Increased visibility and activity in the Aurora Borealis (Northern Lights) and the Aurora Australis (Southern Lights) are some of the more beautiful effects of solar flares on the Earth. There are though, very real and potentially catastrophic effects that can reach Earth in a matter of minutes following a solar flare.
The effects of a solar flare can hit our Earth head on in as little as 15 minutes from the time the flare itself occurs on the Sun. In January 2005 a solar flare released the highest concentration of protons ever directly measured, taking only 15 minutes to reach the Earth, travelling at a third of the speed of light. Astronauts had to seek shelter from the hazardous doses of radiation that were released, and the energized protons that can pass through the body causing biochemical damage.
A solar flare, or more precisely the solar wind or 'coronal mass ejection' of highly energised particles and protons that results, can affect our Earth in a number of ways.
Spacecraft are the first affected. Energy manifesting itself as hard x-rays can damage the electronics of spacecraft and satellites, and soft x-ray flux increases the ionization of the upper atmosphere which physically heats it, increasing the drag on low orbit satellites and leading to orbit decay.
Solar flares and their solar wind create geomagnetic storms. The solar wind pressure compresses Earth’s magnetosphere and the magnetic field interacts with our own, creating increased electrical current in the magnetosphere and ionosphere. In 1989, a geomagnetic storm actually induced ground currents and disrupted or knocked out power distribution in most of Quebec and caused the Aurora Borealis to be seen as far south as Texas.
Radiation released by solar flares and solar winds can affect humans too, although our atmosphere provides protection at ground level, astronauts can be affected as described above, and even aircraft flying at high altitudes can experience higher than normal radiation.
Growing evidence indicates that changes in the Earth's geomagnetic field can also physically affect stressed human and animal biological systems. Animals that are known to have internal biological compasses, in the form of magnetite in their bundled nerve cells, can also be affected. This includes animals such as dolphins and whales, and in particular, and most studied, which are homing pigeons. Because many pigeon races, that have ended in only a small percentage of birds returning home, have occurred during geomagnetic storms, some pigeon racers and handlers now ask for geomagnetic alerts and warnings before scheduling races.
The ionization of the atmosphere can interfere with many communications too, because they use the ionosphere to reflect radio signals over long distances. Short-wave broadcasts such as ground to air, ship to shore and amateur radio are disrupted frequently. Military early warning systems that detect missile and aircraft launches from the signals being bounced off the ionosphere can also be affected.
In our hi-tech times, perhaps most worryingly, damage to communications satellites can cause widespread disruption to satellite telephone, Internet, GPS (global positioning systems) and television and radio links. Geomagnetic storms can also hazardously increase current in old fashioned telephone and telegraph lines, and long distance undersea cables that are not fibre optic.
The scientific community are taking ever more interest in solar flares and solar winds and their effects on the many systems that our modern Earth relies upon.