Question 1

Which of the following is a good summary of what most astronomers think about UFO reports in the popular media?
A) so far there is no scientific evidence that UFO's have anything to do with life outside the Earth
B) it is now clearly established that alien spacecraft have crashed on Earth; we have the bodies of the aliens who flew them here
C) while no UFO's have landed, we have overheard communications between them with our radio surveys and thus have evidence that there are intelligent creatures aboard them
D) UFO's are now known to come from the planet Mars, the only other planet that we know has life on it
E) UFO's have kidnapped a number of Earth inhabitants, including at least one well-known astronomer; her reports convinced other scientists that UFO's are indeed alien spaceships

Accepted Answer

Most astronomers believe that there is currently no scientific evidence to support claims of UFOs being related to extraterrestrial life, despite popular media reports.

Question 2

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is
A) the speed of sound (the natural speed for messages)
B) the speed of light
C) the speed of the Voyager spacecraft (which is typical of our space probes)
D) instantly (as fast as we want) -- if we only knew where they were located
E) the orbital speed of the Earth

Accepted Answer

The fastest speed at which we can communicate with other civilizations is the speed of light, which is the universal speed limit. Any signals or messages we send out into space travel at this speed, and so would take thousands, if not millions, of years to reach any potentially inhabited planets.

Question 3

Which of the following is a biomarker that could be used from an observatory around a nearby star, with the right equipment, to identify the Earth as a planet with life:
A) the presence of a large moon around the Earth
B) free oxygen in the Earth's atmosphere
C) the abundance of micro-organisms in the deserts of the Earth
D) the fact that most of our atmosphere is made of nitrogen
E) ice in the Earth's polar caps
Section 30.4: The Search for Extraterrestrial Intelligence

Accepted Answer

Free oxygen in the Earth's atmosphere is a strong indication of photosynthetic life, making it a biomarker that could be detected by observing the Earth from a distance with the right instruments. The other answer options are not necessarily indicative of life and would not be useful as biomarkers.

Question 4

Which of the following questions is NOT part of what astronomers call the "cosmic haystack problem" in receiving messages from other civilizations in space?
A) we don't know what star might have planets with intelligent life
B) we don't know what channel they may be using to send messages
C) we don't know whether the signal is always on (continuous) or only for a brief time every cycle
D) we don't know how to receive signals in the wavelength range that is the most likely for interstellar communications
E) we don't know how other civilizations might encode messages in the carrier wave they send

Accepted Answer

The question referring to wavelength range is not typically included in the "cosmic haystack problem," which specifically refers to the challenges of finding and detecting signals among a vast number of candidates. The other four questions are commonly included in this problem.

Question 5

Which of the following events in cosmic history is the most recent?
A) the birth of the universe
B) the formation of our Galaxy
C) the formation of the Sun
D) the formation of life on Earth
E) you can't fool me, all of the above happened at roughly the same time

Accepted Answer

The formation of life on Earth is the most recent event among the given options. The birth of the universe (Big Bang) happened approximately 13.8 billion years ago, followed by the formation of our Galaxy (Milky Way) about 10 billion years ago, and the formation of the Sun and the solar system about 4.6 billion years ago. The earliest evidence of life on Earth dates back to about 3.8 billion years ago, which makes it the most recent event among the options.

Question 6

What makes the Earth different from the other worlds that might have life in the solar system (and easier to detect from far away) is that only Earth
A) has liquid water on it; no other world in our solar system has water
B) has temperatures in some places where chemical change is possible
C) has a solid surface
D) has a biosphere on its surface where photosynthesis can take place
E) has the chemical ingredients from which life might begin

Accepted Answer

Earth's biosphere, where photosynthesis occurs, significantly alters its atmosphere in ways detectable from afar, making it distinct in the search for life.

Question 7

The first search for radio messages from extra-terrestrial civilizations was called
A) Project Phoenix
B) Project Ozma
C) Project Serendip
D) Project META
E) Project ASTRO

Accepted Answer

The first search for radio messages from extra-terrestrial civilizations was called Project Ozma, named after the princess in L. Frank Baum's "Wizard of Oz" book series.

Question 8

What new technology has made it possible for astronomers to do "optical SETI" - searching for signals for extra-terrestrial civilization, not in the radio band of the spectrum, but in the visible-light band?
A) the Hubble Space Telescope was put into orbit
B) radio and TV signals have gone silent as much of the US adopts cable
C) astronomers have developed adaptive optics to deal with the twinkling of the stars
D) astronomers have built radio telescopes that can pick up the 3-degree microwave background
E) we have developed the ability to make laser pulses that are briefly brighter than the Sun

Accepted Answer

The technology referred to is the ability to make laser pulses that are briefly brighter than the Sun, which is achieved through advancements in laser technology. This technology is essential for searching for optical signals from extraterrestrial civilizations in the visible-light band of the spectrum.

Question 9

Which of the following spacecraft is NOT leaving the solar system?
A) Voyager 1
B) Voyager 2
C) Galileo
D) Pioneer 10
E) Pioneer 11

Accepted Answer

Galileo was intentionally crashed into Jupiter in 2003, while the other spacecraft continue to travel beyond the boundaries of the solar system.

