Earth Science 11 Chapter 28 Answers

Earth Science 11 Chapter 28 Answers: 28.1 1. All are forms of electromagnetic radiation 2. A spectroscope separates visible light into its component colors 3. Scientists compare the dark lines in the stars absorption spectra with the colored lines in the emission spectra of various elements. If the lines match, those elements are found in the star’s atmosphere. 4. Because the objects are moving, the wavelength of the light decreases if the objects are moving toward the observer (blueshift) or increases if the objects are moving away from the observer (redshift). 5. It suggests that the atmosphere of each star has a unique combination of elements. 28.2 1. Galaxies are natural groupings of stars in space, whereas constellations are not. A constellation is a group of stars that appear to be together as viewed from Earth. 2. A light-year is the distance a ray of light travels in one year, equal to 9.5 x 1012 kilometers. A parsec equals 3.258 light years, or 3.086 x 1013 kilometers. 3. Second row – Temperature, Composition Third row – Luminosity 4. The coolest stars are red. As star surface temperature increases, star color changes to orange, then yellow, and then white. The hottest stars are bluish-white. 5. The sun would be more luminous in both cases because a star’s luminosity depends on its temperature and size. 6. Stars with apparent magnitude differing by 5 differ in brightness by a factor of 100. Thus, a star that has an apparent magnitude that is larger by 10 (11.5 – 1.5) Is approximately 10 000 times dimmer (100 x 100). 28.3 1. The Hertzsprung-Russell diagram is a plot of star luminosity against star surface temperature and depicts the stages in the life cycle of stars. 2. The force of gravity balances the force of energy from fusion. 3. When a massive star runs low on hydrogen, heavier elements begin to fuse until eventually they produce iron nuclei. The star swells to more than 100 times the diameter of the sun, becoming a supergiant. Because the formation of iron nuclei absorbs energy, the iron core of the star suddenly collapses, creating a shock wave that blasts the layers into space in a brilliant burst of light called a supernova. Left behind is a black hole (if the original star was at least 15 times more massive than the sun), or a neutron star. 4. It is unlikely that a star with 10 times the sun’s mass will live long enough to allow organisms on an orbiting planet to evolve into complex forms. 28.4 1. The universe includes everything that exists; the observable universe includes only that which we can observe. The observable universe is limited in size by a combination of the age of the universe, and the speed of light. 2. Most galaxies are either spiral or elliptical. 3. The total energy emitted by a normal galaxy equals the sum of the energy emitted by its component stars. An active galaxy emits far more energy than the sum of energy emitted by its component stars. Active galaxies emit large amounts of energy and/or are highly variable and change in brightness over a short period. 4. From top: Observable universe, Virgo Cluster; from left Comets, Planets, Sun, Asteroids, Meteoroids. 5. Light from distant galaxies takes a very long time to reach Earth. Thus, the more distant the galaxy, the earlier in time we are seeing it. These observations support the big bang model because they suggest that galaxies have evolved through time as the universe has expanded and that the galaxies formed at nearly the same time. Chapter Review – pages 638/9 1. An astronomical unit is the average distance from Earth to the sun; a light-year is the distance light travels in a year. 2. Absolute magnitude is a measure of stars’ brightness if they were all equidistant from Earth; apparent magnitude is how bright stars would appear when viewed from Earth. 3. A pulsar is a neutron star that is spinning very rapidly; a quasar is a type of active galaxy. 4. Giant stars have diameters 10 – 100 times greater than that of the sun, while supergiants have diameters more than 100 times that of the sun. 5. A supernova is the burst of light that results from the sudden collapse of the iron core of a massive star; a neutron star is the superdense mass of neutrons that can result after the collapse of a massive star. 6. A constellation is a perceived pattern in a random group of stars; a galaxy is an actual grouping of stars. 7. A nebula is a cloud of gas and dust; a planetary nebula is the layers of brightly glowing gases around a white dwarf. 8. A white dwarf is the glowing stellar core of a star near the end of the star’s life; a black nole is the remnant of a star at least 15 times as massive as the sun. 9. The electromagnetic spectrum is the full range of wavelengths of electromagnetic radiation; the continuous spectrum is the visible-light portion of the electromagnetic spectrum. 10. A neutron star is the remnant of massive star that had become a supernova; a main-sequence star is actively fusing hydrogen into helium. 11. An emission spectrum shows the wavelengths of visible light that a glowing gas emits; an absorption spectrum shows which wavelengths of visible light a cooler gas absorbs. 12. Matter must be available in the form of a cloud of gases and dust (a nebula). Then there must be a force that causes the nebula to condense and contract so that a fusion reaction can take place. 13. Each star contains different amounts of various elements. 14. As the star moves, the wavelengths of the light it emits change, shifting toward the blue end of the spectrum if the star is moving toward Earth and toward the red end if it is moving away from Earth. 15. The hottest stars are bluish-white; the coolest stars are reddish. Stars with ‘in-between’ temperatures are white, yellow, and orange. 16. The Big Dipper is part of the constellation Ursa Major. Other bright constellations you may find are Cassiopeia, Pegasus, and Cygnus. 17. Some possible answers: Apparent Magnitude – depends on star’s absolute magnitude and distance from earth Absolute Magnitude – Depends on star’s size and temperature For both: both are measures of star brightness and the lower the number, the brighter the star. 18. Fusion in a massive star forms iron nuclei. The iron core collapses, and a shock wave results. 19. The star’s position will move from the main sequence into the area of the red giants, and then will move to the lower left as it becomes a dwarf star. 20. Yes, the sun’s absolute magnitude is +4.8, and its apparent magnitude is +4.8. We can see stars of that magnitude without a telescope. 21. The planets’ proximity to Earth makes them appear brighter. 22. Large-mass stars have relatively short lifespans, and end in supernovae, whereas small-mass stars have longer lifespans and end as white dwarfs. 23. 1000 parsecs 24. 25 25. 100 000 parsecs 26. -3 27. 100 parsecs