Solar flares occur naturally on the sun. Large flares erupt from the sun and strike the earth from time to time and usually pose no threat to live here. Intensity of the sun storms and flares occur in patterns lasting about 11 years. The sun is entering a very active period which is expected to peak sometime in 2013.
There are two stages to the flare. The first stage is the radiation stage and it hits the earth within minutes of leaving the sun. Our atmosphere protects us from most of the effects of this stage. The second stage which is a burst of electrons reaches the earth days after the leaving the sun and NASA can usually detect and predict these waves.
In 1859, the largest flare ever recorded erupted from the sun and hit the earth. This resulted in the disruption of telegraph equipment for weeks. Considering how crude telegraph equipment is compared to today’s electronics, imagine the impact on today’s sophisticated equipment. Other than the disruption of the telegraph equipment no one was aware that it occurred since it is harmless to humans.
The atmosphere gives some protection from solar flares but not massive ones and the satellites orbiting the earth are vulnerable to a direct hit.
Consider the possibilities of a massive solar flare hitting the earth similar to the solar storm of 1859. It could disable communication satellites, short out the electric grid, and disrupt electronic equipment including computers, radios, etc.
Most likely, the entire planet will not be impacted with the exception of portions that depend on the satellites but large regions of terrestrial power grids and electronics could be burned up.
Such a hit could destroy transformers in over half of the United States. It would take months or even a year or more to restore the electrical power. Cell phone usage should only encounter a temporary disruption during the actual hit but cell phone and other communications would most likely be disrupted for a longer period if the power grid was damaged.
Suppose this happened. You would survive as it would not be life threatening but you would be put back immediately into the 1800′s where you would have no electrical power, communications, running water, and within a few days no fuel for your car, and the store shelves would be empty.
Most recently, on June 7, 2011 we encountered a medium solar flare.