AST Final
Given that life on Earth appears to have arisen quite easily and rapidly suggests that the factor fl, in the Drake equation could be close to
1
Suppose there are a million habitable planets in our galaxy, that one in ten are habitable, that one in a thousand planets with life had at some point had an intelligent civilization, and that one in a hundred civilizations that has ever existed is in existence now. Given this, how many civilizations are in existence now?
1
Approximately how soon might we expect an immediate response from a civilization that received the signal we sent to the globular cluster M13 (21,000 light-years away) in 1974?
42,000
What is the "Wow!" signal?
It is a strong radio signal of unknown origin that did not repeat
Our best hope for determining that life on an extrasolar world lies in
Obtaining spectra that allow us to determine atmospheric composition
Which of the following signals from an advanced civilization would be easiest to detect?
high intensity, narrow bandwidth
The factor L, in the Drake equation depends on
how long civilizations survive once they have arisen
The Luyten 726-8 binary system is approximately 9 light-years away. If we send a spacecraft to visit this system traveling at 90% of the speed of light, how long will a one-way trip take as measured from the Earth?
10 years
Why do most astronomers think that the search for biosignatures and not SETI will more likely lead to the first detection of probably extraterrestrial life?
Because even life on Earth was microbial for most of its time
the complete version of the Drake equation allows us to estimate the number of
Because even life on Earth was microbial for most of its time
Which of the following factors in the simplified Drake equation is least well known?
L fraction of civilization-bearing planets that have intelligent civilizations on them now
Which of the following factors in the simplified Drake equation is best known?
Ne the number of habitable planets in our galaxy
What is/are examples for possible biosignatures?
The seasonal variation in Mars's atmospheric methane abundance The large abundance of free oxygen in Earth's atmosphere The characteristic change in surface reflectivity due to the presence of vegetation The seasonal variation in Earth's atmospheric CO2 abundance
How is the "Fermi Paradox" normally stated?
Where is everybody?
Which of the following questions best represents the Fermi paradox?
Why haven't we found any evidence of a galactic civilization?
What is the distinguishing characteristic of a signal that SETI scientists performing radio searches look for?
a signal that extends over only a narrow band of frequencies
Which of the following cases in the Drake equation would be the minimum necessary condition for us to be the only intelligent civilization currently in our galaxy?
any one of the factors to be zero
Traveling at their current speeds, how long would it take the Pioneer and Voyagerprobes to travel the distance to the nearest stars?
at least 100,000
The range of frequencies that are contained in a particular radio signal is referred to as its
bandwidth
Given how many times intelligent civilizations could have appeared over the universe's history, it is most likely that if other civilizations exist, they will
be much more advanced than us
Which is the most common type of spacecraft propulsion used today?
chemical rockets
The ratio of an animal's brain weight to body weight is thought to be roughly proportional to its
intelligence
The complete version of the Drake equation allows us to estimate the number of
intelligent civilizations capable of communicating in our galaxy now
On the basis of the scientific method, which of the following would be considered conclusive evidence that we are being visited by aliens?
none of these would be conclusive
In the coming decades astronomers will explore the atmospheres of nearby habitable exoplanets using spectroscopic observations. Which one of the following results would be regarded as the most compelling biosignature?
the detection of molecular oxygen (O2), ozone (O3) and water (H2O)
If we would hav really good values for each of the terms in the Drake Equation, what would we get as a result?
we would have a realistic estimate for the number of communicative, technological civilizations in the Milky Way
