Stellar Astronomy 26,27,28,29

Why did Einstein introduce the cosmological constant into the equations of his General Theory of Relativity when describing the universe?

Einstein's equations required the universe to expand or contract

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?

At about 1 second after the beginning of the universe, one type of particle was able to start traveling freely through the universe. These particles are still with us, but they are extremely hard to detect. They are called:

Neutrinos

Think for a moment about an atom of the element lead (atomic number 82) inside the radio that you listen to in the morning. In which of the following places has this atom probably NOT been during the course of its existence?

The Sun

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

Type la supernovae

The first astronomer to show that spiral nebulae (today called spiral galaxies) have large Doppler shifts was

Vesto slipher

The rich galaxy cluster that is closest to our Local Group of galaxies is the

Virgo Cluster

About two thirds of the nearby spiral galaxies (which we can study in more detail) don't have a round central bulge, but instead show

a central bulge with a bar of stars in the middle

How do astronomers know that there aren't significant amounts of dark matter within our solar system?

a lot of dark matter would affect the motions of our spacecraft as the moce through the solar system

Which of the following is, to the best of our knowledge, in the habitable zone of its star:

a planet about 1.05 AU

A Congressman from Texas visits our National Observatory in Tucson, Arizona, and wants to be shown an object in the universe with the "biggest darn redshift you ever saw". What type of object should the astronomers show him?

a quasar

If you want to check on what conditions were like in the universe a few hundred thousand years after the Big Bang, what sort of instrument would it be best to use:

a satellite with infrared and microwave telescopes

Some astronomers searching for what the mysterious "dark matter" might be made of have pinned their hopes on MACHO's (MAssive Compact Halo Objects). What do they think these MACHO's are?

black holes, brown dwarfs, and white dwarfs in the regions outside the main disk of our galaxy

Galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally:

bluer and smaller

One of the most important observations in the history of astronomy was the one by Edwin Hubble that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this?

by observing a Cepheid variable in a nearby galaxy and using it to get the distance

According to our current understanding, giant elliptical galaxies form:

by the merger of a number of smaller galaxies in a cluster of galaxies

Which of the following statements about the different types (shapes) of galaxies is correct?

collisions and mergers between galaxies can sometimes change a galaxys type

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

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is

about 13.8 billion years

Roughly how many galaxies make up our Local Group?

about 60 or so

In the very distant future, given our best model of the accelerating universe, what will the universe look like?

all the stars will die

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

an audio and video record

By examining rich clusters of galaxies, such as the Coma Clusters, astronomers have discovered that spiral galaxies

are found mostly in the outer regions of such clusters

When astronomers have examined rich clusters of galaxies with their instruments, they have found that these clusters

are more likely to contain giant elliptical galaxies than poor clusters

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

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

Which of the following statements about dark matter is FALSE:

astronauts have a pretty good idea

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

The type of galaxy that consists almost entirely of old stars and is thus less blue (more yellow and reddish) than the other types is:

elliptical

Which type of galaxy is observed to contain mostly older stars?

elliptical

Where in space did the expansion of the universe begin?

everywhere at once

At first, right after the Big Bang, the universe was too hot for nuclei and electrons to combine into the kinds of neutral atoms that are familiar to us today. How soon after the beginning did it become cool enough for neutral atoms to form?

few hundred thousand years

One of the main projects being carried out by the Hubble Space Telescope is to measure the distances of galaxies located in groups dozens of millions of lightyears away. What method do astronomers use with the Hubble to find such distances?

finding cepheid variables and measuring their periods

What method would astronomers use to find the distance to a galaxy so far away that individual stars are impossible to make out (resolve)?

finding the redshift

What method would astronomers use to find the distance to a remote quasar?

finding the redshift and using Hubbles law

Which of the following is a biomarker that could be used from an observatory around a nearby star, with the right equipment, to identify the Earth as a planet with life:

free oxygen in the earths atmosphere

When quasars "shine" (in visible light and other kinds of radiation) with a lot of energy, where (what location) does this huge amount of energy come from?

from an accretion disk around a supermassive black hole

Astronomers believe that the large elliptical galaxies formed

from the collision and merger of many smaller fragments

Which is one reason that the typical galaxy's mass-to-light ratio (in units of the Sun's mass over the Sun's luminosity) generally greater than 1?

