Astronomy/Naming Conventions for Discovered Planets
When a new planet is discovered, who decides what to name it, and how is it named?
Is it normal to use the discoverer's name? Is it common to name it after the star it orbits or after the name of the system it resides in, perhaps appending a number to it?
If a planet is special in some way (not just your standard giant rock, or giant rock + lots of gas), do they get special names?
My ultimate purpose in asking all the above (though I'm curious about all that too!) is this: If we were to discover an earth-like planet with life, be that life sentient or not, what would we name it? Has there ever been any discussion of this? If sentient life (with a language that humans can approximate) resides there, would we just use their name for it?
I am assuming that an earth-like planet that can sustain life would be a HUGE discovery, and when it hits the media, there'd be some carefully-picked name to go along with it.
By international convention many centuries ago, only the IAU (International Astronomical Union) has the authority and responsibility to name EVERYTHING... stars, galaxies, planets, moons, nebulae, asteroids, even planetary and lunar/satellite surface features! (So never buy a star name as it will NOT be recognized by the astronomical community)! It has to be that way, otherwise sheer chaos would ensue for both astronomers and star chart makers.
(Could you imagine if the public could "purchase" a town name or even a street name for your state or town... it would be utter chaos for the inhabitants and visitors with maps changing daily! Maps and charts would have to be drawn up for a state or town almost DAILY!!)
Thus the need for convention.
The IAU even has the authority to name new comets, however in that case (with their permission) discoverers of new comets are "allowed" to give a new comet their own last name, simply conforming to an old tradition which the IAU upholds.
To your question... all the major Solar System planets have been found, from Mercury to Neptune and there are no more... a major would have long since been discovered either photographically or gravitationally, or both.
Planets of extra-solar stars are named by a lower case letter, for instance star 51 Pegasi's planet was named 51 Pegasi b and was the first extra-solar planet discovered. Even if that planet was eventually found to be Earth-like with humanoids, it would still, by convention, be called 51 Pegasi b. Of course, since some stars have both an astronomical name and a "common" name... (Alpha Scorpii is also Antares, Omicron Ceti is also Mira, Alpha Ursae Minoris is also Polaris with even a nickname, the North Star or the Pole Star, etc)... I'm sure some form of "common" name would evolve for that particular planet, but again with the IAU's...
concurrence. So, YES... there are conventions in place for EVERYTHING out there.
There HAS to be.
Discoverers may submit their own idea but the IAU has to approve it.
Recall that Galileo wanted to name the 4 moons of Jupiter, the "Medici stars" after his patron, and this was refused as they became Io, Europa, Ganymede, and Callisto.
Even William Herschel in 1781 wanted to name the 7th planet Georgius (or something like that) after his King George, and even he was refused... the planet was officially called Uranus, by mythical god convention for Solar System planets! So even some BIG names in astronomy... have been rebuffed and over-ruled by the IAU for convention sake.
So that's the way it HAS to work, otherwise utter chaos would occur.
Hope that helps,