FiltersDone

Question type

Essay

Multiple Choice

Short Answer

True False

Matching

Exam 20: Astrobiology

Show Answer

Share

---

All types

Filters

Study FlashcardsPractice ExamLearn

Question 31

Multiple Choice

Review LaterAdd Note

Review Later

The so-called water hole, a region of the radio spectrum chosen for searches for signals from intelligent life because galactic and Earth-based noise and atmospheric absorption are at a minimum, is so named because

A) water vapor (H₂O) has an intense laserlike emission line at this wavelength that extraterrestrials might use to communicate with Earth.
B) two astronomically important wavelengths, the 21-cm line of H and a line from the hydroxyl radical OH, are in this region, the letters H and OH signifying water.
C) water vapor emissions from planets at this wavelength will be a good indicator of life on other planets because water is essential for life as known.
D) water vapor absorption in Earth's atmosphere reaches a sharp minimum at this wavelength.

Correct Answer

verified

Show Answer

Question 32

Multiple Choice

Review LaterAdd Note

Review Later

In a few decades, a new generation of powerful telescopes especially designed to find extrasolar planets may be operational and producing data. What might these results mean for the Drake equation?

A) With these results in hand, the Drake equation will become irrelevant.
B) The structure of the Drake equation itself will undoubtedly have to be drastically revised.
C) Astronomers will have much better values for the factors f_p (the fraction of stars that have planets) and n_e (the number of planets per solar system that are Earthlike) .
D) Astronomers will have much better values for the factors f_l (the fraction of Earthlike planets on which life actually arises) , f_i (the fraction of life-forms that evolve into intelligent species) , and f_c (the fraction of intelligent species that develop adequate technology and then choose to send messages out into space) .

Correct Answer

verified

Show Answer

Question 33

Multiple Choice

Review LaterAdd Note

What source of energy was used to trigger the manufacture of complex organic compounds in laboratory simulations of conditions in primordial planetary atmospheres?

Why is liquid water believed to be essential to the development of life on a planet or other body?

Earth has been sending out radio messages for about 120 years, so detection equipment on a hypothetical planet 120 light-years away might just now begin receiving them. What is the parallax angle subtended by a system at this distance? Can astronomers detect such a parallax angle with existing technology?

Which of these characteristics in extrasolar planets is one that astronomers look for as a likely characteristic of a life-bearing planet?

Which of these events of the past 150 years announced human presence on Earth MOST effectively to extraterrestrial watchers?

Modern laboratory experiments that repeated those of Urey and Miller in exploring the possibility of producing organic molecules (the building blocks of life) from mixtures of gases expected to exist in the early planetary system passed electrical discharges through which mixture of gases?

The earliest searches for radio signals from extraterrestrial civilizations were made about

MOST searches of space for evidence of intelligent life concentrate on radio wavelengths because

In 1974 a radio signal was sent from the Arecibo radio telescope toward the globular cluster M13, which is about 6.8 kpc distant. How long will it take this signal to reach M13?

In what way does the Drake equation combine the various factors (e.g., fraction of stars with planets, fraction of planets that can support life) in an attempt to determine the number of technically advanced civilizations existing elsewhere in the Milky Way Galaxy?

Other than Earth, which object in the solar system seems to be the only one capable of fostering an advanced civilization?

If astronomers are going to "listen" for electromagnetic radiation at 21 cm from extraterrestrial sources, then Earth had better not generate too many waves at this wavelength from terrestrial sources. The standard FM broadcast band (as observed on a radio dial) spans frequencies from 88 MHz (million cycles per second) to 108 MHz. How does the frequency of the 21-cm signal compare with the FM band? The frequency of the 21-cm line is

The classical laboratory experiments performed by Urey and Miller to explore the necessary conditions for the production of organic molecules (the building blocks of living things) in the solar system involved the passing of electrical discharges through what mixture of gases?

Why is it highly likely that life, should it exist elsewhere in the universe than just on Earth, would be based on carbon chemistry?

Which type of meteorite was found to contain large organic molecules that make up the building blocks of life and provide strong evidence for their extraterrestrial production?

In the Drake equation for estimating the possible number of technologically advanced civilizations in the Milky Way Galaxy, why does the factor for the rate at which solar-type stars form in a galaxy exclude massive stars with masses greater than about 1.5 times that of the Sun?

One of the first people to look for radio signals from extraterrestrial civilizations was

Does a planet's location within the Milky Way Galaxy affect the likelihood of evolving life on the planet?