Spin-orbit Resonance

State that a body is said to be in if its rotation period and its orbital periodThe length of time it takes an orbiting object to make one complete trip around its primary body. The Earth’s orbital period around the Sun 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 are related in a simple way.