This is another question I was recently asked at the library. How many moons does Jupiter have? I work on level 3, which has all the astronomy stuff. I usually visit the section because kids with bent glasses are looking for pictures of planets, just like I used to.
I thought the question would be completely straightforward, like the previous “How many calories are in a banana?, but it was not. Various sources, including Universe Today, Wikipedia (I don’t think Wikipedia is the demon most librarians make it out to be, and the external links section can be very useful), and more, I found answers from 47 to 64 to 63 and a handful of other answers.
There are various classifications spanning “official” and “unofficial” moons, and that accounts for some of the variety in the answers.
Ultimately I went with the answer 63 from Universe Today. UT is run by my friend Fraser Cain, and he has complete credibility with me when it comes to astronomy and space news.
He also suggests, in this article, that the most relevant question is not about how many moons Jupiter actually has, but how many of those moons you can actually see.
Learning is strength training for your brain.