Astrobiology is an interdisciplinary field that studies all life in the universe including extraterrestrial life and life on earth; it’s origin, evolution, and location of potentially habitable planets outside our solar system; adapting earthlings to life in outer space; and exploring the question of whether life exists on other planets besides Earth. (Check out this wikipedia article that puts it much more succinctly). Astrobiology is a real scientific field studied by real scientists.
Xenobiology is essentially the study of and search for alien life in the universe. It’s also a real scientific discipline, but it’s sometimes termed “a science in search of a subject,” because we currently haven’t found any convincing evidence of extraterrestrial life (here’s a really old 1981 paper on Xenobiology).
When I was at LTUE this February I attended a panel on using speculative xenobiology or considering evolutionary biology to make the flora and fauna of your story’s alien world richer, more interesting, and more consistent. The panel has a number of scientists on it that also happen to write fiction and the lecture was a super interesting discussion mix of straight-up biology, speculative anthropology, and speculative philosophical origins and purpose of life in the universe.
Writing Prompt: Brainstorming Xenobiology (GA)
For homework, read a couple of non-fiction books on evolutionary biology, anthropology, or environmental ecology to glean inspiration for the milieu of an alien world you’re going to use in your next story, including animal and plant life, cultures of sentient species/races, and so forth.
After brainstorming this out, come up with an interesting conflict for your main characters that involves dealing with hostile alien encounters (perhaps they’ve become stranded on an alien world and need to get back home; they’re trying to control an invasive species of alien life form or virus that is wiping out earth habitats; or there are secret challenges to settling an alien environment humans thought would be easy to colonize).