1. Our Solar System in the Universe Chapters 25 & 26

3. CH 25: Our Solar System WHAT YOU ARE GOING TO LEARN ABOUT: Exploring the Solar System – history The Earth-Moon System The Inner Solar System The Outer Solar System The Origin of the Solar System

4. How do science concepts apply to your world? Here are some questions you’ll be able to answer after you read this chapter. ■ How does a spacesuit work? ■ Why shouldn’t you park a car too close to the ocean’s edge? ■ Why isn’t Earth covered by craters? ■ Did Mars once have liquid water? ■ Where, besides Earth, is life most likely to occur in our solar system? ■ What lies at the outer edges of the solar system? ■ Why do comets have tails? ■ Are there planets around other stars?

5. FIND the ANSWERS - ACTIVITY How do science concepts apply to your world? 1. ■ How does a spacesuit work? (Section 25.1) 2. ■ Why shouldn’t you park a car too close to the ocean’s edge? (Section 25.2) 3. ■ Why isn’t Earth covered by craters? (Section 25.3) 4. ■ Did Mars once have liquid water? (Section 25.3) 5. ■ Where, besides Earth, is life most likely to occur in our solar system? (Section 25.4) 6. ■ What lies at the outer edges of the solar system? (Section 25.4) 7. ■ Why do comets have tails? (page 816) 8. ■ Are there planets around other stars? (Section 25.5)

6. CH 25: Pre-Quiz 1. What determines the strength of the gravitational attraction between two objects? a. Mass and weight b. Weight and distance c. Mass and distance d. Distance and density 2. What are the two most abundant gases in Earth’s atmosphere? 3. True or False: Earth’s atmosphere plays a role in regulating its surface temperature. 4. What is Newton’s first law of motion? 5. Describe Earth’s structure. What are the three main layers? 6. Explain the process of condensation.

7. Ch 25: Pre-Quiz - KEY 1. What determines the strength of the gravitational attraction between two objects? (c) a. Mass and weight b.Weight and distance c. Mass and distance d. Distance and density 2. What are the two most abundant gases in Earth’s atmosphere? (Nitrogen and oxygen) 3. True or False: Earth’s atmosphere plays a role in regulating its surface temperature. (True. Earth’s atmosphere plays a major role in keeping surface temperatures in their present ranges.) 4. What is Newton’s first law of motion? (The state of motion of an object does not change as long as there is no net force acting on it.) 5. Describe Earth’s structure. What are the three main layers? (The three main layers are the crust, or rocky outer layer; the mantle, a thick layer of hot, solid rock; and the core, a large sphere found in Earth’s center, mostly made of iron and nickel.) 6. Explain the process of condensation. (In condensation, a gas changes into a liquid as it cools.)

8. Why do we care to study this?

9. The Hubble Space Telescope Has Orbited Earth For 25 Years 1 light year = 5.87849981 x 10 12 miles

10. What have you observed? …the first step in scientific methods

11. What have you observed? Ancient Civilizations did too… – most objects in the sky seem to be in a state of slow but steady motion. The sun and moon appear to rise in the east and set in the west. The stars move across the sky in a fixed pattern. – a few bright star-like objects seemed to wander slowly among the fixed patterns of stars. called planets, from the Greek word for “wanderers.” – Saw five planets that can be seen with the unaided eye: Mercury, Venus, Mars, Jupiter, and Saturn.

12. Models of the Solar System Geocentric Model Most ancient Greeks thought that all the stars and planets lay on the inside of a giant sphere that revolved around Earth once a day. Such a model is called a geocentric model. Which is it? Ptolemy’s geocentric model was widely accepted for nearly 1400 years

13. Models of the Solar System Heliocentric Model The Greek astronomer Aristarchus developed a heliocentric model, with the sun at the center. His model was not accepted by most ancient Greeks. The geocentric model could explain all observations made at that time. 1500s - Copernicus realized that the motion of the planets could be more simply explained if they are revolving around the sun rather than around Earth. The observations of Italian scientist Galileo and other scientists later proved that the heliocentric model was correct.

