Learn more by clicking the Google or Facebook button below. Population Demographics for Tonasket, Washington in 2016 and 2017. Other Counties and Cities in Washington.
Sidereal Period versus Synodic Period. 1  Measuring the motion of the Moon around the Earth relative to the distant stars leads us to what is called the sidereal period. 2  Measuring the motion of the Moon around the Earth relative to the Sun leads us to what is called the synodic (pronounced si-nod-ik) period.
Sidereal Period versus Synodic Period Measuring the motion of the Moon around the Earth relative to the distant stars leads us to what is called the sidereal period. The sidereal period is the time required for a celestial body within our solar system to complete one revolution with respect to the fixed starsâ¹i.e., as observed from some fixed point outside the system. The sidereal period of the Moon is the time needed for it to return to the same position against the background of stars. The Moon appears to move completely around the celestial sphere once in about 27.3 days as observed from the Earth. This is called a sidereal month. It represents the orbital period of the Moon around the Earth. Measuring the motion of the Moon around the Earth relative to the Sun leads us to what is called the synodic (pronounced si-nod-ik) period.