Question 1

Which of the following best describes the current status of the debate over evidence for life in the Martian meteorite ALH84001?

Accepted Answer

A) Most scientists now agree that the meteorite shows clear evidence of past life on Mars. 
B) Most scientists now agree that the meteorite shows no evidence for past life on Mars. 
C) Most scientists agree that the evidence would support life if the meteorite truly comes from Mars,but few scientists accept that the meteorite is from Mars and instead think it is an ordinary Earth rock. 
D) Most scientists find the evidence intriguing but suspect that it can be explained without requiring past life on Mars. 
A) Most scientists now agree that the meteorite shows clear evidence of past life on Mars. 
B) Most scientists now agree that the meteorite shows no evidence for past life on Mars. 
C) Most scientists agree that the evidence would support life if the meteorite truly comes from Mars,but few scientists accept that the meteorite is from Mars and instead think it is an ordinary Earth rock. 
D) Most scientists find the evidence intriguing but suspect that it can be explained without requiring past life on Mars. D

Question 2

Why do some scientists say that the Moon may have been important for the evolution of human life?

Accepted Answer

A) It created the tides in the ocean,where life most likely started. 
B) It stabilized Earth's axis tilt and prevented large climate changes. 
C) Meteorites from the Moon were the seeds of life on Earth. 
D) It gave humans the inspiration to explore worlds beyond Earth. 
E) It most certainly wasn't-only lunatics would think so. 
A) It created the tides in the ocean,where life most likely started. 
B) It stabilized Earth's axis tilt and prevented large climate changes. 
C) Meteorites from the Moon were the seeds of life on Earth. 
D) It gave humans the inspiration to explore worlds beyond Earth. 
E) It most certainly wasn't-only lunatics would think so. B

Question 3

The analysis of Martian rocks on Earth show that they contain

Accepted Answer

A) tantalizing but unconfirmed hints of life. 
B) bacteria with closely related DNA to bacteria on Earth. 
C) bacteria with very different DNA from bacteria on Earth. 
D) water ice. 
E) chemical byproducts of life. 
A) tantalizing but unconfirmed hints of life. 
B) bacteria with closely related DNA to bacteria on Earth. 
C) bacteria with very different DNA from bacteria on Earth. 
D) water ice. 
E) chemical byproducts of life. A

Question 4

Which of the following is not considered a likely solution to the question of why we are not currently aware of a galactic civilization?

Accepted Answer

A) There is no galactic civilization because civilizations are not common. 
B) There is no galactic civilization because civilizations do not leave their home worlds. 
C) The galactic civilization is deliberately avoiding contact with us. 
D) The galactic civilization probably is undetectable to us because it makes use of technologies that do not obey the known laws of physics. 
E) There is no galactic civilization because most civilizations destroy themselves before achieving interstellar travel. 
A) There is no galactic civilization because civilizations are not common. 
B) There is no galactic civilization because civilizations do not leave their home worlds. 
C) The galactic civilization is deliberately avoiding contact with us. 
D) The galactic civilization probably is undetectable to us because it makes use of technologies that do not obey the known laws of physics. 
E) There is no galactic civilization because most civilizations destroy themselves before achieving interstellar travel.

Question 5

Suppose that Jupiter had never existed,and there was no planet in our solar system between Mars and Saturn.How would we expect this to have affected Earth?

Accepted Answer

A) Earth's orbit would have been unstable,and our planet would have spiraled into the Sun. 
B) There would not have been any effect,since Jupiter is in the outer solar system and Earth is in the inner solar system. 
C) Earth would have been hit by many more comet impacts. 
D) There would be no water on Earth. 
A) Earth's orbit would have been unstable,and our planet would have spiraled into the Sun. 
B) There would not have been any effect,since Jupiter is in the outer solar system and Earth is in the inner solar system. 
C) Earth would have been hit by many more comet impacts. 
D) There would be no water on Earth.

Question 6

Which of the following statements about ozone (in Earth's stratosphere)is not true?

Accepted Answer

A) The presence of ozone was crucial to the origin of life. 
B) If the ozone layer is depleted,we can expect the rate of mutations in land-based life-forms to increase significantly. 
C) Ozone absorbs ultraviolet light from the Sun. 
D) The ozone hole occurring each spring over Antarctica appears to be caused by human-made CFCs. 
A) The presence of ozone was crucial to the origin of life. 
B) If the ozone layer is depleted,we can expect the rate of mutations in land-based life-forms to increase significantly. 
C) Ozone absorbs ultraviolet light from the Sun. 
D) The ozone hole occurring each spring over Antarctica appears to be caused by human-made CFCs.

