The synodic period is the time it takes for two orbiting bodies — like Earth and Mars — to return to the same relative alignment (as seen from one to the other), which is different from each body's own orbital period around the Sun..
The synodic period is the time it takes for two orbiting bodies — like Earth and Mars — to return to the same relative alignment (as seen from one to the other), which is different from each body's own orbital period around the Sun.
Earth (T1 = 365.25 days) and Mars (T2 = 687 days). Synodic Period = 1 / |1/365.25 − 1/687| ≈ 780 days — close to the real ~26-month interval between Mars oppositions.
The time for a body to return to the same position relative to the Sun and Earth as observed from Earth.
1/synodic period = 1/Earth's period − 1/other planet's period.
Earth's own motion means the apparent cycle observed differs from the planet's true orbital period.