The sun has fired a second massive solar storm in two days directly towards the Earth.
As it nears 'Solar Maximum', the regular period in which solar activity is most intense, it is more likely that Earth will come under bombardment from billions of tons of charged particles.
But Nasa says that the attacks do not represent a threat to humans.
The eruption - a Coronal Mass Ejection - sent particles towards Earth at 280 miles a second yesterday morning, at about 6 am UK time.
It will reach Earth sometime over the weekend, Nasa said.
"These particles cannot travel through the atmosphere to harm humans on Earth, but they can affect electronic systems in satellites and on the ground," Nasa said in a statement.
"Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they funnel energy into Earth's magnetic envelope, the magnetosphere, for an extended period of time."
SpaceWeather.com reported that the CMEs are expected to hit Earth on August 23 and 24, and warned that geomagnetic storms could be sparked around the poles.