A magnetic cloud hurled from the sun underwent a dramatic expansion as it journeyed toward Earth, growing by roughly a fifth of its original size. The finding comes from a University of Iowa-led physics team that analyzed data captured by multiple spacecraft positioned at fortuitous points along the cloud's path.
The phenomenon, which the researchers have termed a "super expansion," occurred over a span of about 13 million miles (21 million kilometers). Plasma inside the ballooning structure heated up during the process, offering new insights into how such solar ejecta evolve before reaching our planet.
According to the study, the cloud's size increase was extreme compared to typical magnetic cloud behavior. The team relied on readings from spacecraft fortuitously located to record the cloud at different stages of its approach, providing a rare multi-point view of the event.
The findings could improve forecasts of space weather impacts on satellites and power grids. Understanding how magnetic clouds inflate may help predict how much energy they deliver when they strike Earth's magnetic field.
The authors caution that this single event may not represent all magnetic clouds. Further observations are needed to determine whether super expansion is a common occurrence or unique to particular solar conditions.