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The Moon & Tides (77). Tides. Moon and sun contribute to the ocean’s tides. Gravity pulls the ocean water slightly & causes it to bulge out toward the moon. Opposite side of bulge also slightly bulges (due to earth’s rotation). This is where high tide occurs. Types of Tides.
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Tides • Moon and sun contribute to the ocean’s tides. • Gravity pulls the ocean water slightly & causes it to bulge out toward the moon. • Opposite side of bulge also slightly bulges (due to earth’s rotation). • This is where high tide occurs.
Types of Tides • High high (spring) tide: new and full moons, the moon and sun pull in similar directions (higher than normal tides). • High tide: side facing the moon (or directly opposite). • Low tide: side facing the sun (or directly opposite). • Low low (neap) tide: 1st and 3rd quarter moons, sun and moon pull in opposite directions (lower than normal tides).
Result of Tides • Water moving because of tides slows the earth’s rotation - 0.0015s/100years (days are getting longer). • Estimated that 900 million years ago the earth had a 18 hour day.
Future of the Earth and Moon • Earth also pulls on the moon. • Why the moon keeps the same side facing the earth. • Over time the moon’s orbit is growing & moves away ~4 cm/yr. • Measured by lasers.
Moon & Tides Diagram (76) • Draw 4 pictures of the earth, moon and sun showing when we have the 2 spring tides and the 2 neap tides every month. • Indicate the moon phase in each of the 4 pictures. • Answer the following questions in complete sentences: • Explain why the earth has tides. • Explain what the tides are doing to the Earth’s rotation.