First of all, this is not a blog entry that focuses on the answer to that question. Rather, it is more of a "puzzlement" on the PERSON who would ask such a question.
So if someone asks you that question online, or if you read a question like that online, what would be your first reaction? I'll be honest, my first reaction was : why is this person THAT lazy?
Let me explain why my reaction was like that. If this was asked, say, 15, 20 years ago or more, then I would not have that reaction. I would try to spend time and clearly explain why aurora borealis is NOT caused by Cherenkov radiation. Now, it is not obvious why, of course, to anyone who isn't familiar with physics. So that is a perfectly valid question to ask! Nothing wrong with that.
But when asked in this day and age, one wonders why the person never googled for the answer before asking. Now, I'm not talking about the question popping up over some casual cocktail party where someone just remembered the question and decided to ask it. After all, with all the conveniences and ability to look up practically everything imaginable, there is no longer any excuse for NOT having, at least, some answers in something. It would be a different matter if someone has read something that he/she didn't understand, and want a clarification. But asking questions like "What is the mass of a photon?" or "What is quantum mechanics?" etc.. etc. that are really either very general or extremely available online is rather puzzling.
Learning is a very PERSONAL journey. It is your own self-realization and understanding. So whenever one likes it or not, one has to do one's own homework. It can't be shoveled into you. My point here is that, at least from my perspective, if I don't know something, I look it up FIRST. Typically, if it is way outside of my area of expertise, I will always encounter something that I don't quite understand. Even then, I will try to look up other resources and see if I can find something that that would explain it better. Only when that fails, I will try to seek help. In other words, I don't go around posting online the very first question that goes through my head without first trying on my own to find the answer. With all the information available on the web, there's no reason for that.
Unfortunately, with such easy access to various information, are people simply getting too lazy? It is now no longer sufficient that most of what we want to find is only a few clicks away without having to leave our computer. Those of us old enough to remember going to libraries and hunting through card catalogs to find either a book or a journal certainly would not understand such laziness. I have seen way too many instances of people, especially kids in school, whose attitude borders on some notion of ENTITLEMENT to be given the answers to any question that they may have. "I have an question, so give me the answer!". That isn't learning.
So, is aurora borealis caused by cherenkov radiation? One can easily satisfies oneself that it can't be simply via logic. Our atmosphere is bombarded by a lot of high energy charged particles, all over the earth. Yet, aurora borealis occurs predominantly at the earth's poles. If this is nothing more than cherenkov radiation, it would be common all over the world. Yet, we don't see that.
BTW, we do detect cherenkov radiation from high energy cosmic rays. That's what many of the detectors such as the Auger Observatory are doing. Clearly, no aurora borealis accompanied such detection.