New research led by the U.S. National Science Foundation’s National Center for Atmospheric Research (NSF NCAR) has uncovered new insights into the possible presence of polar vortices on the Sun. These findings, published in the Proceedings of the National Academy of Sciences, suggest that, like Earth, the Sun likely has swirling polar vortices, though driven by magnetic fields rather than atmospheric dynamics. This research could significantly enhance our understanding of the Sun’s magnetism and its solar cycle, offering valuable information for predicting space weather events that affect Earth.
The concept of polar vortices on the Sun may initially seem surprising, but they are not unique to our star. Polar vortices are swirling, rotating features that form in fluids surrounding rotating bodies, driven by the Coriolis force. On Earth, for example, polar vortices are a well-known feature of the atmosphere, spinning around the North and South Poles. These vortices are responsible for trapping cold air at the poles, but when they weaken, cold air can escape toward the equator, leading to sudden cold outbreaks in the mid-latitudes. Similarly, polar vortices have been observed on other planets such as Jupiter, Saturn, and Mars, as well as on moons like Titan.
However, the Sun is not like other planets or moons—it doesn’t have a traditional atmosphere. Instead, its “fluid” is plasma, a hot, electrically charged gas, and this difference raises the question of how magnetism might influence vortex formation on the Sun. The Sun’s plasma is inherently magnetic, and the magnetic field plays a central role in many solar phenomena, including sunspots, solar flares, and coronal mass ejections. Despite these similarities, no mission has yet been able to directly observe the Sun’s poles, which remain a mystery. Most observations of the Sun come from its equatorial region or from Earth-based telescopes, giving scientists only limited insight into the behavior at the poles.
To investigate the potential presence and behavior of solar polar vortices, researchers used high-performance supercomputing models to simulate the Sun’s magnetic field and plasma dynamics. The simulations suggest that the Sun likely has a unique type of polar vortex, one that forms and evolves in connection with the Sun’s solar cycle. The solar cycle, which lasts about 11 years, involves periodic changes in the Sun’s magnetic activity, including the shifting and flipping of the Sun’s magnetic poles.
According to the simulations, a ring of polar vortices forms around 55 degrees latitude on the Sun, which is roughly equivalent to Earth’s Arctic Circle. This formation coincides with a phenomenon known as the “rush to the poles,” where the magnetic field at the Sun’s equator begins to move toward the poles. As the magnetic field reverses during solar maximum, the vortices in the simulation tighten and head toward the poles. As they move closer to the poles, some vortices shed off until only two vortices remain directly at the poles, before disappearing altogether during the peak of solar maximum. The number and configuration of these vortices appear to vary depending on the strength of the solar cycle.
These findings provide crucial new information about the Sun’s magnetic behavior near its poles and could help resolve longstanding questions about the solar cycle. For instance, scientists have long used the strength of the magnetic field that moves toward the poles as a way to predict the intensity of the upcoming solar cycle. However, the relationship between the field’s strength and the cycle’s behavior has not been fully understood. The new research offers insights into how the formation of vortices could be linked to the Sun’s overall magnetic activity.
In addition to enhancing our theoretical understanding of solar dynamics, these findings also have practical implications for planning future solar missions. While current space missions like the Solar Orbiter, a collaboration between NASA and the European Space Agency (ESA), aim to provide close-up views of the Sun’s poles, they will likely encounter the poles during solar maximum, when the vortices are expected to be least visible. The simulations indicate that polar vortices should be observable throughout much of the solar cycle, except during the peak of solar maximum when they disappear. This timing is crucial for planning missions to observe the solar poles and gain the most valuable data.
Scott McIntosh, a co-author of the study, highlights the importance of having multiple viewpoints to observe the Sun. The current conceptual limit is that we only have one perspective, typically from Earth or a single spacecraft, and this hinders our ability to fully test hypotheses about solar behavior. With the right data and the ability to observe the solar poles from different angles and times, researchers could make significant progress in understanding solar magnetic fields and their effects on space weather.
This new research opens the door to further investigations into the Sun’s polar vortices and their role in solar magnetic activity. By improving our understanding of the Sun’s behavior, we may be able to better predict space weather events, which can have significant impacts on communication systems, satellites, and even power grids here on Earth. As more missions are launched to observe the Sun in greater detail, these insights will be invaluable in ensuring that we are prepared for the Sun’s unpredictable and powerful activity.