This study examines whether an institution's research resources affect its centrality and relationships in international collaboration among 606 astronomical institutions worldwide. The findings support our theoretical hypotheses that an institution's research resources are positively related to its central position in the network. Astronomical institutions with superior resources, such as being equipped with international observational facilities and having substantial research manpower, tend to have more foreign partners (high degree centrality) and play an influential role (high betweenness centrality) in the international collaboration network. An institution becomes more and more active in international collaborations as its research population expands. In terms of the relationship, which is captured by an actor institution's co‐authorship preference for each partner in the network, the effect of research resources is not as significant as expected. We found that astronomical institutions are not necessarily preferentially co‐authoring with partners that have better research resources. In addition, this study indicates that geographic closeness (or “geographic proximity”) largely affects the occurrence of international collaboration. The investigated institutions apparently prefer partners from neighboring countries. This finding gives an indication of the phenomenon of “regional homophily” in the international collaboration network.