Question 10

In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization?
A) yes, because such a star is probably old and a technological civilization will have had a long time to evolve and develop there
B) yes, because we have already found radio signals from another civilization living near a star in a globular cluster
C) no, because such a star would most likely not have a stable (main-sequence) stage that is long enough for a technological civilization to develop
D) no, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etc.) that we believe are necessary to start life as we know it
E) yes, because globular clusters are among the closest star clusters to us, so that they would be easy to search for radio signals

Accepted Answer

A star consisting entirely of hydrogen and helium would lack the heavier elements necessary for life as we know it to develop, making it an unlikely candidate for hosting a technological civilization.

Question 11

Photosynthesis, once it was planet-wide, changed the atmosphere of the Earth by introducing a significant amount of
A) oxygen
B) carbon dioxide
C) methane
D) ammonia
E) vibranium

Accepted Answer

Photosynthesis is responsible for introducing oxygen into the atmosphere, which drastically changed the planet's environment and allowed for the evolution of aerobic organisms.

Question 12

Which band of the electromagnetic spectrum do astronomers suggest is likely to be the best (cheap, little competition from nature, penetrates atmospheres) for communication between civilizations around different stars?
A) radio waves
B) x-rays
C) ultra-violet
D) infrared
E) gamma rays

Accepted Answer

Radio waves are the best choice for communication between civilizations around different stars as they are inexpensive, there is little competition from nature and they can penetrate through the atmosphere without much attenuation.

Question 13

We receive a radio message from a civilization around a star about 40 lightyears from Earth? If we reply right away, how long will it be between the time THEY sent the message and the time they receive our reply?
A) 40 years
B) 80 years
C) 400 years
D) 20 years
E) it depends on the speed of the radio wave; so it can't be calculated from the information given

Accepted Answer

Since the star is 40 lightyears away from Earth, it would take the radio signal 40 years to travel from the civilization to Earth. If we reply right away, it would take another 40 years for our radio signal to reach the civilization, resulting in a total travel time of 80 years.

Question 14

If alien beings found one of the Voyager spacecraft in a million years, what would they find aboard?
A) a container with a concentrated sample of the most common Earth bacteria
B) a flag from the Soviet Union
C) an audio and video record
D) a human skull done in bronze
E) a video tape with every episode of the original "Star Trek" TV series

Accepted Answer

The Voyager spacecraft contains a golden record with audio and visual recordings of Earth's culture and diversity, including greetings in different languages, music, and images of Earth's landscapes and inhabitants. This would provide the most comprehensive insight into humanity for any alien beings who discovered it. The other options are either unnecessary or not representative of humanity as a whole.

Question 15

The Drake Equation allows astronomers to estimate
A) the age of the universe
B) the location of the Sun within the Milky Way Galaxy
C) the number of civilizations out among the stars with which we might communicate
D) the rate at which the universe expands
E) the number of ducks that we in the United States use for food each year

Accepted Answer

The Drake Equation is used to estimate the number of civilizations in the Milky Way Galaxy with which we might communicate. It takes into account factors such as the number of stars that have planets, the number of planets that could support life, and the likelihood that intelligent life may evolve on those planets.

Question 16

What recent series of discoveries has made astronomers more optimistic about our prospects of finding life out there?
A) the discovery of a form of silicon-based life in the volcanic vents of Venus
B) the discovery of planets around thousands of stars in our Galaxy
C) the discovery of a black hole approaching our solar system at rapid speed
D) the discovery of many key building blocks of life in a crater near the polar region of the Moon
E) the discovery of a spaceship, built by an alien civilization, that crashed in New Mexico

Accepted Answer

The discovery of planets around thousands of stars in our Galaxy has made astronomers more optimistic about our prospects of finding life out there as it increases the number of potentially habitable worlds in the universe.

Quiz 30: Life in the Universe

Which of the following is a good summary of what most astronomers think about UFO reports in the popular media?

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is

Which of the following is a biomarker that could be used from an observatory around a nearby star, with the right equipment, to identify the Earth as a planet with life:

Which of the following questions is NOT part of what astronomers call the "cosmic haystack problem" in receiving messages from other civilizations in space?

Which of the following events in cosmic history is the most recent?

What makes the Earth different from the other worlds that might have life in the solar system (and easier to detect from far away) is that only Earth

The first search for radio messages from extra-terrestrial civilizations was called

What new technology has made it possible for astronomers to do "optical SETI" - searching for signals for extra-terrestrial civilization, not in the radio band of the spectrum, but in the visible-light band?

Which of the following spacecraft is NOT leaving the solar system?

In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization?

Photosynthesis, once it was planet-wide, changed the atmosphere of the Earth by introducing a significant amount of

Which band of the electromagnetic spectrum do astronomers suggest is likely to be the best (cheap, little competition from nature, penetrates atmospheres) for communication between civilizations around different stars?

We receive a radio message from a civilization around a star about 40 lightyears from Earth? If we reply right away, how long will it be between the time THEY sent the message and the time they receive our reply?

If alien beings found one of the Voyager spacecraft in a million years, what would they find aboard?

The Drake Equation allows astronomers to estimate

What recent series of discoveries has made astronomers more optimistic about our prospects of finding life out there?