galaxies contain many more stars that shine much less brightly than the Sun

What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups and clusters of galaxies are organized?

galaxy groups are organized into huge filaments with great voids between them

Scientists looking at an overview of physics today understand that there are four forces that govern all action in the universe. These four forces are the strong nuclear force, the weak nuclear force, electro-magnetism and

gravity

What makes the Earth different from the other worlds that might have life in the solar system (and easier to detect from far away) is that only Earth

has a biosphere on its surface

To map out how clusters of galaxies are distributed in the universe, astronomers needed to know where each cluster was in the sky AND

how far away from us each cluster was

Which of the following is a way that having an active galactic nucleus (AGN), with a supermassive black hole in the center, can affect the development of a galaxy?

huge energetic jets from the accretion disk disturb and lessen star formation

Chemically, the process leading to life on Earth began with lots of liquid water and

hydrocarbons

If you wanted to find a type of atom in your little finger that has been in its present form (been the same element) since the beginning of the universe, which element should you look for?

hydrogen

In a distant galaxy, whose light is just arriving from 10 billion light years away, our spectroscope should reveal that the most common element is

hydrogen

Which of the following statements about the implications of Hubble's Law is FALSE?

if you were observing the universe from a distant galaxy

If we want to see what galaxies looked like at a time close to the beginning of the universe, where should we look?

in a direction away from the plane of the Milky Way

An astronomer who loved reading the Guinness Book of World Records when she was a child becomes obsessed with quasars and wants desperately to find the most distant quasar ever (the one with the largest redshift.) Where should she be looking to have the best chance of finding such a quasar?

in or near a distant cluster of galaxies

If a galaxy contains a great deal of "dark matter," what will that do the galaxy's mass-to-light ratio?

increase it quite a bit

How does a period of extremely fast inflation very early in the history of the universe explain the observation that the geometry of the universe looks flat (not curved) to us?

inflation increases the size of the universe

The cosmological principle in astronomy

is confirmed by many observations done by Hubble and many other astronomers since

According to the Cosmological Principle, the universe

is isotropic and homogeneous

Which of the following is not true about the Local Group of galaxies (of which the Milky Way is a member)?

it has about a thousand member galaxies

The Tully-Fisher method for measuring the distance to galaxies relies on the observed relationship between the luminosity of a spiral galaxy and

its rotational velocity

According to our modern "bottom-up" model of the formation of large structures in the universe, the structures that formed first were about the mass of a

large globular cluster or a small galaxy

Based on many surveys of the average density of matter in the universe (regular matter and dark matter), astronomers now conclude that the average density of the universe is

less than critical densitiy

Photosynthesis was a great step forward in the evolution of life on Earth, because with photosynthesis

life could extract chemical energy from sunlight

One reason that some scientists think that there may be life under the ice-crust of Jupiter's moon Europa is that:

life has been found on earth

If quasars are at the distances most astronomers believe they are, then (for the most luminous ones) their luminosities must be:

like the combined luminosity of a hundred trillion suns

There is some irony in the fact that the Hubble Space Telescope has shown that Edwin Hubble's classification scheme for galaxy shapes only works in the later stages of the universe. What have really deep pictures (going way back in time) taken with the Hubble Telescope shown about galaxies long ago (in the first few billion years after the Big Bang)?

long ago, galaxy shapes were not regular and organized

Which of the following does NOT happen when two galaxies collide?

many of the stars in one galaxy collide with the stars in the other

Today, astronomers find compelling evidence that the energy source of the quasars and active galaxies is

matter falling toward a supermassive black hole at the center of a galaxy

In describing the universe using his equations of general relativity, Einstein assumed that it was isotropic (the same in all directions.) What recent observations have confirmed that the universe is isotropic on the large scale?

measurement of the 3 degree cosmic background

If a galaxy contains a great deal of dark matter, then, compared to the mass-to-light ratio of the inner part, the mass-to-light ratio of the whole galaxy will be

more

Why is the use of Hubble's Law to measure distances to galaxies so important to astronomers?

