearly visible in the sun’s atmosphere, which is millions of degrees hot.
The aim was to examine the dynamic outer atmosphere of the sun and to gain insights that are not possible or practicable with other methods. This research is helping to understand the complexities of the solar corona – including its intricate shape, how it changes over time, and the reasons for its high temperatures.
The CATE experiment served not only as a standalone study, but also as a training exercise for the solar eclipse visible in the United States next year. “This eclipse provided the perfect opportunity to test our equipment and procedures, and to train our community leaders for the next eclipse in 2024,” Caspi said. The project is scheduled to record a 60-minute high-definition video on April 8, 2024. It enlists the help of 35 citizen scientist teams from local communities along the shadow path of the eclipse.
Another important goal of the project is to bring the public and academia together and share the results with the next generation of young scientists. In this way, understanding can be expanded and a broader audience can be excited about solar research. In the fall of 2023, the project will begin recruiting teams from communities along the US eclipse path.