This study examines the phenomenon of ilmu falak which is often considered different from astronomy. In fact, if we examine further, both are the same science. The narrowing of definitions occurred between the two, along with the long history of the two sciences. Until then, today's definition narrows the terminology of ilmu falak as practical astronomy that is used to help the needs of Muslims in worship. Then the polemic occurred when ilmu falak was entered as a major taught at several Islamic universities in Indonesia. Is the application a "tragedy" dichotomy of science, or is it the opposite, an effort to implement the paradigm of the unity of science itself? Based on the literary method using a phenomenological descriptive approach and a unitary science paradigm approach, the results of the study show that ilmu falak and astronomy are actually the same scientific unit. The narrowing of the definition of astronomy occurs, because of the long history of science. And ilmu falak approach as a major/course at several Islamic universities in Indonesia, is an implementation of the paradigm of integration of science itself, namely between astronomy and Islamic jurisprudence.