Question 7

Oxygen did not build up in the atmosphere as soon as life began to produce it because the oxygen was pulled back out of the atmosphere by reactions with surface rocks.

Accepted Answer

A) True 
 B)False

Question 8

The rise of life on the planet Earth some 4 billion years ago was made possible,in part,by the plentiful oxygen in Earth's early atmosphere.

Accepted Answer

A) True 
 B)False

Question 9

Briefly explain the meaning of each term in the equation
Number of Civilizations = Np × flife × fcivilization × fnow.

Accepted Answer

Np is the number of planets in the Milky

Question 10

We have already launched at least four spacecraft that are bound for interstellar space.

Accepted Answer

A) True 
 B)False

Question 11

In the Drake equation (Number of Civilizations = NHP × ( f )life × fcᵢᵥ × fnₒw),we expect the term fcᵢᵥ to be small if

Accepted Answer

A) most civilizations destroy themselves within just a few hundred years of arising. 
B) most of the civilizations that have ever existed are still out and about in the galaxy. 
C) primitive life is common but intelligent life is rare. 
D) most habitable planets never actually get life on them. 
A) most civilizations destroy themselves within just a few hundred years of arising. 
B) most of the civilizations that have ever existed are still out and about in the galaxy. 
C) primitive life is common but intelligent life is rare. 
D) most habitable planets never actually get life on them.

Question 12

Which of the following best explains why an interstellar ramjet could,in theory,achieve continuous acceleration?

Accepted Answer

A) It uses fuel that is more efficient than any other known fuel. 
B) It collects its fuel as it goes,rather than having to carry the weight of fuel along with it. 
C) It takes advantage of theoretically possible loopholes in Einstein's theory of relativity. 
D) It has such a large fuel tank that it will essentially never use up all the fuel it carries. 
E) Its speed always gets faster because the effects of time dilation change the rate at which time flows. 
A) It uses fuel that is more efficient than any other known fuel. 
B) It collects its fuel as it goes,rather than having to carry the weight of fuel along with it. 
C) It takes advantage of theoretically possible loopholes in Einstein's theory of relativity. 
D) It has such a large fuel tank that it will essentially never use up all the fuel it carries. 
E) Its speed always gets faster because the effects of time dilation change the rate at which time flows.

Question 13

The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare.Which of the following statements best sums up the current status of the debate over this hypothesis?

Accepted Answer

A) The debate raged for a while,but is now settled.We are now quite certain that Earth-like planets are common. 
B) The debate raged for a while,but is now settled.We are now quite certain that Earth-like planets are rare. 
C) We do not have enough data to settle the debate,because counterarguments can be made for each argument suggesting Earth-like planets may be rare. 
D) It is no longer discussed,because as part of its broad cover-up of UFOs,the United States government has classified all the material relating to this debate as Top Secret. 
A) The debate raged for a while,but is now settled.We are now quite certain that Earth-like planets are common. 
B) The debate raged for a while,but is now settled.We are now quite certain that Earth-like planets are rare. 
C) We do not have enough data to settle the debate,because counterarguments can be made for each argument suggesting Earth-like planets may be rare. 
D) It is no longer discussed,because as part of its broad cover-up of UFOs,the United States government has classified all the material relating to this debate as Top Secret.

Question 14

According to current science,why didn't oxygen begin to accumulate in the atmosphere for more than a billion years after life appeared on Earth?

Accepted Answer

A) Early forms of animal life consumed the oxygen released by plants during the first billion years of life on Earth. 
B) Early life did not release oxygen,and oxygen releasing organisms didn't evolve for a billion years after the earliest life. 
C) Oxygen was removed from the atmosphere by dissolving in the ocean as quickly as it was released by life. 
D) Oxygen was removed from the atmosphere by chemical reactions with surface rocks as quickly as it was released by life. 
A) Early forms of animal life consumed the oxygen released by plants during the first billion years of life on Earth. 
B) Early life did not release oxygen,and oxygen releasing organisms didn't evolve for a billion years after the earliest life. 
C) Oxygen was removed from the atmosphere by dissolving in the ocean as quickly as it was released by life. 
D) Oxygen was removed from the atmosphere by chemical reactions with surface rocks as quickly as it was released by life.

Question 15

According to fossil evidence,how far back in time did life on Earth exist?

