Naphtalene is an aromatic compound, something like two benzene glued together at one side.
How it can be produced?
Full-synthesis must be a bitch, however, you should know that partial burning of organic material in anaerobic conditions produces a lot of aromatic compounds.
You can find a lot of them in cigarette smoke and they are almost always carcinogenic, that's why cigarette is bad for your health.
So even though it is a fairly complex compound, it should be very easy to produce (just burn some stuff the right way).
And its large delocalized electron-system (i.e. aromatic ring) makes it quite stable too.
Which means, that it should have been found a long time ago.
The article says that there are a lot of known spectroscopic signatures that can be attributed to diffuse electron-systems, it's just they weren't as yet identified with known compounds.
Now, they managed to do it for some bands, and the result was the naphtalene cation.
The rest is told by alec.