14. Figure 2 Andreas Cellarius drew these maps of the geocentric model (left) and heliocentric model (right) in the 1660s. Where does Earth appear in each diagram?

15. Check your UNDERSTANDING!

17. How are the geocentric and heliocentric models of the solar system different? Models of the Solar System In a geocentric model, Earth is stationary while objects in the sky move around it. In a heliocentric model, Earth and the other planets revolve around the sun.

18. What do you see? As Earth rotates, it seems that we are stationary and all of the objects in the sky are spinning around us. The northern stars appear to circle around the North Star because Earth’s axis points toward a spot in the sky close to that star.North Star The apparent motions of the sun, moon, and stars result from Earth’s daily rotation on its axis.

19. Planetary Orbits What keeps the planets in orbit around the sun? Gravity and inertia combine to keep the planets in orbit around the sun. INERTIA Newton’s first law of motion states that an object in motion continues to move in a straight line at a constant speed unless acted upon by a force.  This property of matter is known as inertia. GRAVITY Newton realized that the sun must be exerting a gravitational force on the planets that keeps them in orbit.

20. Johannes Kepler *discovered that the orbit of a planet around the sun is not a circle, but an ellipse. An ellipse looks like an oval, or a circle that has been stretched out along one axis. Most planets’ orbits are nearly circular, and so are only slightly elliptical. The plane of Earth’s orbit is called the ecliptic plane.

21. What bodies make up the solar system? Name them…

22. The ancients knew of six planets. Three more planets were discovered with the aid of telescopes: Uranus in 1781 Neptune in 1846 Pluto in 1930 (Pluto was later reclassified as a dwarf planet.)

23. 9 Planets Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Remember the mnemonic device for this is: mnemonic device My very educated mother just served us Nachos plain.

24. Components of the Solar System Our solar system consists of: – Sun – Planets Planets their moons – Variety of smaller objects that mostly revolve in the same plane around the sun.

25. What is a Moon? Except for Mercury and Venus, all of the planets have moons. A moon is a relatively small natural body in space that revolves around a planet.moon

26. Jupiter has 50 moons! The most well-known are Io (pronounced eye-oh), Europa, and Callisto. Jupiter also has the biggest moon in our solar system, Ganymede. These moons are so big you can see them with just a pair of binoculars. These moons are so big you can see them with just a pair of binoculars.

27. Ganymede is 5262.4 km, or 0.413 Earths wide, making it a little larger than the Earth's moon. It is the largest of Jupiter's moons — in fact it is the largest moon in the solar system.

28. What is the difference between a sun and a planet? …then how can we see the other planets?

29. The sun’s mass is about 750 times greater than the mass of the rest of the solar system combined. It is all relative…

30. SmartStarter – Planets’ Relative Size List the planets from smallest to largest…TWICE Make 2 attempts: 1. Do the best you can from memory 2. Use your Planet table and/or text book to write them in the correct order for sure this time

31. Pla the planets from smallest to largest

32. Distances between objects in the solar system = much larger than distances on Earth. Astronomers often use astronomical units to describe distances within the solar system. One astronomical unit (AU) equals the average distance from Earth to the sun— 149,598,000 kilometers. At its closest point, Pluto is only 29 astronomical units from the Sun (4.4 billion km or 2.75 billion miles).

33. How is the solar system being explored today? Exploring the Solar System Modern technology, including complex telescopes, piloted spacecraft, and space probes, has allowed scientists to explore the solar system.

34. EXPLORING THE SOLAR SYSTEM First Rockets … first rockets powerful enough to escape Earth’s atmosphere and enter space were developed in the 1940s and 1950s. Travel to the Moon… On July 20, 1969,Neil Armstrong, commander of the Apollo 11 spacecraft, became the first person to set foot on the moon. Recent Missions… Scientists have gathered much new information about various planets and moons. A space probe is an unpiloted vehicle that carries scientific instruments into space and transmits information back to Earth. The Hubble Space Telescope has also provided many new views of the solar system and beyond.

