恒こう星せい天てん

noun

sphere of fixed stars

Historical astronomical term from the Ptolemaic system; refers to the outermost celestial sphere where the fixed stars were thought to be embedded. Rare in modern usage, mainly encountered in historical or academic contexts.

• プトレマイオスの宇う宙ちゅう論ろんでは、恒こう星せい天てんは宇う宙ちゅうの最さい外がい層そうに位い置ちしていた。

  In Ptolemaic cosmology, the sphere of fixed stars was located at the outermost layer of the universe.