周しゅう天てん

noun

full scope of the heavens; 360 degrees; one full revolution of Earth

Astronomical term for the entire celestial sphere, a full circle, or one complete orbit of the Earth. Rare and technical.

• 周しゅう天てんは天てん球きゅうの全ぜん範はん囲いを指さす古ふるい天てん文もん学がくの用よう語ごだ。

  周天 is an old astronomical term referring to the full extent of the celestial sphere.

noun

twelve years; one full cycle of the Chinese calendar

Refers to a complete 12-year cycle of the Chinese zodiac. Rare and mainly historical or calendrical.

• 周しゅう天てんは十じゅう二に支しの一ひと巡めぐり、つまり十じゅう二に年ねんを意い味みすることもある。

  周天 can also mean one full cycle of the twelve zodiac signs, i.e., twelve years.