NASA’s Parker Solar Probe has made significant strides in unravelling a long-standing puzzle about the sun. The spacecraft has delivered new insights into why the sun’s outer atmosphere, known as the corona, is much hotter than its surface. This enigma, known as the “coronal heating mystery,” has baffled scientists for decades.

Discoveries from the Parker Solar Probe

The Parker Solar Probe, the fastest human-made object, has now completed 20 close passes by the sun. During these encounters, it collected data revealing abrupt reversals in the direction of the sun’s magnetic fields, termed “switchbacks.” These switchbacks might be crucial in understanding how the corona is heated. Researchers speculate that the energy released by these magnetic field reversals could contribute to heating the corona and accelerating the solar wind.

Despite the photosphere being closer to the sun’s core, where nuclear fusion occurs, the corona’s temperature is hundreds of times higher. The Parker Solar Probe’s data has shown that switchbacks are common in the solar wind close to the sun. However, they are not observed to originate from the corona itself, which discounts one of the leading theories about their role in coronal heating.

Unraveling the Heating Mechanisms

Scientists are exploring alternative mechanisms that could explain the corona’s high temperatures. One possibility involves explosive collisions of chaotic magnetic field lines on the sun’s surface. These collisions might create vibrations similar to plucked guitar strings, accelerating plasma in the solar wind to high speeds. If some magnetic waves lose energy before escaping the sun, this energy might be deposited in the corona, contributing to its heating.

The Parker Solar Probe’s findings refine our understanding of the sun’s behaviour and have implications for predicting solar storms. The probe’s mission, which began in 2018, continues to provide valuable data. It will return to proximity to the sun on September 30 and approach even further on Christmas Eve this year. Each close pass offers new opportunities to uncover the secrets of the sun’s corona and its dynamic processes.