The northern lights were visible throughout much of the northern U.S. late Thursday after a solar flare produced a geomagnetic storm.Forecasters had said that the aurora borealis had the potential to be visible as far south as the Carolinas and California.Throughout the northern half of the U.S., green and purple hues of light could be seen in the night sky. The northern lights became even more vibrant for many as the moon set late in the evening.RELATED STORY | 'Absolutely unreal': Astronaut witnesses aurora from spaceThe aurora came after officials issued a geomagnetic storm watch.The Space Weather Prediction Center said that a severe geomagnetic storm can cause issues on the ground. Severe geomagnetic storms can cause electric grids to have "possible widespread voltage control problems, and some protective systems will mistakenly trip out key assets from the grid." The agency says spacecraft "may experience surface charging and tracking problems; corrections may be needed for orientation problems."Auroras are caused by the solar wind interacting with Earths magnetic field. These auroras tend to navigate around the Earths magnetic poles.The solar wind particles funnel around to the long tail of the magnetosphere, where they become trapped, NASA said. When magnetic reconnection occurs, the particles are accelerated toward Earths poles. Along the way, particles can collide with atoms and molecules in Earths upper atmosphere, an interaction that provides the atoms with extra energy, which is released as a burst of light. These interactions continue at lower and lower altitudes until all the incoming energy is lost. When we see the glowing aurora, we are watching a billion individual collisions, lighting up the magnetic field lines of Earth.Will aurora be seen Friday night?The geomagnetic storm is continuing on Friday, but forecasters say early indications say conditions are dying down. The Space Weather Prediction Center predicts that aurora could be visible in the northernmost reaches of the contiguous U.S., including Maine and parts of Michigan and Minnesota.RELATED STORY | Massive star offers new details on the most magnetic objects in spaceHowever, aurora forecasts can change, and forecasters could update their predictions later today.