synodic period



  • A period of time measured with respect to the Earth. Thus a synodic month is the period of 29.53 days in which the Moon makes a complete orbit of the Earth from New Moon to New Moon as seen by an observer on the Earth, allowing for the Earth’s rotation around the Sun. A planet’s synodic period is the time it takes to return to the same position – such as opposition or conjunction – with respect to the Earth, allowing for the orbital movement of each around the Sun.