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The sun is in its solar maximum, a period characterized by intense solar outbursts and eruptions of charged particles directed toward Earth. These flare-ups significantly affect our low Earth orbit satellites, causing them to change position in a worrying manner.

This year, Earth has experienced two geomagnetic storms caused by a series of solar eruptions. The solar storms affected the orbits of thousands of satellites, resulting in an unprecedented mass migration, said William Parker, a researcher at the Massachusetts Institute of Technology, during a presentation at the annual meeting of the American Geophysical Union, SpaceNews. reported.

Geomagnetic storms are disturbances in Earth’s magnetosphere – a large bubble of magnetic field around our planet – caused by solar wind. Last May, a G5, or extreme, geomagnetic storm hit Earth as a result of large expulsions of plasma from the Sun’s corona (also known as coronal mass ejections). The G5 storm, the first to hit Earth in more than two decades, caused some damaging effects on the Earth’s electrical grid and some spectacular auroras that can be seen across much of the world.

The storm increased the atmospheric density in low Earth orbit by an order of magnitude, which in turn caused atmospheric drag that Parker said affected the satellites. The resulting migration of satellites was most noticeable in SpaceX’s Starlink constellation, which includes more than 6,700 satellites in low Earth orbit.

“SpaceX saw a position error of 20 kilometers (12.4 miles) in their one-day calculations,” Parker said in SpaceNews. “If we’re not sure where our spacecraft is 12 miles away, you can throw collision avoidance out the window.” The researcher is referring to the risk of satellites in low Earth orbit colliding with each other, a danger that is usually avoided by carefully monitoring the positions of spacecraft in orbit. The small shift in a satellite’s orbit brings a greater risk of collision.

After the storm’s peak, some satellites performed automated maneuvers to return to pre-storm altitude, correcting shifts caused by the event. One day after the storm, nearly 5,000 satellites, mostly Starlink, performed orbit-raising maneuvers, according to Parker.

“This is half of all active satellites that decide to maneuver at once,” he said. “This makes it the largest mass migration in history.” The maneuvers make it even more difficult to predict where the satellites will be apart, increasing the risk of collisions.

Scientists are still trying to understand the sun’s behavior to better predict the occurrence of these geomagnetic storms, which would help satellite operators prepare their hardware in space.