Chapter 1: Earth , Moon, and Sun

1. Chapter 1: Earth, Moon, and Sun By Mrs. Shaw

2. Chapter 1: Earth, Moon, Sun • LearningGoals: • Studentswillbeableto • explainthedifferencebetweenrevolution and rotation and howtheseterms are relatedto time onEarth. • explainwhytheEarthisheatedunevenly and howthat relates totheweatheronEarth • explainhowthetilt of theEarth causes seasonsonEarth. • explainwhat causes thephases of the Moon, tides, and eclipses and describe them. • ExplaintheLaw of Universal Gravitation and howit relates tothemotion of objects in space.

3. Lesson 1: Earth in Motion What causes the Earth to be heated unevenly? • Light and heat from the sun is more spread out at the poles and more direct at the equator due to the Earth’s spherical shape. The Sun produces light and thermal energy through a process called nuclear fusion.

4. Differentiate between the terms – rotation and revolution and explain their relation to the Earth’s motion. • Earth rotates counterclockwise (spins) on it’s axis fully every 24 hours. The effect of this is the day/ night cycle. • A revolution is when one object moves around another. Earth revolves around the sun every 365.24 days or 1 year. • An orbit is the path an object takes as it revolves around another.

5. What causes seasons? • Seasons are caused by the tilt of the Earth on it’s axis (23.45 degrees) • When the northern hemisphere is experiencing summer the southern hemisphere is experiencing winter.

6. What is the difference between the terms solstice and equinox? Solstices happen when the tilt of the Earth is either towards or away from the Sun. Equinoxes happen when the tilt of the Earth is NOT towards or away from the sun . . . . .so both hemispheres get equal sunlight.

7. Summer Solstice in the Northern hemisphere happens when the tilt of the Earth is toward the Sun. Winter Solstice in the Northern hemisphere happens when the tilt of the Earth is away from the Sun.

8. Lesson 2: Earth’s Moon How do we see the moon? What is the Moon? • We are only able to see the Moon because the sunlight is reflected off of it. • Our Moon is a satellite of Earth, made of a large hard rock with no atmosphere, no water, and no plate tectonics.

9. Earth, Moon, Sun Comparisons • Distance from the Earth to the Sun - 149,597,890 km • Distance from Earth to the Moon - 384,467 km • Diameter • Sun - 1,391,940 km • Earth - 12,742 km • Moon - 3,476 km • The diameter of the Sun is about 100 times bigger than the Earth and 400 times bigger than the Moon. • If the Sun was as big as a soccer ball, the Earth would be about the size of a small dried pea. The distance between them would be 2.3 m. • You could fit 107 Suns between the Sun and the Earth , http://sciencenetlinks.com/interactives/messenger/psc/PlanetSize.html

10. How does the Moon revolve around the Earth? • Gravity and inertia both act on the Moon to cause it to revolve around the Earth. Review: Inertia is the ability of an object to resist a change in motion.

11. The Moon’s rotation and revolution How long does it take for the Moon to revolve around the Earth? How often does the Moon make one full rotation? • The moon revolves around the Earth every 27.3 days. • The moon rotates on its axis every 27.3 days.

12. If the rotation and revolution of the moon take 27.3 days why is the lunar phase cycle 29.5 days? • As the Moon completes one orbit around the Earth, the Earth has moved in its orbit around the Sun by approximately 26°. Because of the Earth’s movement, the Moon is not in exactly the same spot relative to the Sun when it completes its lunar orbit. It takes approximately 2 more days for the Moon to travel back to the same position relative to the Sun. This is why the lunar phase cycle, Synodic Month, takes approximately 29.5 days to complete even though the lunar orbit, Sidereal Month, was completed in approximately 27.3 days.

13. How do we only see one side of the moon? • Because the Moon rotates at the same rate it revolves, we always see the same side of the Moon.

14. Why do we see different shapes of the moon? The revolution of the Moon around the Earth makes the Moon appear as if it is changing shape in the sky. This is caused by the different viewing angles from which we see the bright part of the Moon’s surface. Waxing phases are when the moon appears to be getting larger. Waning phases are when the moon appears to be getting smaller

16. Lesson 3: Eclipses and Tides Differentiate between a solar and a lunar eclipse. • Lunar eclipse: when the moon passes through Earth’s shadow and it is either not visible or appears orange. • Solar eclipse: when the moon passes between the Earth and the Sun and causes the sun to be blocked.

17. Why do we not have a solar and lunar eclipse somewhere on Earth every month? Because the moons orbit is tilted about 5 degrees it usually passes just above or below the Earth’s shadow so we only see a lunar eclipse about every 6 months. Solar eclipses can only be seen when the umbra of the Moon’s shadow sweeps across Earth’s surface. The track (Path of Totality) is usually 10,000 miles long but only 100 miles wide. It can only be seen for a few minutes before it moves.

18. What causes tides and how are they related to the phases of the moon? Tides are caused by the gravitational pull of the Moon on the Earth’s oceans. Tides are highest when the moon, earth, and sun line up and the net force is increased.

19. Review of Universal Law of Gravitation • Law states that “every object with mass has a gravitational pull on every other object with mass”. • The amount of gravitational pull depends on two things: mass and distance.

20. What are Spring and Neap Tides? • Spring Tides happen when the moon, earth, and sun line up. (full and new moon) • Neap Tides happen when the moon is at a right angle to the sun (1st and 3rd quarter moon).