Let's be clear. There is no way, no how, in any way shape or form that Ferdinand Magellan is Jewish.
How can we be so sure?
It's pretty simple, actually. Y'see, it's been recently suggested (most notably in "Over the Edge of the World" by Laurence Bergreen) that Magellan's mother may have been Jewish. Perhaps.
Why? The old last-y name-y thing-y rears it's head. Magellan's mother was named Alda de Mesquita. Mesquita means mosque. Conversos (aka the Jews who were forced to change their names in order to hide the fact they were Jewish from the various religious purges that were the hip thing to do in 1400s Spain and Portugal) often took very religious, yet very non-Jewish names. Y'know, just to throw the scent off as much as possible (how successful these choices were considering that every very non-Jewish-named person is now immediately suspected of being Jewish is left undiscussed).
So... ummmm... there ya go? Magellan's mother had a very religious non-Jewish name and therefore was Jewish and therefore Mr. Circumnavigation was also Jewish? Color us a little circumspect about being that definitive.
Besides, you're honestly going to tell us that there's a Jewish mother out there that's going to let her son leave his home country, become a citizen of another, then rent a boat and disappear for five years to some Hashem-knows-where-verkochte island?
Yeah, no. We got this one.