Nice thread! Last night, I grabbed the noise-cancelling headphones, threw it on Nighttime setting and spent hours listening. I can definitely tell the Earthlike, water, and ammonia worlds.
The galaxy map also has sounds, and I spent several hours listening to those too. I was wandering through a G and F star field, as this is where I've found most of my Earthlikes. If you go to the galaxy map and zoom in on your star, you'll hear what sounds like radio static. Moving the camera around, you can also hover over other nearby stars and they'll produce static too. Some static is high pitched, some low. And on certain stars, you'd hear what can be described as the feedback from a microphone. Again, some were mid-range, while other feedback shrieks were incredibly high pitched. Some were deep shrieks. These aren't faint - you'll hear them after a couple of seconds, but not all stars produce the feedback. A disclaimer - the same star won't always produce the feedback shriek each time. Sometimes, I'd have to pick several other stars, and then choose it again to get the shriek after a few seconds.
So, for those stars with a high feedback pitch, I found either water or ammonia worlds. But, I didn't get a lot of testing in, and I might have just been lucky stumbling into a good planetary instance. There's probably some organization to the star sounds and what is contained within those systems... or at least, I'm hoping that is the case. It'd be great to hover over a bunch of G stars, and pick which ones will produce water or ammonia worlds.
