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Unit 2: The Solar System Mrs. Williams 8 th Grade.

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1 Unit 2: The Solar System Mrs. Williams 8 th Grade

2 The Big Idea Planets and a variety of other bodies form a system of objects orbiting the sun.

3 The Center of the Solar System Unit 2 Lesson 1 Historical Models of the Solar System Solar system - the sun & all of the bodies that orbit the sun. Heliocentric model – Sun centered, Earth and the other planets orbit the sun. Geocentric model – Earth centered, the sun, moon and planets circling the Earth

4 In the beginning… Aristotle ( BCE)- believed in a geocentric model, part of his logic was that we could feel no motion on Earth, so Earth couldn’t be moving. He thought we should detect a shift in position between nearby stars and far away ones. Parallax- apparent shift in the position of an object wen viewed from different locations. Unit 2 Lesson 1 Historical Models of the Solar System

5  Aristarchus (about BCE)- proposed a heliocentric model, his attempts to measure relative distances to moon & sun have been major contribution to science Unit 2 Lesson 1 Historical Models of the Solar System

6 Ptolemy- ( CE) believed in a geocentric model. His model was used for 14 centuries. Planets moved on small circles that in turn moved on larger circles (“wheels-on-wheels”) Allowed people to predict the motions of planets years into the future. Unit 2 Lesson 1 Historical Models of the Solar System

7 Copernicus- ( ) believed in a heliocentric model with perfect circles Kepler- ( ) Realized that planetary orbits were not circular but were more like ellipses. Unit 2 Lesson 1 Historical Models of the Solar System

8 Galileo Galilei ( )  Improved the telescope in 1609  Observed Jupiter’s moons, Io, Europa, Callisto, and Ganymede which gave support of heliocentric model  Observed Venus’s phases Unit 2 Lesson 1 Historical Models of the Solar System

9  Gravity - force of attraction between objects that is due to their masses & the distances between them.  Every object in the universe pulls on every other object.  Orbit - path that a body follows as it travels around another body in space. Unit 2 Lesson 2 Gravity & the Solar System

10 Kepler’s Three Laws 1. Planetary orbits are ellipses with the sun at one focus Aphelion- where the object is farthest from the sun. Perihelion - where the object is closest to the sun. 1. Planets move faster in their orbits when they are closer to the sun. 2. Distance of a planet from the sun to the time the planet takes to go once around its orbit. Unit 2 Lesson 2 Gravity & the Solar System

11 Law of Gravitational Force Law of universal gravitation- states that all objects in the universe attract each other through gravitational force. Centripetal force -inward force that causes an object to move in a circular path.  When planets orbit the sun, a force similar to centripetal force prevents them from moving out of their orbits and into a straight line.  The sun’s gravity is the force that keeps the planets moving in orbit around the sun. Unit 2 Lesson 2 Gravity & the Solar System

12 How the Solar System Formed Theory Solar Nebula - inward pull of gravity is balanced by the outward push of gas pressure in the cloud (perhaps the explosion of a nearby star) Planetesimals - Collisions between these bodies formed larger bodies from which planets formed

13 Here Comes the Sun Corona-outer atmosphere of the sun (up to 2,000,000 ˚C) Chromosphere- middle layer of sun’s atmosphere (6,000 ˚C) Photosphere- visible surface of the sun. Energy escapes into space (5,527 ˚C) Unit 2 Lesson 3 The Sun

14 Convective Zone – energy travels by convection from the radiative zone to the photosphere Radiative Zone - energy is transferred away from the core by radiation. Core – very dense center of sun. Temperature of 15,000,000 ˚ C, where nuclear fusion occurs. Unit 2 Lesson 3 The Sun

15 Solar Activity  Sunspots-dark areas that form on the surface of the sun. Unit 2 Lesson 3 The Sun  Solar flare – an explosive release of energy that can extend outward as far as the sun’s outer atmosphere  Prominence- huge loops of relatively cool gas that extend outward from the photosphere

