THE EARTH, GRAVITY, TIDES, AND ECLIPSES

CHAPTER 19

What causes night and day? – The spin of the earth on its axis.

The Earth moves through space in 2 major ways: An imaginary line that passes through Earth’s center and North and South poles is called an axis. Rotation- the spinning of a planet on its axis. (causes day and night)Revolution- The movement of one object around another. (the earth around the sun-its orbit)

SECTION 1 THE EARTH IN SPACE

Summer, Fall, Winter, Spring- seasonsWhat causes them?

How the sunlight hits the Earth’s surface http://www.brainpop.com/science/weather/seasons/

SEASONS

Earth has seasons because it is tilted as it revolvesaround the sun.

http://www.youtube.com/watch?v=DuiQvPLWziQ

Section 2 Gravity and Motion

4. Gravity is the force of attraction between two objects. The two factors that determine the strength of gravity are mass and distance.

5. What keeps the earth and other objects in orbit? – the combination of inertia and gravity.6. What is inertia? – the resistance to change in motion. (Newton’s 1st law of motion-an object will stay at rest and an object will stay in motion until acted on by another force)

https://www.youtube.com/watch?v=p_o4aY7xkXg (gravity in 1min)

https://www.youtube.com/watch?v=mezkHBPLZ4A (what is gravity?

https://www.youtube.com/watch?v=u6rbrFgudLg(inertia)

7. What is the difference between weight and mass? – Mass is the amount of matter in an object. Weight is the force of gravity on an object.

https://www.youtube.com/watch?v=SegMt7sa42EWhat is the difference between weight and mass?

Section 3 Phases, eclipses, and tides8. What causes the phases of the moon? – the changing relative positions the moon, Earth and sun.

9. What factor determines what phase of the moon you will see? How much of the sunlit side of the moon faces Earth.

https://www.youtube.com/watch?v=79M2lSVZiY4 (moon phases rap)

Eclipses10. Describe an eclipse- When the moon’s shadow hits earth or earth's shadow hits the moon, an eclipse occurs.11. Name the two types of eclipses- Solar and Lunar

12. Describe in detail a solar eclipse: When the moon passes directly between E and Sun blocking light and casting a shadow.13. Umbra- the darkest part of the moons shadow 14. Penumbra- the area of the shadow that is less dark than the umbra.

15. Describe a lunar eclipse: What the E passes between the sun and moon

Tides16. What are tides and how are the caused? The rise and fall of water due to gravity. Caused by the gravity of the sun and especially the moon.17. Why do you think it is important for people to know the tide cycles?

Bay of Fundy CanadaHighest tidal range in the world. (Extreme high and low)Oceanographers attribute it to tidal resonance. The time it takes a large wave to go from the mouth of the bay to the inner shore and back is practically the same as the time from one high tide to the next.