noun
Technical term in astronomy for the path of a celestial body or spacecraft around another body.
人工衛星は地球の周回軌道に乗っている。
The artificial satellite is in orbit around the Earth.
軌道 is a broader term for any track or path, including railways and trajectories, while 周回軌道 specifically refers to a closed orbital path in astronomy.
Compound of 周回 (shūkai, 'circulation' or 'going around') and 軌道 (kidō, 'orbit' or 'track'). The exact historical derivation is uncertain; the spelling is conventionally associated with the astronomical meaning.