UniverseTenth Edition

Chapter 27The Search for Extraterrestrial Life

Roger Freedman • Robert Geller • William Kaufmann III

Clicker Questions

Life is based on molecules containing carbon. This is thought to be so because carbonA. is the most versatile of elements in

forming bonds. B. is the most abundant element in our solar

system. C. forms bonds that can only be destroyed at

very high temperatures. D. only bonds to oxygen.E. is an element formed in the Sun.

Q27.1

Life is based on molecules containing carbon. This is thought to be so because carbonA. is the most versatile of elements in

forming bonds. B. is the most abundant element in our solar

system. C. forms bonds that can only be destroyed at

very high temperatures. D. only bonds to oxygen.E. is an element formed in the Sun.

A27.1

The conditions required to produce amino acids, the fundamental building blocks of life, from simple elements and moleculesA. have not yet been reproduced. B. have been reproduced in the laboratory under

extreme conditions that did not exist on Earth in the past.

C. have been reproduced in the laboratory under conditions that probably existed on Earth in the past.

D. have been proven to exist only in outer space, implying that only meteors could have brought amino acids to Earth. Q27.2

The conditions required to produce amino acids, the fundamental building blocks of life, from simple elements and moleculesA. have not yet been reproduced. B. have been reproduced in the laboratory under

extreme conditions that did not exist on Earth in the past.

C. have been reproduced in the laboratory under conditions that probably existed on Earth in the past.

D. have been proven to exist only in outer space, implying that only meteors could have brought amino acids to Earth. A27.2

Liquid water is crucial for life. Astrobiologists want to know where else in our solar system liquid water may have existed. We now think it is likely that liquid water has existed on

A. Mars and Venus. B. Mars and Europa. C. Europa and Titan. D. Mercury and the

Moon.E. Mars and the Moon

Q27.3

Liquid water is crucial for life. Astrobiologists want to know where else in our solar system liquid water may have existed. We now think it is likely that liquid water has existed on

A. Mars and Venus. B. Mars and Europa. C. Europa and Titan. D. Mercury and the

Moon.E. Mars and the Moon

A27.3

Mercury, Venus, and the Moon are considered unlikely places to search for life because

A. their surfaces have all been explored and no fossils were found.

B. there is no water in solid, liquid, or gas form on any of them.

C. on these worlds conditions have not existed for water to be in liquid form for any significant length of time.

D. we know that no carbon exists on these worlds.E. the solar wind would sterilize their surfaces.

Q27.4

Mercury, Venus, and the Moon are considered unlikely places to search for life because

A. their surfaces have all been explored and no fossils were found.

B. there is no water in solid, liquid, or gas form on any of them.

C. on these worlds conditions have not existed for water to be in liquid form for any significant length of time.

D. we know that no carbon exists on these worlds.E. the solar wind would sterilize their surfaces.

A27.4

This structure on the surface of Mars A. is a face-like structure made by aliens.

B. was caused by tidal forces.

C. is a feature of natural origin within a 215-km wide crater.

D. is the result of digging by a Viking lander.

E. is of unknown cause.

Q27.5

This structure on the surface of Mars A. is a face-like structure made by aliens.

B. was caused by tidal forces.

C. is a feature of natural origin within a 215-km wide crater.

D. is the result of digging by a Viking lander.

E. is of unknown cause.

A27.5

How are we most likely to learn that life exists somewhere outside our solar system?A. Aliens, most likely Klingons or Vulcans, will visit

us. B. We will pick up radio signals from aliens. C. We will find alien artifacts when we eventually

visit other solar systems. D. Remote controlled spacecraft from alien worlds

will visit us. E. Ancient Egyptian stone tablets will reveal Ra

was actually the leader of a superior alien race that populated Earth.Q27.6

How are we most likely to learn that life exists somewhere outside our solar system?A. Aliens, most likely Klingons or Vulcans, will visit

us. B. We will pick up radio signals from aliens. C. We will find alien artifacts when we eventually

visit other solar systems. D. Remote controlled spacecraft from alien worlds

will visit us. E. Ancient Egyptian stone tablets will reveal Ra

was actually the leader of a superior alien race that populated Earth.A27.6

A. search for Earth-sized planets by looking for their transit in front of a nearby star.

B. look for a small wobble in the position of a star indicating a planet is in orbit around it.

C. use its very high resolution to attempt to photograph planets.

D. look for an infrared signal from nearby stars to determine if a planet is present.

E. listen for radio signals from nearby stars.Q27.7

The Kepler telescope was placed in orbit in 2009. Its task was to

The Kepler telescope was placed in orbit in 2009. Its task was to

A. search for Earth-sized planets by looking for their transit in front of a nearby star.

B. look for a small wobble in the position of a star indicating a planet is in orbit around it.

C. use its very high resolution to attempt to photograph planets.

D. look for an infrared signal from nearby stars to determine if a planet is present.

E. listen for radio signals from nearby stars.A27.7

The Drake equation allows us to A. calculate exactly how many civilizations exist in our Galaxy.

B. estimate very roughly how many civilizations exist in our Galaxy.

C. determine which stars might have planets in orbit around them with a developed civilization.

D. estimate the number of aliens in a civilization.

E. estimate the distance to the nearest alien civilization.

Q27.8

The Drake equation allows us to A. calculate exactly how many civilizations exist in our Galaxy.

B. estimate very roughly how many civilizations exist in our Galaxy.

C. determine which stars might have planets in orbit around them with a developed civilization.

D. estimate the number of aliens in a civilization.

E. estimate the distance to the nearest alien civilization.

A27.8

Planets in orbit around a low-mass star are unsuitable for life becauseA. the planet cannot get close enough to the

star to be warm enough for liquid water to exist.

B. the planet would have to be so close to the star that tidal forces would keep one face of the planet toward the star.

C. low-mass stars have a very short lifetime.D. carbon would not be produced in the star. E. such planets cannot have an atmosphere. Q27.9

Planets in orbit around a low-mass star are unsuitable for life becauseA. the planet cannot get close enough to the

star to be warm enough for liquid water to exist.

B. the planet would have to be so close to the star that tidal forces would keep one face of the planet toward the star.

C. low-mass stars have a very short lifetime.D. carbon would not be produced in the star. E. such planets cannot have an atmosphere. A27.9

Planets in orbit around a high mass star are unsuitable for life because

A. the planet would be so hot that liquid water could not exist.

B. strong tidal forces would keep one face of the planet towards the star.

C. high mass stars have very short lifetimes. D. the star would not make carbon.E. such planets cannot have an atmosphere.

Q27.10

Planets in orbit around a high mass star are unsuitable for life because

A. the planet would be so hot that liquid water could not exist.

B. strong tidal forces would keep one face of the planet towards the star.

C. high mass stars have very short lifetimes. D. the star would not make carbon.E. such planets cannot have an atmosphere.

A27.10