35. Space Shuttle - reusable space vehicle that is launched like a rocket but lands like an airplane International Space Station - permanent laboratory designed for research in space. International Space Station

36. 6 Question KAHOOTKAHOOT

37. 25.1 Assessment Questions 1.What two factors combine to keep the planets in orbit around the sun? a.gravity and centripetal force b.gravity and kinetic energy c.gravity and solar wind d.gravity and inertia

38. Assessment Questions 1.What two factors combine to keep the planets in orbit around the sun? a.gravity and centripetal force b.gravity and kinetic energy c.gravity and solar wind d.gravity and inertia ANS:D

39. 2.Which planet has the largest moon relative to the size of the planet? a.Earth b.Mars c.Jupiter d.Saturn 25.1 Assessment Questions

40. Assessment Questions 2.Which planet has the largest moon relative to the size of the planet? a.Earth b.Mars c.Jupiter d.Saturn ANS:A

41. 3.What is a space probe? a.a space mission piloted by humans, such as the International Space Station b.a permanent settlement on the moon or on another planet c.a telescope or other instrument that studies space from an orbit around Earth d.an unpiloted vehicle that carries instruments into space 25.1 Assessment Questions

42. Assessment Questions 3.What is a space probe? a.a space mission piloted by humans, such as the International Space Station b.a permanent settlement on the moon or on another planet c.a telescope or other instrument that studies space from an orbit around Earth d.an unpiloted vehicle that carries instruments into space ANS:D

43. 4. In a heliocentric model, Earth is at the center of the universe, and the sun, moon, and stars move around it. True False 25.1 Assessment Questions

44. Assessment Questions 1.In a heliocentric model, Earth is at the center of the universe, and the sun, moon, and stars move around it. True False ANS:F, geocentric

45. 25.2 THE EARTH-MOON SYSTEM What is wrong with this picture?

46. The earths orbit is not a circle…it is an_____________. Relative size? Relative size

47. Characteristics of Earth’s Moon Atmosphere – Temperature variation Maria, highlands, craters

48. The moon is thought to have formed in a spectacular collision between the early Earth and a Mars-sized object. Formation of the Moon

49. Two different views of the phases of the moon are shown in this diagram. Phases of the Moon

50. Eclipses Solar Eclipse Lunar Eclipse

51. Eclipses occur only at the new moon or the full moon. Eclipses

52. A.During spring tides, the pulls of the moon and sun add together. B.During neap tides, the moon and sun pull Earth and its oceans at right angles. Tides on Earth

53. 25.2 Assessment Questions 1.Why do temperatures on the moon’s surface vary greatly? a.There is no gravity on the moon. b.The moon orbits about Earth. c.The uneven, rocky surface of the moon creates large shadow regions. d.There is no atmosphere on the moon.

54. Assessment Questions 1.Why do temperatures on the moon’s surface vary greatly? a.There is no gravity on the moon. b.The moon orbits about Earth. c.The uneven, rocky surface of the moon creates large shadow regions. d.There is no atmosphere on the moon. ANS:D

55. 2.What are the round impact depressions that cover much of the moon’s surface? a.maria b.craters c.lakebeds d.meteoroids 25.2 Assessment Questions

56. Assessment Questions 2.What are the round impact depressions that cover much of the moon’s surface? a.maria b.craters c.lakebeds d.meteoroids ANS:B

57. 3.What hypothesis about the formation of the moon is supported by much of the data currently available? a.The moon was a large asteroid captured by Earth’s gravity. b.The moon formed when a planet-sized body collided with Earth. c.Internal stresses caused the early Earth to split into the moon and Earth. d.Earth and the moon formed together from a planetary nebula. 25.2 Assessment Questions

58. Assessment Questions 3.What hypothesis about the formation of the moon is supported by much of the data currently available? a.The moon was a large asteroid captured by Earth’s gravity. b.The moon formed when a planet-sized body collided with Earth. c.Internal stresses caused the early Earth to split into the moon and Earth. d.Earth and the moon formed together from a planetary nebula. ANS:B

59. 4. A lunar eclipse can occur when the moon is between the sun and Earth. True False 25.2 Assessment Questions

60. Assessment Questions 4. A lunar eclipse can occur when the moon is between the sun and Earth. True False ANS:F, solar eclipse

61. 25.3 INNER Solar System

62. SMART STARTER What characteristics differ between the inner and outer planets? Bonus: What is wrong with this picture?

