THE EARTH, GRAVITY, TIDES, AND ECLIPSES

CHAPTER 19 By Mr. Jhupps

Section 1 The Earth in Space

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

Rotation- the spinning of a planet on its axis.Revolution- The movement of one object around another. (the earth around the sun)

Section 2 Gravity and Motion4. 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)

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.

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.

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: When 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.

The MoonSection 4

18. Maria are dark flat areas on the surface of the moon. Latin for “seas.” Hardened rock from lava flows.

19. Craters are large round pits caused by impacts of meteoroids. Some are hundreds of kilometers across. They are all very old.

The Moon Continued

20. Highlands are lighter areas on the surface. Usually mountains.

Characteristics of the Moon

21. Characteristics of the moon: Dry, airless, small compared to the earth, and has large variations in surface temperature. 22. Size- 3,476 km acrossDensity- 1/8th as much as the Earth. Density is similar to the earths outer layers.Temperature- Range from 130 C to -180 CAtmosphere- No atmosphere. Not enough gravity.Water- No liquid water. May be ice near the poles

Formation of the Moon

23. Scientists believe that the moon was formed when the Earth and another planet sized object collided throwing out debris that eventually formed the moon.