also: にちげつせいしん
noun
the sun, moon, and stars; heavenly bodies
A yojijukugo (four-character compound) referring collectively to the celestial bodies, often used in poetic or literary contexts.
日月星辰の運行は古代から人々の関心を集めてきた。
The movements of the sun, moon, and stars have fascinated people since ancient times.
天体 is the general modern term for 'celestial body', while 日月星辰 is a more literary, set phrase specifically listing the sun, moon, and stars.
A yojijukugo composed of 日 (sun), 月 (moon), 星 (star), and 辰 (celestial body/heavenly body). The exact historical origin is uncertain, but it follows a classical Chinese pattern for enumerating celestial phenomena.