1. Chapter 24.3, The Moon, Sun and Tides

2. Objectives Explain the nature of Earth’s tides Explain the sun and moon’s effect on Earth’s tides Explain the interaction of the sun, moon, and Earth

3. Tides are the periodic rise and fall of the ocean surface due to the gravitational pulls of the moon and sun. The highest point of a tide on the shore is high tide. The lowest point of a tide on the shore is low tide. When the moon is new or full, tides rise higher than normal. Tides are lower than normal during the time of a quarter moon. Source:https://pixabay.com/sv/m%C3%A5nen-himmel-natthimlen-263015/

4. Gravity is stronger when objects are closer together. The moon pulls the water on the side of Earth nearest it more strongly than it pulls on Earth itself (Direct high tide). At the same time on the other side of Earth opposite the moon, an indirect high tide occurs because the moon pulls more strongly on Earth’s center than it pulls on the water on the far side of the planet, leaving a bulge of water behind. The Moon and Tides

5. High Tides and Low Tides Source: https://commons.wikimedia.org/wiki/File:Tide_diagram.png These bulges on opposite sides of Earth pull water away from the areas that lie between the two high tides. These areas experience low tides.

6. Source:https://commons.wikimedia.org/wiki/File:Bay_of_Fundy.jpg

7. Because the moon moves around the Earth, the bulges of oceanic water also move around our planet over the 29 days that make up the lunar month. The moon rises about 50 minutes later each day and, as a result of this action, so do the tides of water on Earth.

8. The sun’s tide making effect is only about half that of the moon, because it is much further away from Earth than the moon. When the sun is aligned with the Earth and moon, the sun’s entire tide making effect is added to the moon’s. This alignment of the moon, the sun,and the Earth occurs at the times of the new and the full moons The Sun’s Effects on Tides

9. Spring Tides During these times, high tides are especially high, and the low tides are especially low These tides occur twice a month and are called spring tides "Hhttps://commons.wikimedia.org/wiki/File:High_ tide_sun_moon_same_side_beginning.png

10. At quarter phases, the moon and sun are not in line with the Earth. This results in smaller high tides and larger low tides These tides occur twice a month and are called neap tides The Sun’s Effects on Tides

11. When the moon is at perigee, the closest point to Earth in its orbit, the tidal effect is greater, especially if the perigee occurs during the new or full moon phases If the moon is at apogee, its farthest point from Earth, the tidal effect is less extreme The Moon’s Effects on the Tides

13. The sun’s complete tide-making effect only occurs when it is aligned with Earth and the moon? Question: True or False

14. Take one minute to discuss this question with your neighbor. Have EVIDENCE to back up your claims. Do the tides vary with the seasons?

15. https://en.wikipedia.org/wiki/Tide#/media/File:Tide_schemat ic.svg Source for previous slide: