What are Solar Storms?

A Solar Storm is an event in which activity of the Sun interferes in the Earth's magnetic field. These types of storms can be quite harmful. They are caused by solar flares and coronal mass ejections that formed a "solar wind", that is a gust of charged particles which can impact into the Earth's magnetic field if it goes in this direction. The impact can generate a light show as a geomagnetic storm, and the storm can last for several days under the right conditions. 


http://www.wisegeek.com/what-is-a-solar-storm.htm