The sun, a glowing ball of hydrogen, helium, and massive magnetic fields 864,000 miles in diameter is composed of six layers; three make up the sun’s “body” and three make up its atmosphere. Starting at its center is the core; here, the fusion of hydrogen produces all the light and heat we get here on Earth, is about 86,000 miles in diameter, and occupies about 10 percent of the overall radius.
The next layer is the radiative zone, where the energy from the core moves outward towards the sun’s surface in the form of light through radiation; it makes up approximately 64 percent of the sun’s radius.
The last layer of the sun’s body is the convective zone, which is where the light from the radiative zone cools enough to turn into heat causing the plasma to bubble and rise towards the surface through convection. It makes up the last 26 percent of the sun’s body. The first layer of the atmosphere is the visible surface of the sun known as the photosphere and is approximately 250 miles wide. The next layer, the chromosphere, is approximately 1,300 miles wide. The sixth and final layer is the corona, which is composed of highly ionized gases; it is the glowing ring that we see around the sun during a solar eclipse. Since it radiates out in different distances and different levels of brightness, it does not have an actual outer limit like the other layers.
The gravity at the center of the sun, like in all stars, is incredibly strong, getting weaker as you move farther away from the core. Even though the core is only about 10 percent of its volume, it contains 40 percent of its mass. The weight of the remaining 60 percent of the mass pressing down on the core is what creates the pressure that keeps the temperature high in the core.
SOLAR FLARES AND OTHER STELLAR PHENOMENA
The combination of highly energized gases and plasma, coupled with the constantly moving and fluctuating magnetic fields, causes a number of phenomena on and above the sun’s surface. These phenomena are normally associated with active areas on the sun’s surface. The three phenomena covered here all form in or near the active areas.
Sunspots are cool spots on the sun’s surface caused by magnetic fields looping, which slows the convection currents that move heat to the Sun’s surface and makes it appear darker. The locations on the sun’s surface where sunspots form are called active areas. Sunspots do not pose any danger to us on Earth, but the events that do occur in or near them can.
Solar flares occur when the magnetic fields cross each other. Where the magnetic fields have opposite polarity, the solar flare is formed, bursting out into the corona. The frequency of flares is based on their timing in the 11-year solar cycle. When the cycle is at its maximum, several flares can be observed each day, at its minimum, there is normally only one per day. Solar flares release high amounts of energy in the form of gamma rays and X-rays that can travel to Earth in a matter of hours or days, depending on the actions of the solar wind.
Once the energy released gets to our atmosphere, it can affect satellite to ground communications, such a GPS signals and satellite television. They can cause long-lasting, high-level radiation storms in the upper atmosphere. This radiation can damage sensitive satellite electronics, and even injure astronauts if they are exposed to high levels of these kinds of radiation. The Earth’s atmosphere and its magnetic field which curves around the planet from pole to pole serves as a very effective shield against X-rays and gamma rays, but once the energy reaches the atmosphere, it can heat it, which can affect radio communications that travel at that level. Solar flares are classified in three levels based on their size and strength; X is the largest, M is the moderate size, and C is the smallest. In a report on a significant solar flare in 2011, NASA stated that, “X-class flares are the most powerful of all solar events that can trigger radio blackouts and long-lasting radiation storms, disturbing telecommunications and electric grids.”
Coronal mass ejections (CMEs) are giant globs of solar plasma and magnetic fields that are ejected from the sun’s corona and travelling away from the sun at tremendous speed and with tremendous energy. They occur when the strong magnetic fields that give structure to the corona get twisted and break, causing gaps. These gaps normally occur above sun spots. These breaks in the magnetic fields allow solar material, often in the range of billions of tons, to be released.
CMEs can cause similar damage as that found with solar flares but through a different mechanism. While the effect of solar flares is mainly in the upper atmosphere, a CME’s effect is felt at lower altitudes and at ground level. As the plasma of the CME reaches the atmosphere, it also affects the Earth’s magnetic fields, pushing against the field on the side facing the sun and compressing it. This also stretches out the field on the side facing away from the sun. This change in the magnetic field moves the auroras down into the middle latitudes where it is visible to more people. The CME, if large enough, can also cause reach ground level at the poles, which can cause significant increases in the ground current running through the Earth. This increase in the ground current can damage power lines and power transmission facilities. These are relatively short-term problems that either only last a number of hours or can be repaired in a matter of a few days or weeks, but the ground current can also burn out massive, high-voltage power transformers. These are not items that power utilities have spares for sitting around; they normally take years to replace and are often custom made.
Although most of us are prepared at the family level to handle a loss of electrical power, many do not realize how much we—and the economy—depend on the presence of a reliable and widespread source of electrical power. Without electricity, the computers that run businesses and utilities don’t work, cell phone towers don’t work, gas pumps and water pumps that run on electricity won’t work, refrigeration in homes and grocery stores doesn’t work unless someone had the foresight to have a natural gas backup in place, tractor trailers can’t get gas so they can’t make their deliveries, and so on.
Dr. Jack Hayes, the director of NOAAs National Weather Service put it well when he said, “The Space Weather Prediction Center is critical to our economy because each time we use a cell phone, check a GPS locator, turn on a light, or take an over-the-pole airplane flight, space weather could have an effect.”
HOW WE CAN DEFEND AGAINST IT
Most solar events affect us at the infrastructure level. Satellites that serve the military or other governmental purposes are already shielded from radiation and effects on their orbits can be changed by way of ground control. Power infrastructure on the ground is in the most peril as it is designed to be efficient, which also makes it more susceptible to the effects of large-scale solar radiation. Power utilities are putting some measures in place but progress is slow and outages are still a very real possibility should another X-class solar flare hit the Earth.
On the individual level, the major threat is from the electro-magnetic pulse (EMP) that comes in the form of the magnetic fields that accompany solar flares and coronal mass ejections. The best defense against that is shielding in the form of a Faraday cage, which will shield electronics from the pulse.
Prepare for a variety of scenarios. The electrical grid going down is just one of the many disaster scenarios we all prepare for by increasing our self-sufficiency.
In terms of preparations you can make, change how you live your life in case you have to do it without electricity for several months should the grid go down in your region and it takes a long time to bring it back up. Be able to generate your own electricity and be able to share it or trade your capabilities with your neighbors. Replace items like LED flashlights, alarm clocks, and telephones that have circuitry in them with simpler, non-electronic versions that will not be affected by the EMP.
For those items with circuitry that you do need, such as laptops or cameras or ebooks, make backups and place them in home-made Faraday cages. The same should be done with spares for the controllers for your car, solar panels, and anything else that requires a microprocessor to function. Then after the pulse has passed, you will be able to replace the electronics in those items that are most vital to you.
And lastly, you should prepare yourself like you would for any natural disaster that disrupted the power grid and the accompanying shortages of food, water, power, and all the things that won’t be found on the shelves of stores after a few weeks.
Solar weather events, like solar flares and coronal mass ejections, are not like other natural disasters. They do not come with several days advance warning, like hurricanes or tornadoes. At most they come with two or three day’s warning provided by solar monitoring systems based in satellites. The time to start preparing for this kind of event is now, rather than just before it happens, so think about what you want or need to do and make it happen.
FOR MORE INFORMATION
There are several online resources that explain solar weather and how to prepare for its effects. Take a look at