Deck 27: Life in the Universe

Question 1

Why is it easier to use Doppler shifts to discover binary stars than to discover planets orbiting other stars?

A)The orbital periods of binary stars are longer than those of planets
B)The Doppler shifts are very small in the case of planets
C)For planets the shifts are so large they shift the lines out of the visible
D)Stars orbited by planets do not generally show spectral lines

Answer 1

The Doppler shifts are very small in the case of planets

Question 2

How are pulsar planets detected?

A)By looking for variations in the light output of the planet.
B)By observing the pulsar planet as tidal forces tear it apart.
C)By looking for shifts in the period of the planets orbit.
D)By observing variations between pulses.

Answer 2

By observing variations between pulses.

Question 3

Why are interstellar signals likely to have narrow bandwidths?

A)The signals will be brighter than with a broader bandwidth
B)It makes it harder to guess the correct frequency
C)It produces more distinct spectral channels for communication
D)Most transmitters only operate over a narrow frequency range

Answer 3

The signals will be brighter than with a broader bandwidth

Question 4

SETI stands for

A)Signal Enhancement Through Interferometry
B)Search for Extraterrestrial Intelligence
C)Satellite Examination of Technological Images
D)Studies of Europa's Tidal Icefields

Question 5

The Drake Equation contains several terms that are known to a high degree of accuracy.

Question 6

Why does the habitable zone shift outward as a star evolves?

A)The star produces more radiation as it ages on the main sequence.
B)The star produces less radiation as it ages on the main sequence.
C)The planets adaptive mechanisms shift toward producing a more habitable environment.
D)The planets adaptive mechanisms shift toward producing a less habitable environment.

Question 7

An organism's characteristics are encoded in its

A)DNA
B)Amino acids
C)Proteins
D)Carbon atoms

Question 8

About what percentage of the planets discovered outside our solar system are giant planets,orbiting close to their parent star?

A)33
B)15
C)55
D)70

Question 9

Which of the following is one of the characteristics of water that make it crucial to terrestrial life?

A)It is tasteless
B)It has a density less than that of mercury
C)It is a very poor solvent
D)It has a large heat capacity

Question 10

Why have few planets with conditions considered habitable have been found so far?

A)Habitable planets are thought to be highly improbable.
B)Terrestrial planets at 1 AU distance are hard to detect with current technologies.
C)Giant planets usually create conditions that are unfavorable for terrestrial planets.
D)Very few solar systems are thought to have had suitable angular momentum to create terrestrial planets.

Question 11

Most of the planets discovered to be orbiting other solar-type stars have masses that are similar to that of

A)The Sun
B)Jupiter
C)Earth
D)The Moon

Question 12

Possible evidence that life once existed on Mars has been discovered.The evidence

A)Was discovered in a meteorite that originated on Mars
B)Was discovered in samples of Mars returned to Earth by a spacecraft
C)Was seen in images of the surface of Mars taken by Global Surveyor
D)Consisted of chlorophyll lines found in spectra of Mars

Question 13

Why is the frequency range between 1 and 10 GHz particularly favorable for interstellar communication?

A)The numbers 1 and 10 are nice round numbers
B)Background noise is at a minimum in that range
C)We have already received signals in that range
D)It is easiest to build radio telescopes that operate in that range

Question 14

About how long does it take radio signals to travel from the Earth to the nearest stars?

A)A few minutes
B)A few weeks
C)A few years
D)A few centuries

Question 15

About what percentage of planets discovered outside our solar system are farther away from their parent star than 1 AU?

A)25
B)35
C)50
D)70

Question 16

The oldest fossils date from about how long after Earth formed?

A)10 million years
B)100 million years
C)1 billion years
D)10 billion years

Question 17

Which strategies have been used to look for interstellar signals?

A)Sweeping the sky alone
B)Pointed observations alone
C)Neither sweeping the sky nor pointed observations
D)Both sweeping the sky and pointed observations

Question 18

Billions of years from now,the habitable zone of the solar system will not include the
Earth but will include

A)Mars
B)Mercury
C)Venus
D)The Moon

Question 19

The habitable zone is defined by what characteristic?

A)Zone where planets of a suitable size to support advanced life are located.
B)Zone where planets of a suitable internal composition to support advanced life are located.
C)Zone where water can exist as a liquid.
D)Zone where X-ray intensity from solar radiation drops below a critical value.