Earth, Moon, and Sun - Earth in Space. Earth moves through space in two major ways: rotation & revolution.

Transcription

1 Earth, Moon, and Sun - Earth in Space How Earth Moves Earth moves through space in two major ways: rotation & revolution.

2 Earth, Moon, and Sun - Earth in Space Sunlight Striking Earth s Surface Near equator, sunlight strikes Earth s surface more directly & is less spread out than near poles.

3 Earth, Moon, and Sun - Earth in Space Seasons on Earth Earth has seasons because it is tilted as it revolves around the sun.

4 Earth, Moon, and Sun - Earth in Space Seasons on Earth The height of the sun above the horizon varies with the season.

5 Earth, Moon, and Sun - Earth in Space Seasons Activity Click the Active Art button to open a browser window and access Active Art about the seasons.

6 Earth, Moon, and Sun - Earth in Space Using Prior Knowledge Before you read, write what you know about seasons on Earth in a graphic organizer like the one below. As you read, write what you learn. What You Know 1. The sun s rays heat Earth. 2. Earth has seasons. 3. In the Northern Hemisphere, fall begins in September and spring begins in March. What You Learned 1. Areas where the sun hits Earth at a more direct angle are generally warmer than areas where the sun s rays are more spread out. 2. The tilt of Earth s axis as it moves around the sun causes seasons. 3. Around March 21 and September 22, day and night are each 12 hours long.

7 Earth, Moon, and Sun - Gravity and Motion Gravity The strength of the force of gravity between two objects depends on two factors: the masses of the objects and the distance between them.

8 Earth, Moon, and Sun - Gravity and Motion Gravity Versus Distance As a rocket leaves a planet s surface, the force of gravity between the rocket and the planet changes. Use the graph to answer the following questions.

9 Earth, Moon, and Sun - Gravity and Motion Gravity Versus Distance Reading Graphs: What two variables are being graphed? In what units is each variable measured? Force of gravity on the rocket in millions of newtons and distance from the planet s center in planetary radii

10 Earth, Moon, and Sun - Gravity and Motion Gravity Versus Distance Reading Graphs: What is the force of gravity on the rocket at the planet s surface? Four million newtons

11 Earth, Moon, and Sun - Gravity and Motion Gravity Versus Distance Reading Graphs: What is the force of gravity on the rocket at a distance of two units (twice the planet s radius from its center)? One million newtons

12 Earth, Moon, and Sun - Gravity and Motion Gravity Versus Distance Making Generalizations: In general, how does the force of gravity pulling on the rocket change as the distance between it and the planet increases? It decreases.

13 Earth, Moon, and Sun - Gravity and Motion Gravity and Inertia Newton concluded that two factors gravity and inertia combine to keep the moon in orbit around Earth.

14 Earth, Moon, and Sun - Gravity and Motion Asking Questions Before you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write answers to your questions. Question What is gravity? Answer Gravity is the force that attracts all objects toward one another. What is inertia? Inertia is the tendency of an object to resist a change in motion.

15 Earth, Moon, and Sun - Phases, Eclipses, and Tides Motions of the Moon The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.

16 Luna: The Moon of Earth, continued Phases of the Moon - The different appearances of moon due to changing relative position of Earth, sun and moon are called phases. Waxing and Waning - When moon is waxing, sunlit fraction we can see from Earth getting larger (light is right). When moon is waning, sunlit fraction getting smaller. 16

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18 Earth, Moon, and Sun - Phases, Eclipses, and Tides Phases of the Moon The phase of moon you see depends on how much of the sunlit side of the moon faces Earth.

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20 Earth, Moon, and Sun - Phases, Eclipses, and Tides The Moon s Orbit The moon s orbit is tilted about 5 degrees relative to Earth s orbit around the sun.

21 Earth, Moon, and Sun Vocabulary Terms Penumbra - (paene: almost & umbra: shadow) a space of partial illumination. Would see partial eclipse. Umbra - a shaded area. Would see total eclipse. Eclipse - the total or partial obscuring of one celestial body by another

22 Earth, Moon, and Sun - Phases, Eclipses, and Tides Solar Eclipse A solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from parts of Earth.

