I don't really understand EMPs much, so bear with me.

If a large solar flare occurred that was pointed toward Earth, and it was severe enough to cause EMP problems to all our communications, etc, would the effects be only on the side of the Earth that was facing the sun at the time? Or would the effect "wash" all around the globe and affect the entire planet?

I'm sorry if this is a silly question, and I give you permission to laugh.

Sue

Perfectly reasonable. And the answer is largely, yes.

Anything on the night side, on the ground, should be ok unless it takes a hit through communications or power grids. So should a lot of the lower satellites on the night side. Probably- the higher your orbit, the higher your risks, although a low enough orbit has it's own risks as energized particles skip and skitter along the upper atmosphere making pretty colors in the sky.

The bigger question is, how long do the flares and the resulting pulse last- if it's long enough for you to come out of the Earth's shadow, and it's still strong enough, you're toast.

Hi Susan,

Actually that is one of the most difficult questions to answer as the whole issue is extremely complex.



Because the sun can give off X-ray bursts together with huge volumes of charged particles in whats called a corona mass ejection (a part of the sun corona) is blasted/ejected into space at high velocities. This corona mass ejection would then interact with whats called the earths magnetosphere. In these interactions the earth is modelled as a spherical magnet in a heterogeneous fluid of charged particles which can move at a range of different velocities and therefore energies. These interactions are very complex to model giving wakes and eddys behind the earth from the direction of flow i.e. the dark side of the earth. Essentially the charged particles (particle radiation) are swept or funneled into the earth at both the north and south poles through the polar cusps. This also has the effect of increasing the charged particles energy before the particles strike the earths atmosphere. When the particles hit the upper atmosphere they release energy in the form of light (aurora borealis) and generate an electric field which can distrupt the Electrical transmission circuits of the power grids (especially those nearer the earths poles). This occours mostly at northern latitudes but as the intensity and higher energies (i.e. higher velocities) of the charged particles increase the effect will be to move further down from the north and south poles but with lesser intensity.

During very violent solar storm activity it has been suggested that something called a plasmiod can form in the plasma sheet which can then be re-ejected back into the earth atmosphere on the dark side. An analogy would be the backward eddy from the wake behind a ship with a blunt stern. Of course it should be rememebered that the earth rotates once every 24 hours so the length of the corona mass ejector and it velocity of the ejector will have an effect also. The time of year will have an effect also because the angle of the earths poles varies throughout the year to the incident direction of the flow of charged particles.

X-ray bursts are not effected by the magnetosphere and this effect will effect only the sun lit side of the earth.

Therefore in theory a large and violent corona mass ejector could damage most of the world power grids (mostly based in the northern hemisphere) and satellite commuincations either on the light or dark side of the earth.

EMP weapons are slightly different in how they work (but use the same principle of generating compton electrons in the upper atmosphere called the ionosphere) as they rely on the extremely high bursts of locallised radiation interacting with the earths atmosphere which have very short time scales to produce a high electromagnetic pulse with a very short rise time to induce high currents in sensitive electronic equipment.

I'm certainly no expert on CME's but I do know that Quebec's power grid failure back in 1989, blamed on a powerful CME, occurred in the middle of the night. So, based on that, I would think, yes, a CME can also affect the night side of the Earth.

In Quebec's case, I suspect that it's location in more northern latitudes had something to do with its being knocked out of commision. However, with any CME powerful enough, I would think that higher latitudes near both poles, both day and night side, would be most at risk from the accumulation of charged plasma particles in the earth's magnetic fields.

My God! I have to agree with Bentirran.
In this case you have to deal with a massive amount of energy.
It is not an isolated event like a nuclear detonation - which, even if it seems large, is actually small on a cosmic scale.

Thanks, guys!

Sue

I remember that- we had a pretty aurora that night to. Northern Lights == EMP. Now that is a depressing thought.

Something to remember, as far as precautions are concerned, EMP is EMP, regardless of the source. Solar events just last longer.

I think that for the most part, -at least initially, -it would be effecting only the Sunward Facing side of the Earth, -at impact time. But depending on the Duration of the Flare Hit, -some of Earth's Night Side will rotate into the Damage. Also, Satellites above, will have far less "earth Shadow Effect", -than things down here on the ground. Also, and increasingly over time, --there should be some "Wind and Ocean Current Spreading Effects", as well.

Ouch Bentiran, I'll never will asked you for the time or you will tell me how to make a tic-toc hahahahaha good show and thanks.