I added an English linguistics degree to my main (physics education type) degree while I'm waiting to complete the high school teaching certification, which is so easy anyone can do it, but it so slow I figured I might as well just throw on something I'm interested in that only required a few classes I hadn't already taken as credit filler.

I teach low level astronomy classes for a university, help run telescopes at its observatory, and have done and presented some simple astronomy research there as well.

That's no hard thing, mind you. Anyone can do astronomy. Download a star map online, print it out, and start learning your stars and constellations. Once you do that, it takes a couple months, buy astronomical binoculars. Once you have exhausted your interest there, buy a computerized scope. You'll have the know how to run it. At that point, you can start doing astronomy research, albeit for free, by looking at variable stars and submitting data on the AAVSO webpage. Your data will be used for legitimate scientific papers. Maybe a year or two of casual observing and learning is needed.

The physics behind the astronomy is usually harder and lamer to learn. You'll need classes and mathematics skills, but it isn't needed.

If you're interested in English linguistics... That's very difficult to get into at a hobby level. There are some error filled pop linguistics books, and some podcasts about language history (historyofenglishpodcast.com, for example, is great), but by and large it's one of those things you really need training for, which sucks.

Being a fan of words, on the other hand, is easy. Read your unabridged dictionary. Really read it. Read the blogs and articles on dictionary websites. Buy some of those popular linguistics books and some books about words. You're pretty much there.