Accepted Answer

A) about 65 million years 
B) about 545 million years 
C) about 2.0 billion years 
D) about 3.5 billion years or more 
A) about 65 million years 
B) about 545 million years 
C) about 2.0 billion years 
D) about 3.5 billion years or more

Question 16

The Voyager I and II spacecraft visited the jovian planets in the 1980s.When will they reach the distance of the nearest stars?

Accepted Answer

A) in our lifetime 
B) in our children's lifetime 
C) in our grandchildren's lifetime 
D) about a hundred thousand years from now 
E) about a million years from now 
A) in our lifetime 
B) in our children's lifetime 
C) in our grandchildren's lifetime 
D) about a hundred thousand years from now 
E) about a million years from now

Question 17

Based on DNA studies,it seems that all life on Earth

Accepted Answer

A) belongs to one of just two kingdoms: plants and animals. 
B) arose from one of five distinct ancestors that lived about two billion years ago. 
C) requires oxygen to survive. 
D) shares a common ancestor. 
A) belongs to one of just two kingdoms: plants and animals. 
B) arose from one of five distinct ancestors that lived about two billion years ago. 
C) requires oxygen to survive. 
D) shares a common ancestor.

Question 18

One idea for interstellar spacecraft involves harnessing energy from nuclear bombs detonated in space.

Accepted Answer

A) True 
 B)False

Question 19

When did the extinction of the dinosaurs occur?

Accepted Answer

A) about 3.5 billion years ago 
B) about 2 billion years ago 
C) 540 million years ago 
D) 65 million years ago 
E) less than 1 million years ago 
A) about 3.5 billion years ago 
B) about 2 billion years ago 
C) 540 million years ago 
D) 65 million years ago 
E) less than 1 million years ago

Question 20

Suppose we discover a "super-Earth" at a distance of 10AU from its star.Should we consider it to be potentially habitable?

Accepted Answer

A) Yes,its atmosphere may contain substantial amounts of greenhouse-type gases that can keep the planet warm beyond the usual boundaries assumed for habitable zones. 
B) Yes,because its host star must be much bigger in order to have a super-Earth,so it will be much hotter there. 
C) No,only planets at approximately 1AU will ever be potentially habitable. 
D) No,greenhouse gases "freeze-out" at those distances. 
A) Yes,its atmosphere may contain substantial amounts of greenhouse-type gases that can keep the planet warm beyond the usual boundaries assumed for habitable zones. 
B) Yes,because its host star must be much bigger in order to have a super-Earth,so it will be much hotter there. 
C) No,only planets at approximately 1AU will ever be potentially habitable. 
D) No,greenhouse gases "freeze-out" at those distances.

Exam 24: Life in the Universe

Which of the following best describes the current status of the debate over evidence for life in the Martian meteorite ALH84001?

Why do some scientists say that the Moon may have been important for the evolution of human life?

The analysis of Martian rocks on Earth show that they contain

Which of the following is not considered a likely solution to the question of why we are not currently aware of a galactic civilization?

Suppose that Jupiter had never existed,and there was no planet in our solar system between Mars and Saturn.How would we expect this to have affected Earth?

Which of the following statements about ozone (in Earth's stratosphere)is not true?

Oxygen did not build up in the atmosphere as soon as life began to produce it because the oxygen was pulled back out of the atmosphere by reactions with surface rocks.

The rise of life on the planet Earth some 4 billion years ago was made possible,in part,by the plentiful oxygen in Earth's early atmosphere.

Briefly explain the meaning of each term in the equation Number of Civilizations = Np × flife × fcivilization × fnow.

We have already launched at least four spacecraft that are bound for interstellar space.

In the Drake equation (Number of Civilizations = NHP × ( f )life × fcᵢᵥ × fnₒw),we expect the term fcᵢᵥ to be small if

Which of the following best explains why an interstellar ramjet could,in theory,achieve continuous acceleration?

The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare.Which of the following statements best sums up the current status of the debate over this hypothesis?

According to current science,why didn't oxygen begin to accumulate in the atmosphere for more than a billion years after life appeared on Earth?

According to fossil evidence,how far back in time did life on Earth exist?

The Voyager I and II spacecraft visited the jovian planets in the 1980s.When will they reach the distance of the nearest stars?

Based on DNA studies,it seems that all life on Earth

One idea for interstellar spacecraft involves harnessing energy from nuclear bombs detonated in space.

When did the extinction of the dinosaurs occur?

Suppose we discover a "super-Earth" at a distance of 10AU from its star.Should we consider it to be potentially habitable?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

Filters