Hence my having stressed lexicality... scope. If you are in the neighborhood of london, england, you can just say 'london' and people can presume with almost complete accuracy that you mean the one nearby. There are, however, probably like 20 londons in the USA... Now... a star light ours (Sol) is not remarkable at all. It's a dim, boring little star amidst a sea of hundreds of billions of stars amidst a sea of tens of trillions of seas of suns. It's only slightly less podunk than its neighbors, but dwarfed in long distance visibility by sirius and even more so by vega and arcturus in our immediate vicinity. That said, as a TERM, sol(ar) would be super useful in describing suns that would appeal to us in any given neighborhood... and to call a world 'terran' would be descriptive as well... so the names, as we do already on earth, are likely to be used over and over and over and over should we ever span galactic. If you're in this neck of the woods, then you could probably just say 'terra' and, as with the City of London, most anyone would know to which of the tens of thousands of planets in the vicinity you are referring to... but if you're traveling here from thousands of light years away, then you'll have flown passed dozens of planets the pilgrims on which would like to be able to name in homage to or for descriptive similarity the world of their origins. So it just makes sense, if you can get around out there, that you'd do exactly what we do here on earth... reusing names and referencing their 'depth of name' based on the scope of your current conversation. Orionia (arm) Arcturum (region) Sol (star) Terra (planet) Luna (moon) v. ??? (arm) Bellatrixum (area) Aria (star) Ares (planet) Terra (moon). There are lots of names yet to be used for planets.... but there are far too many out there not to be repeated thousands of times over.