What would be the rarest aurora seen in the sky?
This a really interesting question. I think I will try to give you two answers, depending upon just what you mean. In the auroral zone, where the aurora is most common, the rarest aurora seen is probably the corona. The reason is that the observer has to be located directly below an aurora that is composed of two or more very narrow arcs. In general, the rarest aurora would be an aurora seen at very low latitudes, say in Puerto Rico. This may occur once every solar cycle (11 years) or less. Also a rare aurora is a very red aurora covering the entire sky seen at mid-latitudes. The most famous one occurred back in 1958. Dr.
