X-Flares and Large Filaments / Magnetosphere Changes You Should Comment On
X-Flares and Large Filaments / Magnetosphere Changes You Should Comment On
To the casual observer, the Sun may appear calm and unchanging. However, the behaviour and energy output of our nearest star varies according to a cycle that lasts 11 years or so. This behaviour has been followed for centuries by counting the number of sunspots – dark regions that appear and disappear on the visible solar “surface.” The rise and fall in the number of sunspots – and the accompanying variations in solar activity – have attracted renewed attention recently as the Sun approaches a peak in its 11-year cycle. This interest has also been fuelled by spectacular images from spacecraft like the Solar and Heliospheric Observatory (SOHO).
However, as we have become ever more reliant on space-based technology, including the global positioning system (GPS) for navigation and re-mote monitoring, we have also become more vulnerable to the major disturbances that solar activity can trigger.
The events that occurred at the height of activity during the two previous solar cycles altered our perception of so-called space weather. Some of the largest fluxes of solar radiation ever detected were measured in August 1972, in between the two Apollo lunar landings of that year.
If the blasts had occurred while astronauts had been on the Moon, they would have received a potentially lethal dose of radiation. Instead, one of the major telecommunications lines in the US failed briefly, and satellites in the popular geosynchronous orbit some 40,000 km above the Earth were exposed to energetic particles from the Sun that affected their solar-cell power systems.
More recently, during a magnetic storm in March 1989, transformers at power stations in Canada were affected by a current surge that was induced by the changing magnetic fields at ground level. The surge led to power blackouts throughout Quebec that lasted for several hours, and the power company lost more than 21 500 megawatts of its production capacity. In addition, a transformer at a nuclear-power plant in New Jersey was damaged beyond repair as a result of the induced current.
Published on May 13, 2013
