Well, putting astro
in front of any field means you possess superior, more advanced knowledge. An astro-sociologist, for example, pointlessly speculates about the cultures on many worlds, not just our own, and an astro-economist is completely wrong about more than one planet. And of course an astro-cosmotologist, which sounds technical, knows what kind of highlights and eye shadow goes with blue skin. Somehow a few instances of astro upgrading became accepted, and astro-biology would be one of them.