They spend the majority of their time working on research, although they quite often have other duties such as teaching, building instruments, or aiding in the operation of an observatory.
ðeɪ spˈɛnd ðə mədʒˈɔːɹᵻɾi ʌv ðɛɹ tˈaɪm wˈɜːkɪŋ ˌɔn ɹᵻsˈɜːtʃ, ɔːlðˈoʊ ðeɪ kwˈaɪt ˈɔfən hæv ˈʌðɚ dˈuːɾiz sˈʌtʃ ɐz tˈiːtʃɪŋ, bˈɪldɪŋ ˈɪnstɹəmənts, ɔːɹ ˈeɪdɪŋ ɪnðɪ ˌɑːpɚɹˈeɪʃən əvən əbzˈɜːvətˌoːɹi.