Is it possible to predict the appearance of auroras

astronomymagnetic fieldsplasma-physicssolar-windsun

Yesterday I saw online a lot of people seeing auroras both in the North and in the South of the globe. Unfortunately, I wasn't one of these people, and this got me curious about how much we can predict solar activity and the appearance of auroras on Earth. For example, I know we can make accurate predictions of eclipses, and weather forecasts on Earth are very common (within limitations).

In short, can we predict the appearance of auroras on Earth? If so, how good are these predictions?

Best Answer

Approximately yes, as follows.

Ham radio guys monitor solar activity closely because of the effects that it has on radio communications on earth. In this context, large numbers of sunspots are well-correlated with favorable conditions on earth for long-distance radio contacts- and the connecting mechanism is that large numbers of sunspots are correlated with the occurrence of mass ejections of charged particles from the sun. Those charged particles energize the layers of the atmosphere responsible for deflecting radio beams back to earth, thereby allowing them to carom back and forth between the earth's surface and the ionosphere and thereby circle the globe.

So you can estimate the prevalence of intense auroral activity with sunspot count.

That said, we are now at the maximum in the current 11-year sunspot cycle, which makes the coronal mass ejection responsible for last night's aurora an usual event, and demonstrates the utility of predicting auroras on the basis of sunspot count.

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