A powerful flare erupted from the sun Thursday, unleashing a plasma wave that may supercharge the northern lights for skywatchers in high latitudes this weekend. The solar flare at 11:30 am Eastern touched off a massive solar explosion -- known as a coronal mass ejection -- aimed at Earth that should arrive by Saturday night. "High-latitude (and possibly middle-latitude) sky watchers should be alert for auroras this weekend," the skywatching website Spaceweather.com said in an alert.
