The sun emitted its strongest flare in seven years Thursday morning, NASA officials said, and it’s at least possible that the elusive northern lights may be visible this weekend as far south as Pennsylvania, with an outside shot that the Philly region gets to see the show.

For prime northern lights viewing in the United States, the strongest activity is forecasted to arrive late Friday night to Saturday morning. Clouds may also clear through the night to provide good vantages for the majority of the country, especially in the Midwest and Mid-Atlantic.