What are your thoughts on [name_u]Jem[/name_u] [name_m]Jupiter[/name_m]?
I always love [name_m]Jupiter[/name_m]. Something about it is just lovely and a bit magical. What is the name [name_u]Jem[/name_u]? The sound of this combo is nice. 
Sounds like a super hero! And I mean that in a very good way.
Very quirky and cute but I couldn’t see it on a teenager or older.
I think it’s super cool, I can see [name_u]Jem[/name_u] on any age but I struggle with the whole combo ageing well. [name_u]Jem[/name_u] [name_m]Jupiter[/name_m] really does sound like a kick ass superhero.
I love both names and I do enjoy alliteration, but on the other hand I agree with some of the previous posters that it might be a tad bit too cartoon-like
Some suggestions: [name_u]Jem[/name_u] [name_m]Judah[/name_m], [name_u]Jem[/name_u] [name_m]Julian[/name_m], [name_u]Jem[/name_u] [name_m]Julius[/name_m], [name_u]Jem[/name_u] [name_m]Alistair[/name_m], [name_u]Jem[/name_u] [name_u]Demeter[/name_u], [name_u]Jem[/name_u] [name_m]Walter[/name_m], [name_u]Jem[/name_u] [name_m]Sylvester[/name_m], [name_u]Jem[/name_u] [name_u]Winter[/name_u]
[name_u]Jem[/name_u] is an old nickname for [name_u]James[/name_u], but I prefer it by itself.
Ditto the superhero comments. I bet any boy would love to have this name, and I can see it aging well, too.
I like it! But I named my daughter a double J cartoon/super hero sounding name also, so I’m a little biased probably :).
This is everything, what an amazing combo! 
It sounds cool in theory but is a bit much for me personally
Perhaps to get to the nickname:
[name_u]James[/name_u] [name_m]Jupiter[/name_m] nn [name_u]Jem[/name_u]
[name_u]Jameson[/name_u] [name_m]Jupiter[/name_m] [name_u]Jem[/name_u]
[name_m]Jeremiah[/name_m] [name_m]Jupiter[/name_m] nn [name_u]Jem[/name_u]
It sounds (almost) too cool for a real-life adult, however, I’d adore it for a children’s book character!
I personally think it would be hard to grow into. I cannot imagine hiring a lawyer or doctor with the name [name_u]Jem[/name_u] [name_m]Jupiter[/name_m]. It is darling for a little one but maybe give him a more formal first name ([name_u]James[/name_u] or [name_m]Jeremy[/name_m]?) so that if he chooses a more serious profession he can go by that? [name_m]Just[/name_m] a thought.
[name_m]Jupiter[/name_m]'s racial baggage makes me uncomfortable. I would look for another middle name.
I actually like it. Most people aren’t going to always see / hear the middle name, so they would just associate the kid and adult with [name_u]Jem[/name_u] more than [name_u]Jem[/name_u] [name_m]Jupiter[/name_m].
I think it’s a cute alliteration, for sure. To make it less cute, I can see [name_u]James[/name_u] [name_m]Jupiter[/name_m]. I love both! J.J. would probably be one of the possible nns… and that I’m not too sure about lol.
Eh? I had to do a quick google to see what you were talking about. [name_m]Jupiter[/name_m] is ancient, going back to [name_m]Roman[/name_m] mythology, meaning the supreme god and father. The planet itself was called Marduk by the Babylonians and [name_m]Jupiter[/name_m] even by the ancient Romans who could view the planet with their naked eye. I’m guessing you’re referring to [name_u]Poe[/name_u]'s short story from 1843, “The [name_m]Gold[/name_m]-Bug”. I can’t find other references.
I’ve never heard of it having any racial baggage, would you mind explaining that?
[name_u]Love[/name_u] superhero/supervillian-esque names. I like it!
I absolutely love it! I think it’s so cool, and I agree with all of the superhero comments. Definitely think any boy would love to have it as a name, also think [name_u]Jem[/name_u] is just the sweetest.
[name_m]Jupiter[/name_m] was a popular name for male slaves in the US South. That connotation remains strong where I live, so seeing the name paired with [name_u]Jem[/name_u] (which I connect to [name_f]Jemima[/name_f] as well as [name_u]James[/name_u]) was a bit startling. Not something I would be comfortable with, but again, that’s me. [name_m]Just[/name_m] realized the OP is from the UK though. I suppose [name_m]Jupiter[/name_m] is more eccentric aristocrat vibe there?
It’s not a name I’ve ever came across, I’m just a bit of an astronomy geek. I had never head that before though, but I’ll bear it in mind. I don’t intend on having children anyway, so it entirely hypothetical.