What impact do solar flares have on human activities?
Solar flares produce high energy particles and radiation that are dangerous to living organisms. However, at the surface of the Earth we are well protected from the effects of solar flares and other solar activity by the Earth’s magnetic field and atmosphere. The most dangerous emissions from flares are energetic charged particles (primarily high-energy protons) and electromagnetic radiation(primarily x-rays).
The x-rays from flares are stopped by our atmosphere well above the Earth’s surface. They do disturb the Earth’s ionosphere, however, which in turn disturbs some radio communications. Along with energetic ultraviolet radiation, they heat the Earth’s outer atmosphere, causing it to expand. This increases the drag on Earth-orbiting satellites, reducing their lifetime in orbit. Also, both intense radio emission from flares and these changes in the atmosphere can degrade the precision of Global Positioning System (GPS) measurements.
The most serious effects on human activity occur during major geomagnetic storms. It is now understood that the major geomagnetic storms are induced by coronal mass ejections (CMEs). Coronal mass ejections are usually associated with flares, but sometimes no flare is observed when they occur. Like flares, CMEs are more frequent during the active phase of the Sun’s approximately 11 year cycle. The last maximum in solar activity was in the year 2000. The next maximum was on 2013.
One serious problem that can occur during a geomagnetic storm is damage to Earth-orbiting satellites, especially those in high,geosynchronous orbits. Communications satellites are generally in these high orbits. Either the satellite becomes highly charged during the storm and a component is damaged by the high current that discharges into the satellite, or a component is damaged by high-energy particles that penetrate the satellite. We are not able to predict when and where a satellite in a high orbit may be damaged during a geomagnetic storm.
We can do nothing to stop a solar storm. All we can do is to predict them well before and get prepared for it.