im or her take one normal step toward the "Sun." The child furthest from the "Sun" takes one small step forward.
- What happened to the oceans? They moved apart around the "Earth," but the "oceans" nearest to and furthest from the "Sun" are still fairly close to "Earth."
- Can the children find two sides of "Earth" where there is high tide and low tide?
- How might the coastal areas change during a day with only the Sun creating tides? The difference between high and low tide would not be as extreme.
Facilitator's Note: The time of high tide changes each day because the Moon is moving around the Earth. If we had no Moon, the tide due to the Sun alone would occur at essentially the same time every day.
Regroup the children and discuss Earth’s tides — and how different it would be without the Moon's gravitational pull adding significantly to the height of the tides. Explain some of the effects of tides on marine life: Tides create tide pools along rocky shores and where many creatures breed, feed, and hunt. Other creatures thrive in places like harbors, bays, and mangroves where the tide exposes mud flats or tree roots. Tides create currents that mix the ocean, spreading nutrients and removing waste.
- Many people live far from the oceans. Why is the ocean important to everyone? The children may have many ideas. They may have heard how oceans cover most of Earth's surface (71%) and contains most of the planet's water (97%). They may have learned how oceans influence weather. Seafood — including types that live, hatch, breed, or hunt in areas exposed by tides — is available to people living inland.
- What would a Moon-less Earth would be like with smaller tides?
Allow the children time to illustrate the influence of smaller tides in their Without the Moon... 3 comic panels.
Studying the motions and gravitational pull of the Moon today helps scientists understand its influence on Earth today — and long ago. Scientists use computer models to help them understand the relationship between the Sun, Earth and Moon — just like the children used their own bodies! They want to know more about how the Moon's gravity has affected the Earth over their long history together. They use mathematics to describe how the masses, speeds, and directions of the Sun, Earth, and Moon interact in space; and the computer combines all of the factors together to show the overall effect. Mathematics and computers are tools for looking at the past, into the future, and considering what might have been!
Now that the children have modeled the Moon's gravity and its major influence on our oceans, invite them to explore further. Invite them to check out books and videos about the oceans, seashore animals, and tides and share them — and their new knowledge of the Moon's importance — with their families.
Invite everyone to return for the next program, Moon Mythbusters, where they will put their science skills to the test!
May 9, 2011