Final answer:
The tidal effect of the sun is less than that of the moon, but it still contributes to Earth's tides. When the moon and sun are aligned, their tidal forces reinforce each other, creating higher tides called spring tides. When the moon is at quarter phases, the sun's tidal forces partially cancel out the moon's, resulting in lower tides called neap tides.
Step-by-step explanation:
The tidal effects of the moon and the sun can be compared in terms of their strength and influence on Earth's tides. While the sun exerts a gravitational force on Earth that is nearly 200 times stronger than the moon's force, the tidal effect of the sun is less than that of the moon.
The moon's tidal force is greater because the fractional change in distance from the near side to the far side is much greater for the moon compared to the sun.
The actual tides we experience on Earth are a combination of the larger effect of the moon and the smaller effect of the sun.
When the moon and sun are lined up (at new moon or full moon), their tidal forces reinforce each other, resulting in higher tides called spring tides. When the moon is at first quarter or last quarter (at right angles to the sun), the sun's tidal forces partially cancel out the moon's, resulting in lower tides called neap tides.