Since the earth is rotating while this is happening, two tides occur each day. Isaac Newton was the first person to explain tides scientifically. For information on the moon, click here . They occur when the Earth, the Sun , and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides.
Spring tides occur during the full moon and the new moon.
The eccentricity of the orbit of the moon in this illustration is greatly exaggerated. The Proxigean Spring Tide is a rare, unusually high tide. The proxigean spring tide occurs at most once every 1.5 years . Neap Tides Neap tides are especially weak tides. Neap tides occur during quarter moons.