0kay, I love this stuff so I am glad this thread was made. I am going to give my 2 cents with some help from some of the books I have read. Bare with me.....this might be lengthy.
Here we go......
Our government has expressed a great deal of concern over the nation's vulnerability to an EMP attack. The "EMP Commission" was formed to study the impact of the threat as well as propose recommendations to help our nation better prepare. An EMP (Electromagnetic Pulse) is an intense, broadband burst of electromagnetic energy. It can be a result of many things, including electrostatic discharge, lightning, a nuclear explosion, or specialized weapons. Of these sources, the EMP that results from a nuclear explosion has the greatest potential to cause widespread damage to our country. When people discuss an EMP attack, they are almost always referring to one that is a result of a high-altitude nuclear detonation. An EMP from any of these sources would result in strong electromagnetic fields. Fortunately, most pulses are short-lived and do not harm people or animals. The real threat from an EMP is its ability to disrupt, damage, and destroy electronic hardware. Affected systems could include the electrical power grid, cellular and wired communication systems, the internet, personal electronics, agricultural systems, airplanes, gas pumps, satellites, water purification plants, generators, automobile electronics, and nearly every other type of modern electronic device. A disruption like this would crush our economy and seriously degrade critical infrastructures, including: power, telecommunications, financial, petroleum and natural gas, transportation, food, water, emergency services, space operations, and government. SHTF is an understatement!
Now, for those of you who give a crap, lets talk about the Sun.......
The Sun experiences a periodic cycle in which it oscillates between being more and less active. During the more active times, sun spot activity increases, leading to more solar flares and coronal mass ejections. Predictions and history both agree that solar emissions are capable of disrupting radio communications and, more important, damaging our electrical power grid. The topic of solar disturbances is particularly timely given that the next solar maximum is expected to occur in 2012 or 2013. Now, unlike an EMP attack, whose likelihood is dependent on particular geopolitical events and the capabilities of our enemies, solar events that disrupt activity on Earth are an absolute certainty. It is only a question of their timing and severity, neither of which can be accurately predicted. Solar storms bring with them a wide array of threats, including radiation poisoning to humans in space or at high altitudes, disruption of communications and navigation systems, dangerous high voltages on pipelines, upsets to satellites, and destructive currents to electrical grids around the world. Fortunately, these currents are very low-frequency and do not couple well into small electronic systems, such as radios, cell phones, computers, automobiles, or airplanes.
Take what you want from this. I am not saying that either of these is going to happen in our lifetime. This is just a topic that has interested me for quite some time and what I have shared is just some of the information I have learned along the way.
Just remember, Nobody prepares to fail, they just fail to prepare.