Astro Final

imagine we receive a radio message from a civilization around a star about 40 lightyears from Earth. If we reply right away, how long will it be between the time THEY sent the message and the time they receive our reply?

80 years

According to our current understanding, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?

95%

How does a lenticular galaxy differ from a normal spiral galaxy?

It has no spiral arms.

What galaxy did Edwin Hubble study to demonstrate the Milky Way was not the only galaxy in the universe?

M31

The standard bulbs (standard candles) that made it possible for astronomers to discover the acceleration in the expansion of the universe were

Type Ia supernovae

Astronomers today know a lot about the size and shape of the Milky Way Galaxy. Which of the following common objects most resembles the shape of our Galaxy?

a CD or DVD

Which of the following types of protogalactic clouds is most likely to form an elliptical galaxy?

a dense cloud with very little angular momentum

You suddenly get an uncontrollable urge to find out more about the other side of the Milky Way Galaxy (the regions beyond the center). Where should you rush off to?

a radio telescope that can observe at 21-cm wavelengths

What evidence supports the idea that a collision between two spiral galaxies might lead to the creation of a single elliptical galaxy?

all of the above

If alien beings found one of the Voyager spacecraft in a million years, what would they find aboard?

an audio and video record

Compared with stars in the disk, orbits of stars in the halo

are elliptical, with random orientation.

According to the models of the universe we discussed in this course, why do the galaxies move apart (why do we have Hubble's law)?

as a result of the Big Bang, space itself is stretching, and this stretching carries the galaxies away from each other

In our modern view of the expansion of the universe, we understand that it is space that is stretching; individual galaxies don't speed away from each other as if they were rockets. In that case, why do galaxies show a red-shift?

as space stretches, the waves of radiation in space also stretch and their wavelength increases

Which of the following statements about dark matter is FALSE:

astronomers have a pretty good idea what the dark matter is made of

Which of the following statements about the early universe (as envisioned by the standard model of cosmology) is FALSE?

at the very beginning, the energies were so great that the universe was actually contracting for a while

How can we see through the interstellar medium to know more about the center of the Galaxy?

by observing in high-energy wavelengths such as X rays and long wavelengths of light such as radio waves

Today, we believe that only a small number of elements were actually formed during the Big Bang. Which of the following was NOT one of these:

carbon

Scientists are impressed with extremophiles, life forms that can survive under what seems to humans to be extremely unpleasant conditions. In which of the following environments have we not found life:

conditions resembling the photosphere of the Sun

Which type of galaxy is very difficult to see, but (astronomers recently realized) may be very common?

dwarf elliptical

Which of the following types of galaxies are most commonly found in large clusters?

ellipticals

Which of the following types of galaxies are most spherical in shape?

ellipticals

What kinds of objects lie in the halo of our galaxy?

globular clusters

Where does most star formation occur in the Milky Way today?

in the spiral arms

Radio astronomy has played a pivotal role in showing us the detailed structure of the Milky Way Galaxy. Which of the following techniques has allowed astronomers to know more about the supermassive black hole in the Milky Way?

interferometry

In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting ENTIRELY of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization?

no, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etc.) that we believe are necessary to start life as we know it

Compared with our Sun, most stars in the halo are

old, red, and dim and have fewer heavy elements.

Which band of the electromagnetic spectrum do astronomers suggest is likely to be the best (cheap, little competition from nature, penetrates atmospheres) for communication between civilizations around different stars?

radio waves

Compared to spiral galaxies, elliptical galaxies are

redder and rounder.

Our Milky Way Galaxy is what type of galaxy?

spiral

The disk component of a spiral galaxy includes which of the following parts?

spiral arms

The type of galaxy that sometimes has a distinct bar of stars running across the central region is

spiral galaxy

In the early 1950's, Stanley Miller and Harold Urey conducted a series of pioneering laboratory experiments involving simulations of the early Earth. What did these experiments reveal?

that under the conditions on the early Earth, they could synthesize some of the building blocks of life in a laboratory

Which of the following is pretty good evidence that the universe began with a Big Bang?

the 2.7-degree cosmic microwave background radiation

Which of the following statements about the nuclear bulge of our Galaxy is FALSE?

the best way to learn more about it is to observe in ultraviolet

Astronomers have measured that there is more helium in the universe than can be explained by the fusion in stars over the last 13 billion years. How do they think the extra helium got into the universe?

the extra helium was made during the first few minutes of the Big Bang, when the entire universe was hot enough for fusion to occur briefly

When they talk about the Copernican principle, philosophers and astronomers mean that:

the idea that there is nothing special about our place in the universe

Recent observations indicate that the universe is expanding faster today than it was a few billion years ago (that, in other words, the expansion of the universe is accelerating.) What kind of observations have led astronomers to this surprising conclusion?

the measurement of galaxy distances using Type Ia supernovae

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is

the speed of light

Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies?

their shape

According to astronomers, which of the following places in the outer parts of our solar system might be a reasonable place for life to exist?

under the ice of Jupiter's moon Europa

In which of the following places have astronomers NOT found evidence for the building blocks of life (organic compounds)?

we have found evidence for such materials in all of the above sites