1. Chapter 15 Formation of the Solar System Section 1 A Solar System Is BornA Solar System Is Born Section 2 The Sun: Our Very Own StarThe Sun: Our Very Own Star Section 3 The Earth Takes ShapeThe Earth Takes Shape Section 4 Planetary MotionPlanetary Motion Preview Concept Mapping

2. Chapter 15 Question of the Day Could astronauts land on a star in the same way that they landed on the moon? Explain why or why not. For the 4 th 9 Weeks I want you to keep every QOD on the same piece of paper(s). If you miss one due to an absence then for that day write “Absent”. This will be taken up at the end of the 9 Weeks for a TEST grade. Section 1 A Solar System Is Born

3. Chapter 15 Explain the relationship between gravity and pressure in a nebula. Describe how the solar system formed. Objectives Section 1 A Solar System Is Born

4. Chapter 15 The Solar Nebula The ingredients for building solar systems are found in outterspace in areas called nebulas. A nebula is a large cloud of gas and dust in interstellar space. Section 1 A Solar System Is Born

5. Chapter 15 The Solar Nebula, continued Nebulas contain gases (mainly H and He) and dust (mainly C and Fe). The gases and dust interact with gravity and pressure to form stars and planets. They next few slides show how gravity and pressure interact. Section 1 A Solar System Is Born

6. Chapter 15 The Solar Nebula, continued Gravity Pulls Matter Together Gravity holds the matter in a nebula together. Gravity causes the particles in a nebula to be attracted to each other. Section 1 A Solar System Is Born

7. Chapter 15 The Solar Nebula, continued Pressure Pushes Matter Apart Outward pressure keeps nebulas from collapsing. Temperature is a measure of kinetic energy, or energy of motion, of the particles in an object and affects the pressure. If the particles have little kinetic energy, they move slowly and the temperature is very low. If the particles move fast, the temperature is high. Section 1 A Solar System Is Born

8. Chapter 15 The Solar Nebula, continued As the particles in a nebula move around they crash into each other and increase pressure. When the particles move closer together, collisions cause the pressure to increase and particles are pushed apart. Section 1 A Solar System Is Born

9. Chapter 15 The Solar Nebula, continued Outward pressure balances the inward gravitation pull and keeps the cloud from collapsing. With pressure and gravity balanced, the nebula become stable. Section 1 A Solar System Is Born

10. Chapter 15 Upsetting the Balance The balance between gravity and pressure can be upset if two nebulas collide or if a nearby star explodes. These events compress, or push together, small regions of a nebula together and increase the temperature. Section 1 A Solar System Is Born

11. Chapter 15 Upsetting the Balance, continued As the temperature increases, new stars and planets may form. The solar nebula is the cloud of gas and dust that collasped and formed our solar system. Section 1 A Solar System Is Born

12. Chapter 15 How the Solar System Formed After the solar nebula began to collapse, it took about 10 million years for the solar system to form. As the nebula collapsed, it became denser and the attraction between the gas and dust particles increased. The center of the cloud became very dense and hot. Section 1 A Solar System Is Born

13. Chapter 15 How the Solar System Formed, continued Much of the gas and dust in the nebula began to rotate slowly around the center of the cloud. Over time, the rotating solar nebula flattened into a rotating disk. All of the planets still follow this rotation today. Section 1 A Solar System Is Born

14. Chapter 15 How the Solar System Formed, continued From Planetesimals to Planets Bits of dust circled the center of the solar nebula and stuck together to form golf ball-sized bodies. Planetesimals, or “small planets”, are a lot of bits of dust sticking together to make larger pieces. Some of these planetesimals are part of the cores of current planets. Section 1 A Solar System Is Born

15. Chapter 15 How the Solar System Formed, continued Gas Giant or Rocky Planet? The largest planetesimals formed near the outside of the rotating solar disk, where the gasses were located. These outer planets in the rotation grew large and became the gas giants: Jupiter, Saturn, Uranus, and Neptune. Section 1 A Solar System Is Born

16. Chapter 15 How the Solar System Formed, continued Closer to the center of the nebula temperatures were too hot for gases to remain. The inner planets in our solar system (Mercury, Venus, Earth, and Mars) are made of mostly rocky material because the gas did not remain. Section 1 A Solar System Is Born

