Astronomy Chapter 1 Earth, Moon and Sun

1. Astronomy Chapter 1Earth, Moon and Sun Earth in Space Section 1

2. Vocabulary • Astronomy: the study of the moon, stars and other objects in space • Axis: The imaginary line that passes through Earth’s center and the North and South poles • Rotation: Earth’s spinning on its axis • Revolution: The movement of one object around another object • Orbit: Earth’s path around the sun • Latitude: the measurement of distance from the equator expressed in degrees north or south

3. Vocabulary • Solstice: The day when the noon sun is directly overhead. (there is a winter and a summer solstice) • Equinox: when nighttime and daytime are about the same • Vernal equinox: the spring equinox that occurs around March 21 and marks the beginning of spring in the Northern Hemisphere • Autumnal equinox: the fall equinox that occurs around September 23 and marks the beginning of fall in the Northern Hemisphere

4. Main Ideas • Earth’s rotation on its axis causes day and night • Earth has seasons because its axis is tilted as it moves around the sun • Earth’s axis is tilted at an angle of 23.5 degrees • It is warm near the equator because sunlight hits Earth’s surface directly and is less spread out

5. Guiding Questions • Why do the sun and moon seem to move each day? • Explain the process that causes day and night • What two factors cause the cycle of the seasons? • Compare rotation and revolution • What do the words solstice and equinox mean? How are they related to the position of Earth’s axis?

6. Phases, Eclipses, and TidesSection 2

7. Vocabulary • Phases: The different shapes of the moon you see from Earth • Eclipse: occurs when an object in space comes between the sun and a third object, and cases a shadow on that object. • Solar eclipse: occurs when the moon passes between Earth and the sun, blocking the sunlight from reaching Earth • Lunar eclipse: occurs at a full moon when Earth is directly between the moon and the sun. • Umbra: the darkest part of the moon’s shadow • Penumbra: the larger part of the shadow of the sun that is visible from Earth

8. Vocabulary • Tides: the rise and fall of water very 12.5 hours or so • Gravity: a natural force that pulls the moon and earth toward each other. • Spring tide: the combined forces produce a tide with the greatest difference between low and high tide • Neap tide: a tide that is produced with the least difference between low and high tide

9. Main Ideas • The positions of the moon, Earth, and the sun cause the phases of the moon, eclipses, and tides • The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth • When the moon’s shadow hits Earth or Earth’s shadow hits the moon, an eclipse occurs • Tides occur mainly because of differences in how much the moon pulls on different parts of Earth

10. Guiding Questions • How many days does it take the moon to revolve once around Earth? • Since the moon does not produce light, how can you see it? • Why are a day and a year on the moon the same length? • Why are there two high tides and two low tides each day?

11. Rockets and SatellitesSection 3

12. Vocabulary • Satellite: any natural or artificial object that revolves around an object in space, just as the moon revolves around Earth • Geosynchronous orbits: orbits that revolve around Earth at the same rate that Earth rotates

13. Main Ideas • A rocket moves forward when gases expelled from the rear of the rocket push it in the opposite direction • Satellites and space stations are used for communications, navigation, collecting weather data, and research • Multistage rockets have three states or sections. Each of the first two stages burns all its fuel and then drops off. The next stage then takes over. Only part of the third stage reaches the rocket’s destination.

14. Guiding Questions • How does a rocket work? • Describe three uses of satellites and space stations • Which stage of multistage rocket reaches the final destination?

15. Earth’s MoonSection 4

16. Vocabulary • Telescope: a device built to study distant objects by making them appear closer • Crater: a round pit on the moon’s surface • Maria: Dark, flat regions on the moon’s surface

17. Main Ideas • Features, on the moon’s surface include craters, highlands, and maria • Much of what scientists have learned about the moon came from detailed study of the moon rocks

18. Guiding Questions • Name three kinds of features that Galileo saw on the moon’s surface • What did the Apollo astronauts do on the moon? • How did the craters form on the moon?