ASTR 150 Week 15
Based on recent survey, scientists have estimated that what fraction of Sun-like stars have Earth-sized planets in their habitable zones?
22%
How many planets outside of our solar system have we discovered?
About 4000
Of all the potentially deadly phenomena in the Universe, which is most likely to kill YOU?
Asteroid impact
Drake Equation do we actually have observational knowledge rather than just a speculative estimate?
Both 𝑅∗ and 𝑓𝑝
By what method are most extrasolar planets discovered?
By observing a star's light dim slightly when the planet passes in front of the star
Why do we think extraterrestrial life would likely be carbon-based?
Carbon has real, significant advantages over alternatives like silicon.
What does the Fermi Paradox say?
Given all the time since the Big Bang and all the stars, why has some form of intelligent life in the Galaxy not established a network throughout the Galaxy and visited us?
Probably the most difficult factor to estimate in the Drake Equation is
L, the lifetime of a technologically advanced civilization
On the surface of which planet or moon in our planetary system have experiments been carried out to search for life-forms or evidence of life?
Mars
The first successful detection of interpretable signals from extraterrestrial civilizations was accomplished in which year?
Never—no such signals have been detected as yet.
How often do stars form in our galaxy, on average?
On average, 2-3 stars form per year.
Around which types of stars are we most likely to find planets supporting our kind of life forms?
Sun-like main-sequence stars
If an alien bacteria or virus lands on Earth it is unlikely to be seriously dangerous to humans why?
Terrestrial bacteria or viruses have evolved to become dangerous to humans.
What is the idea of panspermia for how life started on Earth?
That life was transported from space.
Based on recent surveys, how many stars have planets?
The vast majority of stars appear to harbor planets
What is the most likely explanation for Fermi's Paradox?
They Exist But Have Not Yet Communicated (e.g., they don't talk to lesser developed species)
If there are other civilizations at present in the Milky Way Galaxy, which statement is almost undoubtedly true?
They are far more technologically advanced than we are
Should we land on Mars and search for life?
Yes, if we found evidence of life it would have important scientific implications
Should we send robots to the icy moons to search for life?
Yes, if we found evidence of life it would have important scientific implications
The earliest evidence for life on Earth dates to
about 3.8 billion years ago
Terrestrial organisms have been found in water that is
hot,acidic,salty
What are the building blocks of life?
hydrogen, oxygen, nitrogen, carbon
The Drake equation attempts to predict
the number of technically advanced civilizations in our Galaxy
What defines the habitable zone around a star?
the region around a star where liquid water can exist on planetary surfaces
Scientists are now targeting Europa, one of Jupiter's moons, as a likely site for searching for elementary life-forms because
there is strong evidence for liquid water beneath the thick ice layer on its surface