17. Chapter 15 How the Solar System Formed, continued The Birth of a Star As the planets were forming, other matter in the solar nebula was traveling toward the center. The center became so dense and hot that hydrogen atoms began to fuse, or join, to form helium. Fusion released huge amounts of energy and created enough outward pressure to balance the inward pull of gravity. When everything was balanced, our sun was born. Section 1 A Solar System Is Born

18. Chapter 15 How the Solar System Formed, continued The structure of a nebula and the process that led to the birth of the solar system are reviewed in the following Visual Concepts presentation. Section 1 A Solar System Is Born Visual Concept

19. Chapter 15 Section 2 The Sun: Our Very Own Star Question of the Day Henry David Thoreau once said, “The sun is but a morning star.” Explain what you think this quotation means.

20. Chapter 15 Describe the basic structure and composition of the sun. Explain how the sun generates energy. Describe the surface activity of the sun, and identify how this activity affects Earth. Objectives Section 2 The Sun: Our Very Own Star

21. Chapter 15 The Structure of the Sun The sun is a large ball of gas made mostly of hydrogen and helium held together by gravity. Although the sun may appear to have a solid surface, it does not. The visible surface of the sun starts at the point where the gas becomes so thick that you cannot see through it. The sun is made of several layers. Section 2 The Sun: Our Very Own Star

22. Chapter 15 Section 2 The Sun: Our Very Own Star

23. Chapter 15 Energy Production in the Sun The sun has been shining on the Earth for about 4.6 billion years. Burning fuel for energy?.....NO! The amount of energy that is released by burning would not be enough to power the sun. If the sun were simply burning, it would last for only 10,000 years. Section 2 The Sun: Our Very Own Star

24. Chapter 15 Energy Production in the Sun, continued Burning of Shrinking? Releasing energy because of gravitational shrinking?......NO! While the release of gravitational energy is more powerful than burning, it is not enough to power the sun. If all of the sun’s gravitational energy were released, the sun would last only 45 million years. Section 2 The Sun: Our Very Own Star

25. Chapter 15 Energy Production in the Sun, continued Nuclear Fusion Scientist now know that the sun gets its energy from nuclear fusion. Matter can change into energy according to his famous formula: E  mc 2 (E is energy, m is mass, and c is the speed of light.) Because c is such a large number, tiny amounts of matter can produce a huge amount of energy. Section 2 The Sun: Our Very Own Star

26. Chapter 15 Energy Production in the Sun, continued The process by which two or more low-mass nuclei join together, or fuse, to form another nucleus is called nuclear fusion. In this way, four hydrogen nuclei can fuse to form a single nucleus of helium. During the process, energy is produced. Section 2 The Sun: Our Very Own Star

27. Chapter 15 Energy Production in the Sun, continued In the center of the sun temperature and pressure are very high. Hydrogen nuclei have enough energy to overcome the repulsive force, and hydrogen fuses into helium, as shown on the next slide. Section 2 The Sun: Our Very Own Star

28. Chapter 15 Section 2 The Sun: Our Very Own Star

29. Chapter 15 Energy Production in the Sun, continued Energy produced in the center, or core, of the sun takes millions of years to reach the sun’s surface. Energy passes from the core through a very dense region called the radiative zone. The matter in the radiative zone is so crowded that light and energy are blocked and sent in different directions. Section 2 The Sun: Our Very Own Star

30. Chapter 15 Section 2 The Sun: Our Very Own Star Energy Production in the Sun, continued Eventually, energy reaches the convective zone. Gases circulate in the convective zone, which is about 200,000 km thick. Hot gases in the convective zone carry the energy up to the photosphere, the visible surface of the sun. From the photosphere, energy leaves the sun as light, which takes only 8.3 minutes to reach Earth.

