Download Chapter 7 Answer Key 1. i, the Sun and all the bodies

Chapter 7 Answer Key 1. i, the Sun and all the bodies that travel around it
2. a, a relatively small, rocky object that orbits the Sun
3. j, dark areas on the Sun’s surface 4. g, large bodies that revolve around the Sun or another star
5. f, a chunk of matter that enters Earth’s atmosphere and is heated by friction with the air 6. h, Jupiter, Saturn, Uranus, and Neptune 7. c, a huge system of gas, dust, and stars 8. b, a small, orbiting body made of dust, ice, and frozen gases 9. e, the first four planets from the Sun
10. d, the attraction between Earth and objects at or near its surface 11. Nuclear reactions (or nuclear fusion) in the Sun’s core are the source of the Sun’s energy. 12. The Sun and all bodies that orbit the Sun, including planets, dwarf planets, moons, asteroids, comets and meteors make up the solar system. 13. The inner planets include Mercury, Venus, Earth, and Mars. The outer planets include Jupiter, Saturn, Uranus, and Neptune. The inner planets are small and rocky. The outer planets are large and are made up largely of gases. 14. Gravitational attraction between the Sun and the planets keep the planets in their orbits around the Sun. 15. Mars 16. The surface temperature on Venus is much higher than the boiling point of water, so liquid water cannot exist there. 17. Sample answer: Hydrogen is the “fuel” used to generate the Sun’s energy. When the hydrogen is used up, the Sun will move into the Red Giant stage of its life cycle and begin to “die.” 18. Sample answer: Unlike the other outer planets, Pluto is small, icy, and rocky. Its orbit is more elliptical than that of other planets.