12. Tides are caused mainly by the _____ in the gravitational effect of the Moon on the near, middle, and far sides of the Earth. Hint: Refer to Figure 4.16 in the OpenStax Astronomy textbook. The water on the side of the Earth _ to the Moon experiences a stronger gravitational attraction to the Moon than does the solid Earth (which can be represented by a point at the center of the Earth), hence there is a tide on the side of the Earth closest to the Moon. There is also a high tide on the side of the Earth farthest from the Moon because the water is attracted to the Moon _ strongly than is the solid Earth, so the water there tends to bulge away from the Moon. Hence, most coastal locations on Earth experience __ high tides every 25 hours.

Word Bank for paragraph above: closest / difference / farthest / high / less / low / more /one / two / three. Answers will be used once; some answers will not be used.

The tide is the periodic change of the sea level produced mainly by the gravitational attraction forces that the Sun and the Moon exert on the Earth. This attraction is exercised over the entire planet, in its solid, liquid, and gaseous masses. The ellipsoid due to solar tides has the major axis directed towards the Sun. The ellipsoid due to lunar tides has the major axis directed towards the Moon. As the Moon revolves around the Earth, the major axes of the ellipsoids do not rotate at the same speed. With respect to the stars, the period of rotation of the solar ellipsoid is one year. The ellipsoid of the Moon is 27.32 days. The result is that the axes of the two ellipsoids get closer every 14,7652944 days. When the major axes of the two ellipsoids are aligned, the amplitude of the tides is maximum and they are called live tides. This happens in new moons and full moons. In contrast, when the major axis of each ellipsoid is aligned with the minor axis of the other, the amplitude of the tides is minimal. This happens in waning rooms and growing rooms. These tides are called dead tides or quadrature tides.