Whilst your theory is very attractive, eta, I don't think it holds up to close scrutiny. Look at it this way:

There seems general agreement on the "O" sound (pronounced "oh" as in "oh, dear!") but there are alternative views about the consonant that accompanies it.
So far, so good.

The questions is, which consonants can be easily mistaken for each other? If we agree that those who heard "n" were hearing more or less the right sound, then it follows that plausible alternatives are not going to be fricatives or sibillants (which cuts out "s" and "k" and "t",) and dental or alveolar sounds (like "d" and "t") (I think I've got the names right - Faldage will undoubtedly put us right if I haven't.)

Indeed, I think the most likely sound to be confused with a nasal sound like "n" are the labial sounds like "m", "p", "f" or "b".

"Mo" is not any sort of word, (unless coupled with "'Arf a - ", which is not the case here)
"Po" is a word, of course, but makes little sense when used in the imperative, as seems to be the case at hand.
"Fo" is generally connected to "Fee, Fi" and "Fum" and I cannot think of any use for the word by itself, even in a universal or celestial context.

Which leaves us with "Bo."

Do you think that someone (thing?) is playing games with Jupiter, hiding behind Cassiopea, perhaps, and then jumping out when Jupiter isn't expecting it?
Or is Jupiter learning the violin, and what we are hearing is the instructor correcting his technique?

It just goes to show how little we really know of the universe out there, doesn't it?