Astral FirestormA massive coronal mass ejection took place on the surface of the sun on Monday, and these charged particles will be hitting the Earth throughout the day today. Because they can affect satellites, these solar storms can have an impact on communications on Earth, though today's storm is not predicted to do much damage. These particles also show up in the form of beautiful Northern lights (aka aurora borealis), so keep an eye out tonight.
Nasa's Goddard Space Weather Center predicted that the coronal mass ejection was moving at almost 2,200 km/s when it was due to reach Earth's magnetosphere - the magnetic envelope that surrounds our planet - on Tuesday at 1400 GMT (plus or minus 7 hours).
This can interfere with technology on Earth, such as electrical power grids, communications systems and satellites - including satellite navigation (or sat-nav) signals.
In 1972, a geomagnetic storm provoked by a solar flare knocked out long-distance telephone communication across the US state of Illinois.
And in 1989, another storm plunged six million people into darkness across the Canadian province of Quebec. (source)
Above is the 2005 flare (via Boingboing)