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24 Earth, Moon, and Sun - Phases, Eclipses, and Tides Lunar Eclipse During a lunar eclipse, Earth blocks sunlight from reaching the moon.

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27 Luna: The Moon of Earth, continued Eclipses - When the shadow of one celestial body falls on another, an eclipse occurs. Solar Eclipses - During a total solar eclipse, the disk of the moon completely covers the disk of the sun, as shown below. 27

28 Luna: The Moon of Earth, continued Lunar Eclipses - During lunar eclipse, moon passes through Earth s shadow. The Tilted Orbit of the Moon - You don t see a solar & lunar eclipse every month because moon s orbit around Earth is tilted. 28

29 Earth, Moon, and Sun - Phases, Eclipses, and Tides Tides Tides occur mainly due to the difference in the force of gravity between the moon and different parts of Earth.

30 Earth, Moon, and Sun - Phases, Eclipses, and Tides Spring and Neap Tides When Earth, the sun, and the moon are in a straight line, a spring tide occurs. When the moon is at a right angle to the sun, a neap tide occurs.

31 Earth, Moon, and Sun - Phases, Eclipses, and Tides Previewing Visuals Preview Figure 11. Then write two questions you have about the diagram of the phases of the moon in a graphic organizer like the one below. As you read, answer your questions. Earth s History Q. Why does the moon have phases? A. The changing relative positions of the moon, Earth, and the sun cause the phases of the moon. Q. Do we see different sides of the moon as the phases of the moon appear? A. No; the same side of the moon always faces Earth.

32 Earth, Moon, and Sun - Earth s Moon The Moon s Surface Features on the moon s surface include maria, craters, and highlands.

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35 Earth, Moon, and Sun - Earth s Moon The Moon s Size Moon is 3,476 km in diameter, a little less than distance across contiguous Untied States.

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37 Moon s Surface Maria - dark, flat areas, which Galileo named (Mah ree uh); he thought incorrectly that they were oceans. Actually hardened rock from huge lava flows - 3 to 4 Gya. Craters - First accurately described by Galileo - round pits ranging in size from marble to 2,240 km in diameter (from Phoenix to Chicago), made - meteoroid impacts. Highlands - Galileo inferred light-colored features highlands. By shadows. 37

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40 Luna: The Moon of Earth The Surface of the Moon - surfaces of bodies that have no atmospheres, such as moon, preserve a record of almost all of the impacts that bodies have had. Moonquakes have shown core of moon may be molten. 40

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42 Earth, Moon, and Sun - Earth s Moon The Origin of the Moon Scientists theorize that a planet-sized object collided with earth to form the moon.

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44 Earth, Moon, and Sun - Earth s Moon Identifying Main Ideas As you read the section The Moon s Surface, write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea. Main Idea The moon s surface has a variety of features such as Detail Detail Detail Dark, flat areas called maria, which formed from huge lava flows Large, round pits called craters, which were caused by the impact of meteoroids Highlands, or mountains, which cover much of the moon s surface

45 Earth, Moon, and Sun Graphic Organizer Earth On its axis rotates revolves Around the sun causing causing Night and day Years

46 The Beginnings of Rocket Science About 100 years ago, Russian high school teacher Konstantin Tsiolkovsky proposed that machines called rockets could take people to outer space. Rocket - machine that uses escaping gas from burning fuel to move. 46

47 The Beginnings of Rocket Science A Boost for Modern Rocketry - While Tsiolkovsky proved scientifically that rockets could reach outer space, he never built any rockets himself. American physicist & inventor Robert Goddard launched the first successful liquid-fuel rocket in

48 The Beginnings of Rocket Science Goddard tested more than 150 rocket engines, by the time of WW II, Goddard s work began to interest US military. Goddard s work drew much attention because of terrifying new weapon that the German army had developed. 48

