Study Notes for Chapter 30: Stars, Galaxies, and the Universe

1 A galaxy is made of stars, dust, and gas bound together by ______. A galaxy is made of stars, dust, and gas bound together by ______. gravity gravity

2 A large, bright star whose hot core has used most of its hydrogen is a _____. A large, bright star whose hot core has used most of its hydrogen is a _____. giant giant

3 A light-year is the distance ____ travels in a year. A light-year is the distance ____ travels in a year. light light

4 A small, hot, extremely dense core left after a star collapses is a _____ dwarf. A small, hot, extremely dense core left after a star collapses is a _____ dwarf. white white

5 A star moving away from the Earth has a spectrum that is shifted toward ______. A star moving away from the Earth has a spectrum that is shifted toward ______. red red

6 A star with the sun’s mass would stay on the _____ sequence of the H-R diagram for about 10 billion years. A star with the sun’s mass would stay on the _____ sequence of the H-R diagram for about 10 billion years. main main

7 A white ______ is a hot, extremely dense core of matter left after a star _______. A white ______ is a hot, extremely dense core of matter left after a star _______. dwarf dwarf collapses collapses

8 About ______ stars are visible from Earth without a telescope. About ______ stars are visible from Earth without a telescope. 6,000 6,000

9 ______ magnitude is the true brightness of a star. ______ magnitude is the true brightness of a star. Absolute Absolute

10 After its temperature rises to 10,000,000°C, a _____ becomes a star when nuclear fusion begins. After its temperature rises to 10,000,000°C, a _____ becomes a star when nuclear fusion begins. protostar protostar

11 _______ magnitude is the brightness of a star as it appears from Earth. _______ magnitude is the brightness of a star as it appears from Earth. Apparent Apparent

12 Astronomers believe that cosmic background _______ formed shortly after the big bang. Astronomers believe that cosmic background _______ formed shortly after the big bang. radiation radiation

13 By analyzing the light that a star emits, astronomers can determine the ______ and ________ of a star. By analyzing the light that a star emits, astronomers can determine the ______ and ________ of a star. composition composition temperature temperature

14 During the main sequence stage, ______ fuses into ______ to generate energy in a star’s core. During the main sequence stage, ______ fuses into ______ to generate energy in a star’s core. hydrogen hydrogen helium helium

15 Hubble’s discovery that there was ____ shift in the spectra of galaxies lead to an understanding that the universe is ____. Hubble’s discovery that there was ____ shift in the spectra of galaxies lead to an understanding that the universe is ____. red red expanding expanding

16 Many astronomers believe that black _____ do not exist. Many astronomers believe that black _____ do not exist. dwarfs dwarfs

17 Most of the universe is made of _____ energy and dark _______. Most of the universe is made of _____ energy and dark _______. dark dark matter matter

18 Red shift in the spectra of galaxies told ______ that the universe is expanding. Red shift in the spectra of galaxies told ______ that the universe is expanding. Hubble Hubble

19 Scientists determine the composition and temperature of stars by analyzing the ________ of the light that stars emit. Scientists determine the composition and temperature of stars by analyzing the ________ of the light that stars emit. spectra spectra

20 Stars _____ to move in the sky because ______ is moving. Stars _____ to move in the sky because ______ is moving. appear appear Earth Earth

21 The ____ bang occurred about __ billion years ago. The ____ bang occurred about __ billion years ago. big big 14 14

22 The ____ stars are ____ in color, the hottest stars are _____. The ____ stars are ____ in color, the hottest stars are _____. coolest coolest red red blue blue

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