A solar storm that had the potential to cause havoc with satellites or power grids has passed without incident.
Nasa had warned that the biggest space weather storm in five years was heading towards Earth and could disrupt power grids, GPS systems, satellites and airline flights.
In a statement on its website, the US space agency said the storm was caused by two solar flares that erupted on Sunday .
Following the flares, two bursts of solar wind and plasma - known as a coronal mass ejection (CME) - were thrust towards Earth.
"The first is travelling faster than 1,300 miles per second; the second more than 1,100 miles per second," the statement added.
The brunt of the storm was expected to last until Friday.
A similar storm in January forced Delta airlines to divert flights across the polar regions.
"Space weather has gotten very interesting over the past 24 hours," said Joseph Kunches, a space weather scientist with the National Oceanic and Atmospheric Administration (NOAA).
The solar flares alone caused brief high frequency radio blackouts that have now passed, according to the NOAA .
The storm is likely to be "the strongest one since December 2006," Kunches said, despite admitting the Earth experienced a stronger radio blackout last August.
"But en masse, if you put it all together with the geomagnetic effects and the solar radiation effects, I would put it on par with one at the end of the last solar cycle, which was over five years ago."
Space storms are not new. The first major solar flare was recorded by British astronomer Richard Carrington in 1859.
Other solar geomagnetic storms have been observed in recent decades. One huge solar flare in 1972 cut off long-distance telephone communication in the US state of Illinois.
Another similar flare in 1989 "provoked geomagnetic storms that disrupted electric power transmission" and caused blackouts across the Canadian province of Quebec.