Astronomy classification is often overlooked in classification discourse. Its rarity and obscurity, especially within UK librarianship, suggests it is an underdeveloped strand of classification research and is possibly undervalued in modern librarianship. The purpose of this research is to investigate the suitability and practicalities of the discipline of astronomy adopting a subject-specific faceted classification scheme and to provide a provisional outline of a special faceted astronomy classification scheme. The research demonstrates that the application of universal schemes for astronomy classification had left the interdisciplinary subject ill catered for and outdated, making accurate classification difficult for specialist astronomy collections. A faceted approach to classification development is supported by two qualitative literature-based research methods: historical research into astronomy classification and an analytico-synthetic classification case study. The subsequent classification development is influenced through a pragmatic and scholarly-scientific approach and constructed by means of instruction from faceted classification guides by Vickery (1960) and Batley (2005), and faceted classification principles from Ranaganathan (1937). This research fills a gap within classification discourse on specialist interdisciplinary subjects, specifically within astronomy and demonstrates the best means for their classification. It provides a means of assessing further the value of faceted classification within astronomy librarianship.