The Sun has unleashed its most powerful eruption of 2013 so far.
The solar flare - a sudden release of radiation - peaked at 1705 BST on Monday, and was associated with a huge eruption of matter.
When these eruptions reach Earth, they can interfere with electronic systems in satellites and those on the ground.
Nasa said this solar explosion - known as a coronal mass ejection (CME) - was not directed at Earth, but it could pass several US spacecraft.
The event on Monday was classified as an "X-class" flare - the most intense type - with a designation of X2.8 (higher numbers denote a stronger flare). It surpassed an X1.7-class flare that occurred 14 hours earlier.
They are the first X-class events to occur this year.
When intense enough, a flare can disturb the Earth's atmosphere in the layer where GPS and communications signals travel.