© 2017 Pearson Education, Inc.

Question 1 The Drake equation attempts to define the number of planets in the Milky Way Galaxy. planets with life in the universe. stars with planets like Earth. civilizations in our Galaxy. terrestrial planets with water. Answer: d © 2017 Pearson Education, Inc.

Question 1 The Drake equation attempts to define the number of planets in the Milky Way Galaxy. planets with life in the universe. stars with planets like Earth. civilizations in our Galaxy. terrestrial planets with water. © 2017 Pearson Education, Inc.

Question 2 In the Drake equation, a technical civilization is defined as one that is able to explore space. communicate over interstellar distances. communicate using a written language. construct metal tools. travel at the speed of light. Answer: b © 2017 Pearson Education, Inc.

Question 2 In the Drake equation, a technical civilization is defined as one that is able to explore space. communicate over interstellar distances. communicate using a written language. construct metal tools. travel at the speed of light. © 2017 Pearson Education, Inc.

Question 3 The possibility of life once existing on Mars was supported by the discovery of mudflows and bodies of liquid water existing in the past. water, rather than dry ice, at the south polar cap. the spectral signature of chlorophyll. the face on Mars. volcanoes that are still active. Answer: a © 2017 Pearson Education, Inc.

Question 3 The possibility of life once existing on Mars was supported by the discovery of mudflows and bodies of liquid water existing in the past. water, rather than dry ice, at the south polar cap. the spectral signature of chlorophyll. the face on Mars. volcanoes that are still active. Explanation: The exploration of the Mars rovers Spirit and Opportunity, as well as the Global Surveyor mission, have provided evidence that water did exist on Mars in the past. © 2017 Pearson Education, Inc.

Question 4 The habitable zone is the area where temperatures on a planet are reasonable. terrestrial planets can form around a star. terrestrial planets could have liquid water on their surfaces. liquid water can condense into rain in the atmosphere. Sun-like stars can exist in the Milky Way Galaxy. Answer: c © 2017 Pearson Education, Inc.

Question 4 The habitable zone is the area where temperatures on a planet are reasonable. terrestrial planets can form around a star. terrestrial planets could have liquid water on their surfaces. liquid water can condense into rain in the atmosphere. Sun-like stars can exist in the Milky Way Galaxy. Explanation: Habitable zones have the right temperature for life—neither too hot nor too cold. Habitable zones must be smaller and closer to a cool star like the Sun because such a star emits less warming radiation. © 2017 Pearson Education, Inc.

Question 5 Which star is the best candidate for seeking extraterrestrial life? Spica, a B-type main-sequence star 61 Cygni, a K-type main-sequence star Sirius B, a white dwarf Antares, an M-type supergiant Barnard’s star, an M-type red dwarf Answer: b © 2017 Pearson Education, Inc.

Question 5 Which star is the best candidate for seeking extraterrestrial life? Spica, a B-type main-sequence star 61 Cygni, a K-type main-sequence star Sirius B, a white dwarf Antares, an M-type supergiant Barnard’s star, an M-type red dwarf Explanation: In the OBAFGKM spectral ranking scale, K-type main-sequence stars are cooler than the Sun, but will shine long enough with nonlethal radiation to allow life to form and evolve. © 2017 Pearson Education, Inc.

Question 6 The “water hole” is a region in radio light where natural emissions from our Galaxy are minimal. on Mars where liquid water has been proven to exist in the past. on the Moon where water is believed to exist under ice in a deep crater. in the Oort cloud where comets rich in water are formed. Answer: a © 2017 Pearson Education, Inc.

Question 6 The “water hole” is a region in radio light where natural emissions from our Galaxy are minimal. on Mars where liquid water has been proven to exist in the past. on the Moon where water is believed to exist under ice in a deep crater. in the Oort cloud where comets rich in water are formed. Explanation: The “water hole” may be the best part of the electromagnetic spectrum for intelligent civilizations to communicate across the vast reaches of space. © 2017 Pearson Education, Inc.

Question 7 An extremophile is an extremely unlikely place to search for life. a planet that has very extreme temperatures. a planet whose orbit lies beyond Pluto in the most distant regions of our solar system. a life-form adapted to very extreme environments. Answer: d © 2017 Pearson Education, Inc.

Question 7 An extremophile is an extremely unlikely place to search for life. a planet that has very extreme temperatures. a planet whose orbit lies beyond Pluto in the most distant regions of our solar system. a life-form adapted to very extreme environments. © 2017 Pearson Education, Inc.