Planets get their names from a variety of sources. Sometimes it's the discoverer or colonizer of the planet. Sometimes the planet grows a name over thousands of years of culture and language change. Sometimes politics gets involved, and the planet's name is changed for any of a variety of reasons.
When a discoverer names a planet, it may be based off of some interesting environmental feature, or maybe a famous person's name. Colonizers are similar.
Aurora (the Masquerader world) was named by its four founding corporations when they colonized and subsidized the partial terraforming of the world. It was named “Aurora” partially because it has amazing auroras (as does it's parent gas giant, the source of the magnetic field that generates those auroras), and partially because it is a nice happy sounding name that the marketing departments liked.
Tower (the Mechanican world) had some other name when it was first colonized. At the time, it was a relatively inhospitable rock (scrubland and desert) with deep rifts and valleys crisscrossing its surface. Since then, the mechanicans built huge cities clinging to the canyon walls. Their buildings towered over the river valleys, like giant monoliths, with spindly bridges weaving over the voids. The people decided that the old name was no longer apt, and decided to name the world “Tower” after their great metropolises.
I've discussed Overworld in the Cargo Cult thread, but it's worth repeating. Cargo Cults especially, name their worlds after generations of being by themselves. They stop thinking of their planet as just one colonizable world, and start thinking of it as the entire universe (or the relevant parts of it). Humanity named Earth… earth. Dirt. Cargo Cults come up with similar names for their worlds, based on what they think they are made of, or where they think it lies in their cosmology.
The names from my campaign that I remember offhand:
Mechanican: Tower, Wrench, Grid-7
Cargo Cult (now Tao / Old Worlder): Overworld
Stardweller: !G'niss (note: I don't think that Stardwellers normally have worlds in cannon)
Independent: Than (pronounced “Tane”).
Spacer (ship): Rotor (taken from an Asimov story)
Stored: Server Violet (for the analog-space server world; the digital worlds have their own names)
I see the Union as choosing pleasant names. Somewhere you might want to settle down and have a family. Good, wholesome, happy places.
I went techno-industrial with the Mechanicans. You really can't give a planet a serial number and expect people to take you seriously.
One question is whether you show the names translated, or in their parent language. The Stored tend towards Roman or Greek names, so they'd have Roman or Greek planet names. But when you're speaking in the Stored language, you may use their translation instead.
For GMs at least, a planet's name is best thought through carefully, and not just taken off of a pre-generated list (although sometimes there's need for a quick name). It's like naming an NPC. The name should reflect the character of the world, or its history. Players are going to be using it a lot, after all.