1 Does a planet\'s location within the Milky Way Galaxy affect the likelihood of
ID: 292806 • Letter: 1
Question
1
Does a planet's location within the Milky Way Galaxy affect the likelihood of evolving life on the planet?
No. As long as a star is nearby the chances for the evolution of life would not seem to depend on the rest of the galaxy.
b. Yes. The closer to the center of the galaxy a planet is, the greater will be the density of stars. Being bathed in large amounts of light should increase the possibilities of the evolution of life.
c. Yes. A planet on the outer edge of the galaxy would be susceptible to radiation from outside the galaxy because it would not be protected by the galactic magnetosphere. Chances for life would not be good.
d. Yes. Stellar systems too far from the galactic center are deficient in metals. Such elements are necessary to build Earthlike planets and life as we know it.
2
At the present time, the search for extraterrestrial life in the solar system has been concentrated on a few bodies. These do not include
a. Venus.
b. Mars.
c. Europa.
d. Callisto.
3.
One of the “quiet” bands in the electromagnetic spectrum used for SETI is the so-called “water hole” between about 103 and 104 MHz. What is the principal source of the natural signals in this frequency band?
emissions from the water molecule
b. emissions from oxygen molecules
cosmic microwave background radiation
d. radio emission from terrestrial sources
4.
One of the important numbers in determining how many extraterrestrial civilizations there may be at the present time in the Milky Way Galaxy is the following: Out of the stars that have planets, what fraction, fs, has planets suitable for life? (This number is similar to the number ne in the Drake equation.) Based on the extrasolar planets already found by astronomers (see Sections 5-11 and 5-12 of Discovering the Universe, 10th ed.), what is a good guess for fs? (Note: If all stars with planets have at least one planet suitable for life, then fs = 1; if no such star anywhere in the Milky Way has a planet suitable for life, then fs = 0.)
fs = 0 since no star has yet been found to have an inhabitable planet
b. close to fs = 1 since most stars so far found to have planets have high-mass planets (similar to Jupiter or larger) orbiting far from the star, indicating that the solar system is probably typical of planetary systems in general
c. close to fs = 1/2 since about half the stars so far found to have planets have planets similar in mass to Earth orbiting the star at about Earth's distance from the Sun
d. fs less than about 1/10 since most stars so far found to have planets have high-mass planets (similar to Jupiter or larger) orbiting close to the star, which would disrupt the orbit of an inhabitable planet
5. In the 1970s the belief was widely held that life could exist only where it had access to the light from a star. What is the current status of this belief?
a. Since the advent of astrobiology, a great deal of research has gone into this concept. But we still see sunlight and its effect through photosynthesis on green plants as the basis of life, so the belief still stands.
b. The discovery of hyperthermophiles and similar phenomena has done away with this belief.
c. This belief was discarded with the discovery of silicon-based life which does not rely upon sunlight.
d. The discovery of ancient life forms buried under the crust of meteorites has caused this belief to be discarded.
6.
What is the status of the search for extraterrestrial intelligence?
The search must rely upon only small, inexpensive TV satellite antennas, and thus most astronomers believe it cannot succeed.
b. We have received on several occasions repeated signals which appear to be from some intelligent source, but we are waiting to receive one from the vicinity of an Earthlike planet before declaring that SETI has made contact with an extraterrestrial race.
c. Because of funding limitations the entire program has been terminated and is no longer active.
d. We have occasionally detected particularly strong or unusual signals from space, but they have not been repeated so we do not believe they are from an intelligent source.
a.No. As long as a star is nearby the chances for the evolution of life would not seem to depend on the rest of the galaxy.
b. Yes. The closer to the center of the galaxy a planet is, the greater will be the density of stars. Being bathed in large amounts of light should increase the possibilities of the evolution of life.
c. Yes. A planet on the outer edge of the galaxy would be susceptible to radiation from outside the galaxy because it would not be protected by the galactic magnetosphere. Chances for life would not be good.
d. Yes. Stellar systems too far from the galactic center are deficient in metals. Such elements are necessary to build Earthlike planets and life as we know it.
2
At the present time, the search for extraterrestrial life in the solar system has been concentrated on a few bodies. These do not include
a. Venus.
b. Mars.
c. Europa.
d. Callisto.
3.
One of the “quiet” bands in the electromagnetic spectrum used for SETI is the so-called “water hole” between about 103 and 104 MHz. What is the principal source of the natural signals in this frequency band?
a.emissions from the water molecule
b. emissions from oxygen molecules
c.cosmic microwave background radiation
d. radio emission from terrestrial sources
4.
One of the important numbers in determining how many extraterrestrial civilizations there may be at the present time in the Milky Way Galaxy is the following: Out of the stars that have planets, what fraction, fs, has planets suitable for life? (This number is similar to the number ne in the Drake equation.) Based on the extrasolar planets already found by astronomers (see Sections 5-11 and 5-12 of Discovering the Universe, 10th ed.), what is a good guess for fs? (Note: If all stars with planets have at least one planet suitable for life, then fs = 1; if no such star anywhere in the Milky Way has a planet suitable for life, then fs = 0.)
a.fs = 0 since no star has yet been found to have an inhabitable planet
b. close to fs = 1 since most stars so far found to have planets have high-mass planets (similar to Jupiter or larger) orbiting far from the star, indicating that the solar system is probably typical of planetary systems in general
c. close to fs = 1/2 since about half the stars so far found to have planets have planets similar in mass to Earth orbiting the star at about Earth's distance from the Sun
d. fs less than about 1/10 since most stars so far found to have planets have high-mass planets (similar to Jupiter or larger) orbiting close to the star, which would disrupt the orbit of an inhabitable planet
5. In the 1970s the belief was widely held that life could exist only where it had access to the light from a star. What is the current status of this belief?
a. Since the advent of astrobiology, a great deal of research has gone into this concept. But we still see sunlight and its effect through photosynthesis on green plants as the basis of life, so the belief still stands.
b. The discovery of hyperthermophiles and similar phenomena has done away with this belief.
c. This belief was discarded with the discovery of silicon-based life which does not rely upon sunlight.
d. The discovery of ancient life forms buried under the crust of meteorites has caused this belief to be discarded.
6.
What is the status of the search for extraterrestrial intelligence?
a.The search must rely upon only small, inexpensive TV satellite antennas, and thus most astronomers believe it cannot succeed.
b. We have received on several occasions repeated signals which appear to be from some intelligent source, but we are waiting to receive one from the vicinity of an Earthlike planet before declaring that SETI has made contact with an extraterrestrial race.
c. Because of funding limitations the entire program has been terminated and is no longer active.
d. We have occasionally detected particularly strong or unusual signals from space, but they have not been repeated so we do not believe they are from an intelligent source.
Explanation / Answer
1.d. Yes The stellar systems too far from the galactic center are deficient in metals. Such elements are necessary to build Earthlike planets and life as we know
2. d. Castillo. Callisto is a large moon orbiting Jupiter. It has an ancient, cratered surface, indicating that geological processes could be dead.
3. emissions from the water molecule. The presence of molecules in the intersteller absorbs radio noise at these frequencies.
4. fs less than about 1/10 since most stars so far found to have planets have high-mass planets (similar to Jupiter or larger) orbiting close to the star, which would disrupt the orbit of an inhabitable planet.
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