1. Practice Test Chapter 15

2. The Sun, planets and their moons, and a large collection of smaller objects such as asteroids, comets, and meteors are, together, called the: A. universe. B. galaxy. C. solar system. D. nebulae.

3. A unit used to measure long distances, equivalent to the distance from the Sun to Earth, is known as the: a.light year. b.cosmic scale. c.astronomical unit. d.sidereal year.

4. Terrestrial planets include all of the following EXCEPT: a.Mercury. b.Venus. c.Earth. d.Jupiter.

5. The gas planets include all of the following EXCEPT: a.Jupiter. b.Venus. c.Saturn. d.Uranus.

6. All of these objects in the night sky are seen because they reflect light EXCEPT: a.Earth’s moon. b.Venus. c.stars. d.Mercury.

7. A “shooting star” is seen when this object enters Earth’s atmosphere and is vaporized: a.a comet. b.a planetary satellite. c.an asteroid. d.a meteor.

8. Of the planets shown, the one which requires the longest time for one revolution of the sun is: Of the planets shown, the one which requires the longest time for one revolution of the sun is: a.Mars. a.Mars. b.Venus. b.Venus. c.Earth. c.Earth. d.Mercury. d.Mercury.

9. The force of gravity between two objects will be greatest if their masses are: a.small and they far apart. b.large and they are close together. c.large and they are far apart. d.small and they are close together.

10. The asteroid belt is located between the planets: a.Mercury and Venus. b.Earth and Mars. c.Mars and Jupiter. d.Saturn and Uranus.

11. The diagram which best represents the comparison between the diameters of the moon and Earth is: The diagram which best represents the comparison between the diameters of the moon and Earth is: A. 1 A. 1 b.2 b.2 c.3 c.3 d.4 d.4

12. It would be difficult to live on the moon because it lacks all of the following EXCEPT: a.air. b.water. c.gravity. d.normal temperatures.

13. Practice Test Chapter 16

14. The phrase “a giant, hot ball of gases” best describes a: a.planet. b.moon. c.star. d.meteorite.

15. The source of the Sun’s heat and light energy is: a.combustion of helium gas. b.fusion of hydrogen nuclei. c.gravitational pressure. d.burning of fossil fuels.

16. The main characteristics used to classify stars include all of the following EXCEPT: a.shape. b.brightness. c.color. d.temperature.

17. The color of the hottest stars is: a.red. b.orange. c.yellow. d.blue.

18. By size, the star known as our Sun is classified as: a.supergiant. b.giant. c.average. d.dwarf.

19. Scientists measure distances beyond our solar system (such as the distance between two stars) using these units: a.meters b.kilometers c.astronomical units d.light years

20. According to the H-R diagram in Figure 16- 1A, the areas labeled B and E would be classified as: According to the H-R diagram in Figure 16- 1A, the areas labeled B and E would be classified as: a.red and blue supergiants a.red and blue supergiants b.the main sequence. b.the main sequence. c.white dwarfs. c.white dwarfs. d.red giants. d.red giants.

21. According to the H-R diagram in Figure 16- 1A, the areas labeled C and D would be classified as: According to the H-R diagram in Figure 16- 1A, the areas labeled C and D would be classified as: a.red and blue supergiants. a.red and blue supergiants. b.white dwarfs. b.white dwarfs. c.the main sequence. c.the main sequence. d.red giants. d.red giants.

22. As a group, stars known as main sequence stars on an H-R diagram are best described as being: As a group, stars known as main sequence stars on an H-R diagram are best described as being: a.hotter. a.hotter. b.larger. b.larger. c.stable. c.stable. d.brighter. d.brighter.

23. The explosion of a very large star is known as a: a.black hole. b.white dwarf. c.neutron star. d.supernova.

24. A star begins to form when gravitational forces cause denser regions of a huge cloud of gas and dust to collapse. The earliest stage of a star’s life cycle is called the: a.protostar. b.red giant. c.white dwarf. d.supernova.

25. When the core of a star runs out of hydrogen: a.nuclear fusion stops and the star stops producing light. b.the core contracts, raising the temperature so that other fusion reactions occur. c.the star is immediately crushed into a black hole. d.the star becomes a white dwarf and then a red giant.

26. Chapter 16 Math Problems

27. Sirius is about 8.8 light years from Earth. If one light year equals 9.46 ´ 10 12 kilometers, how far is Sirius from Earth, measured in kilometers? a.8.3 ´ 10 13 kilometers b.1.1 ´ 10 13 kilometers c.8.3 ´ 10 11 kilometers d.1.1 ´ 10 11 kilometers

28. The distance from Earth to the star Proxima Centauri is 4.01 ´ 10 13 kilometers. What is this distance in light years? One light year is equal to 9.46 ´ 10 12 kilometers. a.0.424 light years b.4.24 light years c.42.4 light years d.424 light years

29. If you were traveling at 30 kilometers per second, how long would it take to reach Proxima Centauri, the nearest star to Earth other than our Sun? Proxima Centauri is 4.01 ´ 10 13 kilometers from Earth. Hint: there are 31,557,600 seconds in one year. a.Approximately 134 years b.Approximately 4,240 years c.Approximately 42,400 years d.Approximately 1,340,000,000,000 years