περιστροφή

of a planet, star or of the cosmos

Θερινὸς δὲ τροπικὸς κύκλος ἐστὶν ὁ βορειότατος τῶν ὑπὸ τοῦ ἡλίου γραφομένων κύκλων κατὰ τὴν τοῦ κόσμου γινομένην περιστροφήν, ἐφ’ οὗ γενόμενος ὁ ἥλιος τὴν θερινὴν τροπὴν ποιεῖται, ἐν ῇ μεγίστη μὲν πασῶν τῶν ἐν τῷ ἐνιαυτῷ ἡμέρα, ἐλαχίστη δὲ ἡ νύξ γίνεται.

‘The summer tropic is the northernmost of the circles described by the sun during the rotation that the cosmos is performing, on which the sun, when it is on it, makes the summer solstice, on which [the] longest day of all the [days] in the year and the shortest night fall.’