most galaxies are so far away

According to Hubble's Law, if two galaxies are not part of our Local Group, and galaxy B is three times farther away from us as Galaxy A, then Galaxy B will

move away from us three times faster than A

Astronomers have discovered a planet orbiting Proxima Centauri, the star closest to the Sun. This is a star of spectral type M, with 12% the mass of the Sun and 15% the size of the Sun. The habitable zone around this star would be

much closer to the star than the suns

How can supermassive black holes at the centers of galaxies help new stars to form in that galaxy?

new stars form

Which of the following is not a way that astronomers can find how much dark matter there is in cluster of galaxies?

observe the radio waves coming from all dark matter

A graduate student in astronomy needs to measure the mass of a spiral galaxy she is studying for her PhD thesis. Which of the following observations would be important for her to make?

obtain the speed at which stars or gas near the outer regions of the galaxy are moving around

Photosynthesis releases a particular gas as a byproduct. This gas is:

oxygen

Photosynthesis, once it was planet-wide, changed the atmosphere of the Earth by introducing a significant amount of

oxygen

The satellite that has given us the most precise measurements of the characteristics of the cosmic background radiation is:

planck

How are galaxies and quasars related?

quasars are active supermassive black holes

Why do astronomers think that there are fewer quasars today than there were billions of years ago?

quasars are seen when the supermassive black hole at the center of a galaxy

How do astronomers now explain the fact that the energy emitting regions for quasars are so small?

quasars are the result of matter falling into a black hole

What makes astronomers believe that the energy source in quasars is only a few light months across (the distance light travels in a few months)?

quasars show variations in their energy output

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

Today we know that what all quasars have in common is that they appear to be small sources of energy with

redshifts that indicate they are far away

Which of the following observations is a convincing argument for the idea that quasars are located inside galaxies?

relatively nearby quasars show fuzz around them

When do astronomers now think that the "dark energy" began to accelerate the expansion of the universe?

several billion years after the Big Bang

Which of the following is a good summary of what most astronomers think about UFO reports in the popular media?

so far there is no sceintific evidence

Which of the following did NOT happen during the first few minutes after the Big Bang?

some very massive early stars formed

Compared to the mass of our own Milky Way Galaxy, the total mass we estimate for the Andromeda Galaxy is

somewhat bigger

Our Milky Way Galaxy is what type of galaxy?

spiral

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

spiral

The Tully-Fisher relation (looking at rotation speeds) only works for:

spiral galaxies

Why do galaxies collide, while stars almost never do?

stars are much further apart

What is the strongest known force in the universe?

strong nuclear force

The Sloan Digital Sky Survey

takes images and spectra of millions of objects, to find the positions and redshifts of as many galaxies and quasars as possible

When we determine the age of the universe using the Hubble Time, what important simplifying assumption goes into our calculations?

that the expansion of the universe has been happening at the same rate

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

The new instrument that made it possible for Edwin Hubble to demonstrate the existence of other galaxies in the early 1920's was:

the 100-inch reflector on Mount Wilson

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

the 3 degree cosmic microwave

If you wanted to write a complete "cosmic address" for yourself, including every location or structure you live in, which of the following would NOT be part of that address?

the Coma Cluster

The reciprocal of the Hubble constant (1/H) is a rough measure of the:

the age of the universe

How do astronomers currently think the amount of detectable (observable) matter in the universe compares to the amount of dark matter and dark energy?

the amount of detectable matter is far less than the amount of dark matter and energy

Scientists speculate that the properties (laws) of the universe must be the way they are because if they were significantly different, we would not be here to think about them. This idea is called

the anthropic principle

Which of the following statements about our modern ideas of how spiral galaxies form and develop is TRUE?

the central bulges of spiral galaxies

According to the most recent data from satellites making precise measurements of the properties of the cosmic background radiation (CBR),

the dark matter makes up just a little less than 70 percent

After the Big Bang, in order for the universe to become transparent to light and other electro-magnetic radiation, what had to happen?

the density of the universe had to decrease

The Hubble Space Telescope has enabled astronomers to explore an active galaxy such as M87 in remarkable detail. Which of the following observations of M87 is NOT an important part of the web of evidence that shows it must have a supermassive black hole at the center?

the discovery of a gravitational lens in M87

One place that astronomers think might have had life start long ago is Mars. Which of the following is not a discovery that we have made on Mars so far?

the discovery of organic materials

What recent series of discoveries has made astronomers more optimistic about our prospects of finding life out there?