49 From Rocket Bombs to Rocket Ships Toward end of WW II, Nazi Germany developed new weapon known as V-2 rocket V-2 rocket could deliver explosives from German military bases to London a distance of ~350 km. V-2 rocket developed by team led by Wernher von Braun, young Ph.D. student whose research was supported by German military. 49

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53 Rocket Bombs to Rocket Ships, continued near end of war, von Braun & entire research team surrendered to advancing America army. United States thus gained 127 of best German rocket scientists. With this gain, rocket research in the United States boomed in the 1950s. 53

54 Rocket Bombs to Rocket Ships, continued Birth of NASA - End of World War II marked beginning of Cold War, a long period of political tension between US & Soviet Union. Cold War was marked by an arms race & by competition in space technology. 54

55 Rocket Bombs to Rocket Ships, continued In response to Soviet advances in space, U.S. government formed National Aeronautics and Space Administration, or NASA, in NASA combined all of rocketdevelopment teams in US (Brain Trust). Their cooperation led to development of many rockets, including those shown on next slide. 55

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57 How Rockets Work For Every Action... Newton s third law of motion states that for every action there is an equal & opposite reaction. Can be demonstrated if you blow up a balloon & let it go. Air rushing backward from balloon (the action) results in forward motion of balloon (the reaction). Rockets work in same way. In fact, rockets were once called reaction devices. 57

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59 How Rockets Work, continued Because exhaust gases are under extreme pressure, they exert a huge amount of force. The force that accelerates a rocket is called thrust. Thrust - pushing or pulling force exerted by engine of aircraft or rocket. 59

60 How Rockets Work, continued Because exhaust gases are under extreme pressure, they exert a huge amount of force. The force that accelerates a rocket is called thrust. Thrust - pushing or pulling force exerted by engine of aircraft or rocket. 60

61 How Rockets Work, continued You Need More Than Rocket Fuel - Rockets burn fuel to provide thrust that propels them. In order for something to burn, oxygen must be present. Although oxygen is plentiful at Earth s surface, there is little or no oxygen in upper atmosphere & in outer space. 61

62 How Rockets Work, continued For this reason, rockets that go into outer space must carry enough oxygen with them to be able to burn their fuel. The space shuttles, for example, carry hundreds of thousands of gallons of liquid oxygen. This oxygen is needed to burn the shuttle s rocket fuel. 62

63 How Rockets Work, continued The gravitational pull of Earth is main factor a rocket must overcome. A rocket must reach a certain velocity, or speed and direction, to orbit or escape the Earth. 63

64 How Rockets Work, continued Orbital Velocity and Escape Velocity - For a rocket to orbit the Earth, it must have enough thrust to reach orbital velocity. Orbital velocity - speed & direction a rocket must travel in order to orbit a planet or moon. The lowest possible speed a rocket may go and still orbit Earth is about 8 km/s (17,927 mi/h). If rocket goes any slower, it will fall back to Earth. 64

65 The First Satellites An artificial satellite - any humanmade object placed in orbit around a body in space. There are many kinds of artificial satellites, including weather satellites, communications satellites, and remotesensing satellites. 65

66 The First Satellites, continued In 1957, Soviets launched first artificial satellite, Sputnik 1. It orbited for 57 days before it fell back to Earth and burned up in the atmosphere. Two months later, Sputnik 2 carried the first living being into space a dog named Laika. 66

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71 Choosing Your Orbit Satellites are placed in different types of orbits. All of the early satellites were placed in low Earth orbit. Low Earth orbit (LEO) is an orbit less than 1,500 km above the Earth s surface. A satellite in LEO moves around the Earth very quickly and can provide clear images of the Earth. However, this motion can place a satellite out of contact much of the time. 71

72 Choosing Your Orbit, continued Most communications and weather satellites circle the Earth in geostationary orbit. Geostationary orbit (GEO) is an orbit that is about 36,000 km above the Earth s surface and in which a satellite is above a fixed spot on the equator. A satellite in GEO is always above the same spot on Earth. Ground stations are in continuous contact with these satellites so that communications will not be interrupted. 72

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