The primary cause of tides on Earth is the gravitational interaction between the Earth, the Moon, and to a lesser extent, the Sun. The gravitational forces exerted by these celestial bodies create a tidal force that influences the oceans and bodies of water on our planet.
Although the Sun is much more massive than the Moon, it is the Moon that has the greater influence on Earth's tides. This is because the Moon is much closer to the Earth, resulting in a stronger gravitational pull on the Earth's oceans.
The gravitational force exerted by the Moon causes a bulge in the ocean on the side of the Earth facing the Moon. Simultaneously, a second bulge occurs on the opposite side of the Earth, which is due to the centrifugal force resulting from the Earth-Moon system's rotation. These bulges are referred to as tidal bulges.
As the Earth rotates within the gravitational field of the Moon, these tidal bulges move around the planet, resulting in two high tides and two low tides within a 24-hour period. The areas of the Earth experiencing high tide are located on the sides of the Earth facing and opposite to the Moon, while the areas in between experience low tide.
Although the Sun also exerts a gravitational force on the Earth, it is about 27 million times farther away from the Earth than the Moon. Therefore, its influence on tides is relatively weaker compared to the Moon. However, during certain alignments like during a new moon or full moon, when the Sun, Earth, and Moon are approximately in a line, the gravitational pull of the Sun combines with that of the Moon, resulting in higher high tides called spring tides or exceptionally low tides called neap tides.
In summary, while both the Moon and the Sun contribute to the tides on Earth, the Moon's proximity and its gravitational force have a more significant impact on the tides than the Sun.