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.
Relative to the stars, the sidereal period is the time it takes for a planet to complete one orbit. The orbit of a planet around the Sun measured with respect to the âfixed starsâ is used to determine the sidereal period. The sidereal period of the Earth is 365.25636 mean solar days, which is slightly longer than the tropical year (measured between successive vernal equinoxes) of 365.24219. In most calendar systems, the length of the year is taken to be 365 days, which is close to the Earthâs sidereal period. Leap years are added to reduce the amount of calendar drift between the observed dates of events (e.g. solstices and equinoxes) and their expected calendar dates. Planetary data: Sidereal Periods