The heavy-duty flare erupted on the surface of the sun mid-morning Thursday, and early data suggest it generated a so-called coronal mass ejection of gas and magnetic fields , researchers said.
"It looks to be headed in the Earth's direction," Alex Young of Maryland's Goddard Space Flight Center told the Los Angeles Times.
Scientists said more data from spacecraft would pinpoint the speed and severity of the storm.
The ejection, traveling at speeds of 1 million to 5 million mph, would reach Earth in about one to three days, Young said.
The stream of electromagnetic radiation can cause radio blackouts, he said, and in more extreme cases can disrupt power distribution and play havoc with satellite communications.
More such events are likely headed our way in the near future, Young said, as the sun is nearing a peak in its solar activity cycle.
"Solar activity has a cycle, minimum to maximum to minimum, and it's getting close to the peak of solar maximum," he said, with the peak of the eleven-year cycle expected to occur sometime in 2013 or 2014.