The length of time it takes an orbiting object to make one complete trip around its primary body. The Earth’s orbital period around the Our parent star. The structure of Sun's interior is the result of the hydrostatic equilibrium between gravity and the pressure of the gas. The interior consists of three shells: the core, radiative region, and convective region. Image source: http://eclipse99.nasa.gov/pages/SunActiv.html. The core is the hot, dense central region in which the is 1 year and the Moon’s is one 27.3 days.
Mercury’s orbital period is ~88 days (closest to the Sun) and Neptune’s is ~165 years (farthest from the Sun).