Stargazers looking to the sky late Tuesday night and early Wednesday morning could catch a glimpse of northern lights, according to the Harvard-Smithsonian Center for Astrophysics. The potential light show started on Sunday, when the sun’s surface erupted and hurled tons plasma into space. Astronomer Leon Golub of the CfA said this is the first major Earth-directed eruption in some time. When such an expulsion reaches Earth, it interacts with the planet’s magnetic field and can create a geomagnetic storm. Solar particles stream down the field lines toward Earth’s poles, and crash with atoms of nitrogen and oxygen in the atmosphere, glowing like neon signs. Sky watchers in the northern U.S. and other countries should look toward the north late Tuesday or early Wednesday for rippling “curtains” of green and red light, the CfA said.