Living near a star has its benefits but one has to face consequences too. Last week we witnessed a M9 class solar flare and an intense Coronal Mass Ejection (CME) hitting the Earth. CMEs are large volumes of charged particles ejected from the Sun’s Corona. Interaction of these charged particles with the atmosphere gives rise to spectacular auroras which can now be found floating around on youtube.
The strongest such event in recorded history the September 1-2 1859 Solar Flare also known as the Carrington event after the observer RC Carrington. Carrington was taking routine observations of sunspots when he came across this unusual event. The original report can be found here. As a result of this intense solar flare, the global telegraph network was disrupted. Charge flowing in the telegraph wire was large enough to have ignited telegraph paper.
A recent example of a much smaller event was the solar flare of March 1989 which left 6 million people in Canada without electricity for several hours. If such an event were to happen now, power grids will be disrupted and intense radiation can knock off satellites. The two bedrocks of modern life will be damaged (depending on the magnitude of the event) and it is hard to imagine the consequences of living without electricity and satellites. Our civilization is more susceptible to natural disasters than ever. But, unlike in case of previous solar events, we now have a much better understanding of the physics behind these event and we can now predict such occurrences in advance.
Other than the effects on technology, such events can have devastating effects on life. Charged particles blasted from the Sun ionize the Earth’s atmosphere which result in dissociation of nitrogen and oxygen in the atmosphere. A a result a multi step reaction in the stratosphere depletes the ozone layer. A depleted ozone layer gives way to harmful UV radiation which is well known to have carcinogenic effects. Such events could have affected life on our planet in the past. A detailed analysis by Brian Thomas and colleagues can be found here.
But should be worry about it? Observations of Sun-like stars have shown much stronger flares than the Carrington flare. However, we don’t know what is the frequency of such events. It is probably very low but more research needs to be done in order to know for sure.