Question

Can be multiple answers to each answer

16        According to the Drake estimate of the probability that intelligent life exists elsewhere in the Milky Way at the present time, the issues one must consider include:

a       the number of Population I stars in the galaxy.

b      the likelihood that stars are not members of close multiple star systems.

c       the main sequence lifetime of various types of stars.

d      whether stars are in a spiral arm at them moment.

e       the probability that carbon-based life will develop if the right conditions occur.

17        Among other considerations elliptical galaxies differ from spiral galaxies in that spirals:

a       have a much wider mass range.

b      have interstellar gas and dust.

c       are composed generally population II objects.

d      are all very old.

e       are much brighter on the average than  the brightest ellipticals.

18        Gravitational Lensing:

a       occurs when the gravitational field of a star is lens shaped.

b      is a valuable tool in determining the mass distribution of the intermediate object.

c       is a technique that can be used to magnify telescope images much more that is possible with optical imaging techniques.

d      has been clearly detected in some quasar images.

e       has helped to characterize the dark matter distributions around galaxies.

19        The Large Scale Structure of the Universe is best characterized as:

a       smooth and homogeneous on the scale of the distribution of superclusters of galaxies..

b      containing many large void regions.

c       having only rarely occurring galactic collisions (i.e. collisions of galaxies are relatively rare events).

d      not being affected very much by the so-called dark matter.

e       resembling a foam-like structure.

20.       Inflation during the Big Bang refers to:

a.     the rapid expansion that occurred when gravity separated from the other forces and briefly became repulsive.

b.     a process that can explain the current observation of the acceleration of the expansion.

c.     the general property of the Big Bang that refers to the expansion of the universe with time.

d.     the fact that at the earliest times before the inflation occurred we were in causal contact with a portion of the universe that extends far beyond the present known universe.

e.     the fact that the knowable universe is bigger than the known universe.

21.       The current evidence for the acceleration of the Universe Includes

a.     Éthe number and size of the giant black holes in the centers of galaxies.

b.     Éthe shift in the shape of the Hubble Law for times more recent than about 5 Billion Light-Years

c.     Éthe data from the ÒSupernova Project.Ó

d.     Éthe discovery of the existence of Dark Matter.

e.     Éthe observation that we seem to have less and less time to get things doneÉ.

22.       Dark Energy:

a.     Éhas been postulated to be responsible for the acceleration of the UniverseÕs expansion.

b.     Éis possibly due to quantum fluctuations of the vacuum.

c.     Éis any form of energy that is not light.

d.     Éis the same thing as dark matter according to EinsteinÕs Theory of Relativity.

e.     Écould provide the matter needed to make the Universe exactly flat.

23.       Life on Earth:

a.     Égenerally is all based on the DNA molecule.

b.     Éapparently started only about 500 Million years ago

c.     Ébegan with the emergence of Òextremophiles,Ó primitive bacteria-like cells that can exist in hostile environments.

d.     Éexisted as no more complex than single-celled bacteria for Billions of years

e.     Émay be a rare example in the galaxy in the sense that complex life is very rare.

24.       Black Holes:

a.     may exist at the cores of all large galaxies.

b.     may have been created in the Big Bang in all sizes, including ones that are much smaller than the SunÕs mass.

c.     will have very strong tidal forces as one approaches the event horizon, for all black holes regardless of mass.

d.     Can be see directly by observing the light they all emit from their event horizons.

e.     are believe to be the source of ALL jet phenomenon seen in astronomical objects including stars.

25.       The greatest threats to the continued existence of the human species include:

a.     Éour own rapid population growth.

b.     ÉGlobal Warming from the emission of green house gases.

c.     Énew diseases that might wipe out all human beings.

d.     Éthe threat of invasion by a more advanced civilization and species from the stars.

e.     Éthe threat of major natural disasters like super-volcanoes and asteroid or comet impacts.

Answer 1

16. Drake equation depends upon the rate of star formation, the probability of these stars having planets and suitable life forms in these planets. Thus the drake estimate must include

e. the probability that carbon-based life will develop if the right conditions occur.

Earlier it was estimated that the stars can have planets in it only if it is a single star system. This removed almost half the star population from including. But later it was discovered that there are few planets present in multiple closed star system also.

17. spiral galaxy have

b      have interstellar gas and dust.

e       are much brighter on the average than the brightest ellipticals.

they have population I stars. Elliptical galaxies have stars which are old and there is minimal star formation.

18.

Gravitational Lensing happens when the light ray coming from a distant object bends or is distorted. Thus,

b      is a valuable tool in determining the mass distribution of the intermediate object.

d      has been clearly detected in some quasar images.

e       has helped to characterize the dark matter distributions around galaxies.

19.

The Large Scale Structure of the Universe is best characterized as:

a       smooth and homogeneous on the scale of the distribution of superclusters of galaxies. (while on a smaller scale they are inhomogeneous.)

b      containing many large void regions.

e       resembling a foam-like structure.