31. Chapter 15 Solar Activity The churning of hot gases in the sun, combined with the sun’s rotation, creates magnetic fields that reach far out into space. The flow of magnetic fields from the sun is called the solar wind. Sometimes, solar wind interferes with the Earth’s magnetic field. This type of solar storm can disrupt TV signals and damage satellites. Section 2 The Sun: Our Very Own Star

32. Chapter 15 Solar Activity, continued Sunspots The sun’s magnetic fields tend to slow down activity in the convective zone. When activity slows down, areas of the photosphere become cooler than the surrounding area. Sunspots are cooler, dark spots of the photosphere of the sun. Some sunspots can be as large as 50,000 miles in diameter. Section 2 The Sun: Our Very Own Star

33. Chapter 15 Sunspots Click below to watch the Visual Concept. Visual Concept Section 2 The Sun: Our Very Own Star

34. Chapter 15 Solar Activity, continued Climate Confusion Solar activity can affect climate on Earth. Sunspot activity can affect the Earth. Some scientists have linked the period of low sunspot activity, 1645- 1715, with a period of very low temperatures that Europe experienced during that time, known as he “Little Ice Age.” Section 2 The Sun: Our Very Own Star

35. Chapter 15 Solar Activity, continued Solar Flares The magnetic fields responsible for sunspots also cause solar flares. Solar flares are regions of extremely high temperatures and brightness that develop on the sun’s surface. When a solar flare erupts, it sends huge streams of electrically charged particles into the solar system. Solar flares can interrupt radio communications on the Earth and in orbit. Section 2 The Sun: Our Very Own Star

36. Chapter 15 Question of the Day The Earth is approximately 4.6 billion years old. The first fossil evidence of life on Earth has been dated between 3.7 billion and 3.4 billion year ago. Write a few sentences for your QOD describing what Earth might have been like during the first billion years of its existence. Section 3 The Earth Takes Shape

37. Chapter 15 Describe the formation of the solid Earth. Describe the structure of the Earth. Explain the development of Earth’s atmosphere Objectives Section 3 The Earth Takes Shape

38. Chapter 15 The Earth is mostly made of rock. Nearly three-fourths of its surface is covered with water. Our planet is surrounded by a protective atmosphere of mostly nitrogen and oxygen, and smaller amounts of other gases. Formation of the Solid Earth Section 3 The Earth Takes Shape

39. Chapter 15 The Earth formed as planetesimals in the solar system collided and combined. From what scientists can tell, the Earth formed within the first 10 million years of the collapse of the solar nebula. Section 3 The Earth Takes Shape

40. Chapter 15 The Effects of Gravity When the Earth was still small, it was not round and had little gravity. As the Earth got bigger, gravity increased. When the Earth got about 300 mi around, the force of gravity becomes greater than the strength of the rock. As the Earth grew to final size, the rock at its center was crushed by gravity and the planet started to become round. Section 3 The Earth Takes Shape

41. Chapter 15 The Effects of Heat As the Earth was changing shape, it was also heating up thus causing it to rotate more. As planetesimals continued to collide with the Earth, they heated the planet. Radioactive material inside the Earth also heated the young planet. Section 3 The Earth Takes Shape

42. Chapter 15 After Earth reached a certain size, the temperature rose faster than the interior could cool, and the rocky material inside began to melt into magma. Today, the Earth is still cooling from the energy that was generated when it formed. Volcanoes, earthquakes, and hot springs are effects of this energy trapped inside the Earth. Section 3 The Earth Takes Shape

43. Chapter 15 Denser materials, such as nickel and iron, sank to the center of the Earth and formed the core. Lighter materials floated to the surface and became the crust. This process is shown on the next slide. How the Earth’s Layers Formed Section 3 The Earth Takes Shape

44. Chapter 15

45. The crust is the thin and solid outermost layer of the Earth above the mantle. It is 5 to 100 km thick. Crustal rock is made of materials that have low densities, such as oxygen, silicon, and aluminum. How the Earth’s Layers Formed, continued Section 3 The Earth Takes Shape

46. Chapter 15 The mantle is the layer of rock between the Earth’s crust and core. It extends 2,900 km below the surface. Mantel rock is made of materials such as magnesium and iron. It is denser than crustal rock. How the Earth’s Layers Formed, continued Section 3 The Earth Takes Shape

47. Chapter 15 The core is the central part of the Earth below the mantle, almost 6,400 km below the surface. It contains the densest materials, including nickel and iron. How the Earth’s Layers Formed, continued Section 3 The Earth Takes Shape

