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Space hurricanes swirl in the Southern Hemisphere, mostly in summer

Space hurricanes are a recently discovered geomagnetic phenomenon in which plasma interacts with Earth's magnetosphere, the area of space dominated by Earth's magnetic field. Spiral arms of plasma, hundreds of kilometers long, stretch across the sky and turn clockwise around a calm "eye" in the center—forming aurorae shaped much like the hurricanes that occur closer to Earth's surface in the troposphere. Electrons from space rain down into Earth's upper atmosphere, where they have the potential to disrupt satellite communications.

Scientists first found evidence of space hurricanes in 2021 while combing through satellite imagery. All were detected over the Northern Hemisphere, where there is more scientific instrumentation and observation. Previous work found that about 12 space hurricanes hit the Northern Hemisphere each year. Now, Sheng Lu and colleagues present the first analysis of how frequently space hurricanes occur in the Southern Hemisphere, dovetailing with the group's previous work to improve understanding of when, where, and why space hurricanes strike.

The researchers combed through satellite imagery taken between 2005 and 2016 and identified 259 space hurricane events. Space hurricanes in the Southern Hemisphere look and behave much like their northern counterparts, suggesting they're driven by similar mechanisms, the researchers found.

Space hurricanes hit the Southern Hemisphere most frequently in the summer, potentially because of the planet's magnetic tilt and the levels of sunlight exposure. But like northern storms, they mostly occur at latitudes above 80° (over Antarctica), so the odds of glancing up and seeing such a storm are small. The study also found that the average velocity of plasma near space hurricanes is about 1 kilometer per second (a whopping 3,600 kilometers per hour, or 2,237 miles per hour). This is about 10 times faster than the normal speed of plasma in the polar cap, the authors said.

The findings set the stage for further explorations of space hurricanes, including their 3D characteristics and impacts on the lower atmosphere. Ultimately, the researchers hope to establish a reliable method to forecast these events.