16 - process by which two or more low- mass atomic nuclei fuse to form another, heavier nucleus. Nuclear Fusion - process by which two or more low- mass atomic nuclei fuse to form another, heavier nucleus. Three Steps of Nuclear Fusion in the Sun 1. Deuterium - 2 H + collide (1 P, 1 N- a heavy hydrogen) 2. Helium-3 – deuterium combines w/ another H + (more energy/ gamma rays released) 3. Helium-4 – 2 He-3 nuclei combine to form He-4 (more energy/pair of H+ released) turn to pgs Unit 2 Lesson 3 The Sun

17 Mixing It Up  By Radiation – energy leaves the core in the form of electromagnetic waves  By Convection – energy (heat) is transferred by the circulation or movement of matter Unit 2 Lesson 3 The Sun

18 Extreme to the Core Unit 2 Lesson 4 The Terrestrial Planets Terrestrial planets - the four small, dense, rocky planets that orbit closest to the sun astronomical unit (AU) - average distance between the sun & Earth, or approximately 150 million km.

19 Mercury  Period of Rotation-last almost 59 Earth days  Period of revolution-88 days  Temps range from - 184˚C to 427˚C  Smallest planet with craters Venus Retrograde rotation (clockwise) Rotation- 243 Earth days Revolution- 225 days Temp- 465 ˚C; CO 2 traps the sun’s energy Thousands of volcanoes & craters Sulfuric acid rain Unit 2 Lesson 4 The Terrestrial Planets

20 Earth  Only planet that supports life  Liquid water, energy soursce  Atmosphere contains O 2  Only planet divided into tectonic plates Mars Rotation- 24 h 37 min Revolution Earth years Olympus Mons- largest volcano/mtn in solar system Valles Marineris – longest canyon in solar system Thin CO 2 atmosphere Unit 2 Lesson 4 The Terrestrial Planets

21 A Giant Among Giants! Gas giants have deep, massive gas atmospheres, made up mostly of hydrogen & helium. No surface to stand on. Large and cold. Unit 2 Lesson 5 The Gas Giant Planets

22 Jupiter  Rotates fastest – 9 h 55 min  Revolution– Earth years  Great Red Spot  63 moons  Io  Europa  Callisto  Ganymede Saturn Rotation- 10 h 39 min Revolution years Planetary ring system Made of H + & He 60 moons Enceladus Titan Unit 2 Lesson 5 The Gas Giant Planets

23 Uranus  Rotation- 17 h 24 min  Revolution-84 years  Made of H + & He  Atmosphere of methane  Tilted on its side as it orbits the sun  27 moons  Miranda Neptune Rotation-16 h 7 min Revolution years H + /He and methane Great dark spot 13 moons Triton-orbits opposite Unit 2 Lesson 5 The Gas Giant Planets

24 Small Bodies in the Solar System  dwarf planets- celestial body that orbits the sun, is round because of its own gravity.  Ceres (between Mars & Jupiter)  Pluto  Haumea  Makemake  Eris

25 Kuiper Belt- orbits just beyond Neptune  Kuiper belt object (KBO) -any of the minor bodies in the Kuiper belt. They are made of methane ice, ammonia ice, and water ice.

26 Comets  Comet -small body of ice, rock, & dust that follows a highly elliptical orbit around the sun.  Oort cloud - spherical region tht surrounds the solar system

27 On the Rocks  Asteroid – small, irregularly shaped, rocky object that orbits the sun.  Most located in the asteroid belt between the orbits of Mars and Jupiter  Some are rich in carbon, others rocky with cores or iron and nickel

28 Burned Out  Meteoroid -rocky body, ranging in size from that of a sand grain to that of a boulder, which travels through space.  Meteor -bright streak of light that results when a meteoroid burns up in Earth’s atmosphere.  Meteorite - a meteoroid that reaches Earth’s surface without burning up.


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