48. Chapter 15 Earth’s Early Atmosphere Scientists think that the Earth’s early atmosphere was a mixture of gases that were released as the Earth cooled. During the final stages of the Earth’s formation, its surface was very hot—even molten in places. The molten rock released large amounts of carbon dioxide and water vapor. Formation of the Earth’s Atmosphere Section 3 The Earth Takes Shape

49. Chapter 15 Earth’s Changing Atmosphere As the Earth cooled and its layers formed, the atmosphere changed again. This atmosphere probably formed from volcanic gases. Volcanoes released chlorine, nitrogen, and sulfur, in addition to large amounts of carbon dioxide and water vapor. Some of this water vapor may have condensed to form the Earth’s first oceans. Formation of Earth’s Atmosphere, continued Section 3 The Earth Takes Shape

50. Chapter 15 Comets, which are planetesimals made of ice, may have contributed to this change of Earth’s atmosphere. As they crashed into the Earth, comets brought in a range of elements, such as carbon, hydrogen, oxygen, and nitrogen. Comets also may have brought some of the water that helped form the oceans. Formation of Earth’s Atmosphere, continued Section 3 The Earth Takes Shape

51. Chapter 15 The Source of Oxygen Sometime before 3.4 billion years ago, organisms that produced food by photo-synthesis appeared. Photosynthesis is the process of absorbing energy from the sun and carbon dioxide from the atmosphere to make food. During the process of making food, these organisms released oxygen—a gas that was not abundant in the atmosphere at the time. The Role of Life Section 3 The Earth Takes Shape

52. Chapter 15 Section 4 Planetary Motion Question of the Day A mnemonic device is a phrase, rhyme, or anything that helps you remember a fact. Create a mnemonic device that will help you differentiate between planetary rotation and revolution. Rotation – the spinning of an object, such as a planet, on it’s axis. Revolution – is one complete trip along an orbit.

53. Chapter 15 Explain the difference between rotation and revolution. Describe three laws of planetary motion. Describe how distance and mass affect gravitational attraction. Objectives Section 4 Planetary Motion

54. Chapter 15 Each planet spins on its axis. The spinning of a body, such a planet, on its axis is called rotation (on Earth it is 24 hours). The orbit is the path that a body follows as it travels around another body in space. A revolution is one complete trip along an orbit (on Earth it is 1 year). A Revolution in Astronomy Section 4 Planetary Motion

55. Chapter 15 Earth’s Rotation and Revolution Section 4 Planetary Motion

56. Chapter 15 Johannes Kepler made careful observations of the planets that led to important discoveries about planetary motion. Kepler’s First Law of Motion - planets move around the sun in elliptical orbits. A Revolution in Astronomy, continued Section 4 Planetary Motion

57. Chapter 15 Ellipse Section 4 Planetary Motion

58. Chapter 15 Kepler’s Second Law of Motion - planets seemed to move faster when they are close to the sun and slower when they are farther away. A Revolution in Astronomy, continued Section 4 Planetary Motion

59. Chapter 15 Kepler’s Third Law of Motion - planets more distant from the sun, such as Saturn, take longer to orbit the sun. A Revolution in Astronomy, continued Section 4 Planetary Motion

60. Chapter 15 Kepler did not understand what causes the planets farther from the sun to move slower than the closer planets. Sir Isaac Newton’s description of gravity provides an answer. Newton to the Rescue! Section 4 Planetary Motion

61. Chapter 15 Newton’s Law of Universal Gravitation states that the force of gravity depends on the product of the masses of the objects divided by the square of the distance between the objects. g = (m 1 X m 2 ) / (d 1 -d 2 ) 2 If two objects are moved farther apart, there will be less gravitational attraction between them. Newton to the Rescue! continued Section 4 Planetary Motion

62. Chapter 15 Orbits Falling Down and Around Inertia is an object’s resistance to change in speed or direction until an outside force acts on the object. Gravitational attraction keeps the planets in their orbits. Inertia keeps the planets moving along their orbits. Newton to the Rescue! continued Section 4 Planetary Motion

63. Chapter 15 Gravity and the Motion of the Moon Section 4 Planetary Motion