63. Characteristics of the Inner Planets - MVEM - Small Dense Rocky

64. Dense – Show me the DATA!

65. Small Relative size of Terrestrial planets (and Pluto)   Relative size of all planets

66. Rocky Terra Terrestrial Planets – similar to Earth’s (“Terra”) structure – Rocky surface – Crust - Mantle - Iron Core

67. PlanetsPlanets PPT Slide Project

68. Mercury

69. Venus

70. Earth

71. Mars

72. Asteroids (ABC)

73. 25.4 OUTER Planets Gas giants….and PlutoPluto

74. Jupiter

75. Saturn

76. Uranus

77. Neptune

78. Kuiper Belt

79. Pluto… Planet OR Dwarf Planet Dwarf Planets = too small to be a planet Dwarf Planets Planet (according to the International Astronomical Union) – In orbit around the sun – Enough gravity to be round – Clear its orbit of smaller objects (Dwarf planets’ gravity are not sufficient to do this…)

81. 25.5 Origin of our Solar System Nebular Theory

82. Formation of the Solar System Any theory to describe the formation of our Solar System must adhere to these facts: 1.Each planet is isolated in space 2.The orbits are nearly circular 3.The orbits of the planets all lie in roughly the same plane 4.The direction they orbit around the Sun is the same as the Sun’s rotation on its axis 5.The direction most planets rotate on their axes is the same as that for the Sun 6.The direction of a planet’s moon orbits is the same as that planet’s direction of rotation 7.The Terrestrial planets are very different from the Jovian planets 8.Asteroids are different from both types of planets 9.Comets are icy fragments that don’t orbit in the ecliptic plane

83. Our sun and the planets began from a cloud of dust and gas (nebula) As the cloud contracts under its own gravity, the Sun is formed at the center. The cloud starts to spin and the smaller it contracts, the faster it spins. Conservation of angular momentum Cloud forms a flattened, pancake shape. Nebular Theory for Solar System formation

84. We’ve seen these disks around other young stars! Beta Pictoris

85. Conservation of Angular Momentum Angular momentum  mass  rotation rate  radius 2

86. Condensation Theory for Planet Formation The gas in the flattened nebula would never eventually clump together to form planets. Interstellar dust (grain-size particles) lies between stars - remnants of old, dead stars. These dust grains form condensation nuclei - other atoms attach to them to start the “collapsing” process to form the planets in the gas cloud.

87. What happened next….. A flattened solar nebula disk exists after cloud spins and contracts Condensation nuclei form clumps that grow into moon-size planetesimals Solar wind from star formation (Sun forming) blow out the rest of the gas Planetesimals collide and grow Planetesimals form the basic planets over hundred million years

88. Why the difference between inner and outer planets? Rocky inner planets: The type of the material that condensed out of the nebular cloud at these higher temperatures was rocky in nature. Gaseous, Bigger outer planets: Both rock and gas could condense out of the cloud at lower temperatures where these planets formed. Rocky inner planets: The type of the material that condensed out of the nebular cloud at these higher temperatures was rocky in nature. Gaseous, Bigger outer planets: Both rock and gas could condense out of the cloud at lower temperatures where these planets formed. Why are they gaseous? - gas is present Why are they bigger? - accretion onto the planet starts sooner because they are further from the Sun, less effected by solar wind TEMPERATURE!

89. Assignment: Read 25.5 Respond to : Write a paragraph or more explaining 1, why the terrestrial planets formed mostly from metal and rock, and not hydrogen and helium like the gas giants, 2 - explain the nebular theory and how our solar system formed. 3- explain why all of the planets revolve around the sun within the same plane and in the same direction.