Astrobiology is study of life outside earth; it includes the possibility of life on other planets, possibly around other suns.
But there hasn't been any EXTRATERRESTRIAL BIOLOGY found. All they have to study, is TERRESTRIAL BIOLOGY ?
Read the article I coped and pasted. Actually, astrologists look for extraterrestrial ecological areas that could harbor life. Also they study extremeophiles because of their ability to inhabit possible extraterrestrial type habitats.