Here's why:

* Gravitational Pull: The moon's gravity pulls on the Earth's oceans, causing tides. The sun also exerts a gravitational pull, but it's weaker than the moon's.

* Alignment: When the sun, Earth, and moon are aligned (during new and full moons), their gravitational forces combine, resulting in higher high tides and lower low tides, called spring tides.

* Right Angles: During quarter moons, the sun and moon are at right angles to each other in relation to Earth. This means their gravitational forces are pulling at a 90-degree angle, partially canceling each other out.

* Result: The result is weaker tides, with lower high tides and higher low tides, known as neap tides.