Jupiter name is traditionally masculine but has also been used for girls in recent years. For instance, there were 136 newborn girls who were named Jupiter in the United States in 2022 and only 65 boys named Jupiter in the United States in the same year.
I didn't get notified that you replied...? Sorry. I also think Jupiter isn't a good name for girls. Jupiter Ann Weinstein? Jupiter Venus Smith? Who knows! Didn't Gwenith Paltrow name her daughter "Apple?"
They looked at it in the sky (with some kind of telescopes) and found it big considering that he's far from Earth, so until now, Jupiter is the "king" Of the planets in our solar system.