Jupiter has the most moons of any planet in the solar system with 79 known moons, while Venus and Mercury have no moons. Mars has 2 moons, Saturn has 53 moons, Uranus has 27 moons, and Neptune has 14 moons. The Moon is Earth's only natural satellite and the fifth largest in the solar system. The phases of the Moon affect health, mood, and tides on Earth. Easter is a religious holiday linked to astronomy as it falls on the first Sunday after the first lunar charge after March 31 each year.