There is widespread interest among discipline-based science education researchers toKeywords: Astronomy Education Research; Science Education Literature Review rogress in astronomy education research-heretofore referred to simply as AER-requires that we first understand the scope of what is known about teaching and learning astronomy content across diverse settings, and what is not. Unfortunately, AER is a broad scientific discipline in which the existing landscape is particularly difficult to comprehensively grasp. Unlike the field of traditional astronomy in which research is conducted nearly exclusively by individuals who hold the exclusive identities of "professional astronomers," AER is conducted by individuals representing a wide variety of academic settings and affiliations, including professional astronomers, astronomy education researchers, planetarium operators, cognitive scientists, psychologists, anthropologists, science educators, science education researchers, teacher educators, policy makers, museum educators, curriculum developers, outreach enthusiasts, and publishers (Slater, Slater, Heyer, & Bailey, 2015). These individuals most often present findings in research journals tightly related to their own professional fields, hindering knowledge transfer amongst communities of researchers and practitioners. Absent the ability to accurately describe the existing research landscape we often swirl in the vortex of our preconceptions, stymied in our efforts because we do not have a grasp on what we do and do not know, about the ways that humans currently and might possibly come to learn astronomical concepts.Isolation caused by disciplinary silos is magnified by other factors that drive AER toward domination by a few voices, from a few research settings, using a limited set of theoretical frameworks and methodologies. Works published as dissertations and thesis, in the pre-digital era, from lesser known journals coming from non-Western countries, or that are hidden behind paywalls are disadvantaged in their ability to influence the AER research agenda. Researchers from smaller institutions and from developing nations experience the greatest barriers to access these community resources