Astronomy is considered by many to be a gateway science owing to its ability to inspire curiosity in everyone irrespective of age, culture, or general inclination towards science. Currently, where there is a global push to get more students engaged in Science, Technology, Engineering, and Mathematics, astronomy provides an invaluable conduit to achieve this shift. This paper highlights the results of a study which has reviewed the presence and extent to which astronomy has been incorporated into the school curriculum of the Organisation for Economic and Cooperative Development (OECD) member countries. In addition, two others strong in astronomy research, China and South Africa, are included together with the International Baccalaureate Diploma science curriculum. A total of 52 curricula from 37 countries were reviewed. The results reveal that astronomy and its related topics are prevalent in at least one grade in all curricula. Of the 52 curricula, 44 of them had astronomy-related topics in grade 6, 40 introduced astronomy-related topics in grade 1, whilst 14 had astronomy-related topics explicitly mentioned in all grades. At all year levels, celestial motion is the dominant content area; however, topics such as stars, physics, cosmology, and planetary science become much more frequent as a proportion towards the higher year levels. The most common keywords employed in the curricula related to basic astronomy concepts were the Earth, Sun, Moon, and stars, all with a high frequency of use. There is hardly any focus on Indigenous Astronomy or the role of prominent women astronomers. Relational textual analysis using Leximancer revealed that all the major concepts could be encompassed within two broad themes: Earth and Physics. Astronomy and Physics are often seen as different domains, with astronomy content being more facts based, than based on concepts.