Tolkien’s use of specific stars and constellations within the legendarium has been well-studied. There remain two related questions to be tackled: firstly, why did Tolkien use these specific real-world stars and constellations, and what was behind the seemingly sudden expansion of the celestial population in the legendarium in 1951? Given his well-demonstrated interest in and knowledge of astronomy, Biblical passages that describe the heavens may have piqued his interest and may have influenced his choices of astronomical references in creating Middle-earth. Popularized works published during Tolkien’s youth on the astronomy of the Old Testament may have also played a role in shaping his opinion of these constellations. His final phase of constellation formation (circa 1951) may be related to his work on the Jerusalem Bible.
"Who Maketh Morwinyon, and Menelmacar, and Remmirath, and the Inner Parts of the South (Where the Stars are Strange): Tolkien’s Astronomical Choices and the Books of Job and Amos,"
Journal of Tolkien Research: Vol. 13:
2, Article 2.
Available at: https://scholar.valpo.edu/journaloftolkienresearch/vol13/iss2/2