Northern lights might put on a repeat show
The strongest solar storm in over 20 years produced remarkable displays above California this weekend, with the northern lights illuminating the night sky in surprising shades of red. Some lucky residents captured the light show and flooded social media with images, while others may be left wondering if there will be another chance to glimpse an aurora in California.
While such a historic event is uncommon, scientists say the coming months bring heightened potential for geomagnetic storms impacting Earth and higher chances for auroral activity over the state.
“If you were to pick particular times when it would be most likely, that’s this year and next year,” said Sushant Mahajan, a solar astrophysicist at Stanford University and part of the NASA Solar Dynamics Observatory team.
Solar activity ebbs and flows over an 11-year cycle due to changes in the sun’s magnetic field as it rotates.
“Different parts (of the sun) don’t rotate at the same rate,” said Andrew Fraknoi, an astronomy professor at the Fromm Institute at the University of San Francisco.
These different rotation speeds stretch and wind up the magnetic field inside the sun.
“When this magnetic field then unravels, it releases some of that energy … it’s like a few million atomic bombs going off in a few seconds,” Mahajan explained.
The sun is currently at solar maximum, when such activity is highest during the 11-year cycle.
This weekend’s geomagnetic storm resulted from multiple blasts of charged particles from the sun, directed right toward Earth. These added up to produce intense impacts on Earth, said Ian Cohen, a chief scientist who studies heliophysics at the Johns Hopkins Applied Physics Laboratory
But experts don’t know if solar activity will continue to rise: “Our activity levels have already exceeded where we thought they would be,” Cohen said. “We don’t have a good sense of knowing if we’re still on the leading edge and we’re rising and we’re going to have a really intense cycle, or if maybe we’re already at the peak.”
Though odds aren’t high for an encore of last Friday’s historically intense storm, it’s still possible that the stars will align for Californians to see the northern lights again.
“The way the sun’s flexing right now,” Cohen said. “I don’t think I would bet against it.”