The largest solar flare in five years is racing toward Earth, threatening to unleash a torrent of charged particles that could disrupt power grids, GPS and airplane flights.

The sun erupted Tuesday evening, and the effects should start smacking Earth around 7 a.m. EST Thursday, according to forecasters at the federal government’s Space Weather Prediction Center. They say the flare is growing as it speeds outward from the sun.

“It’s hitting us right in the nose,” said Joe Kunches, a scientist for the National Oceanic and Atmospheric Administration. He called it the sun’s version of “Super Tuesday.”