the discovery of planets

What observation in astronomy, made AFTER the discovery of quasars, was a big help to astronomers in figuring out what quasars really were?

the discovery that the Milky Way Galaxy has a black hole

A friend of yours who is a science fiction fan hears you talk about the fact that astronomers now believe that the mechanism for the large energy output of quasars involves a supermassive black hole. He challenges you, saying something like "Oh come on, every science fiction fan knows that nothing, not even light, can escape from a black hole! How can a black hole be an energy source?" How would you respond to his objection?

the energy we see from quasars

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

Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the

the faster it is moving away from us

Which of the following events in cosmic history is the most recent?

the formation of life on earth

If a nearby galaxy still acts like a quasar today, what is the most likely explanation?

the galaxy must be undergoing a collision

An astronomer is observing a distant galaxy which looks blue. Which of the following can she conclude from this observation?

the galaxy must have a lot of star formation going on at the time we are seeing it

If a very distant galaxy looks blue overall to astronomers, from this they can conclude that:

the galaxy must have a lot of young stars

With enormous effort, a team of astronomers manages to collect enough light from a galaxy far, far away to produce a spectrum. That spectrum has lines from the elements carbon, silicon, and sulfur. This tells the team that

the galaxy must have had an entire generation of stars that was born, lived, and died

An astronomer discovers a massive galaxy which has four nuclei. What is a likely explanation for a galaxy having more than one nucleus?

the galaxy must have swallowed several smaller galaxies that were its neighbors

Which of the following is the Earth not located in?

the globular cluster M-13

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

The model of the universe that involves an enormous increase of scale during a very short time in the early universe is called:

the inflationary universe model

How do astronomers explain the energetic jets that come out of quasars and active galactic nuclei in opposite directions?

the jets are spit out

When astronomers make counts of how many quasars there are at different distances from us, what do they find?

the largest number of quasars can be seen at about the distance corresponding to a time

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 la supernovae

For galaxies that have super-massive black holes at their centers, how do astronomers find that the mass of the host galaxy and the mass of the black hole are related

the more massive the galaxy, the more massive the central black hole

Some scientists speculate that our universe is not the only universe that exists, but the only one we can gather evidence about. This idea is called

the multiverse theory

The Drake Equation allows astronomers to estimate

the number of civilizations out among the stars with which we might communicate

How do quasars demonstrate that the universe evolves with time?

the number of quasars reached a maximum some time ago

Which of the following is a recent (last few decades) discovery that confirms the key idea of the Copernican Principle?

the planets around other stars are common

According to our modern theories, the geometry of the entire universe (all of space-time) may be curved or warped. This is a pretty bizarre notion; what other discovery in astronomy has helped us believe that space may be able to curve or warp?

the properties of black holes

In which of the following domains of the universe have astronomers NOT found evidence for the presence of dark matter today?

the solar system

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

When astronomers say that the groups of galaxies are distributed isotropically, they mean that

the way galaxies are arranged in space looks the same in all directions

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

their shape

If quasars often resemble little blue stars, what was it about them that so surprised astronomers when they were discovered?

their spectral lines were at first hard to recognize

What discovery about Saturn's moon Enceladus has encouraged astronomers to think of that moon as a possible place where life might exist?

there are plumes of salty vapor

The reason type Ia supernovae are useful to astronomers for determining distances to other galaxies is that

these are very bright

Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers?

they are very close to us

Astronomers can now report that active star formation was going on at a time when the universe was only 20% as old as it is today. When astronomers make such a statement, how can they know what was happening inside galaxies way back then?

they examine the spectra of galaxies

The Andromeda Galaxy (our nearest spiral neighbor) has spectral lines that show a blue shift. From this we may conclude that:

this particular nearby galaxy is moving toward us

Astronomers have established that quasars and active galaxies have a lot of mass at their centers in a very small volume of space. Why can't this mass be in the form of a cluster of stars that are quite close to each other?

to fit as much matter into the cluster as we observe

One important way astronomers can learn in some detail about what happens when galaxies collide is

to stimulate galaxy collision on a large computer

Which of the following objects is considered useful to astronomers as a "standard bulb" for determining distances?

type la supernovae

A distant quasar shows a large redshift -- one so large, in fact, that the features we now see in the visible-light region of the spectrum would be invisible to us, were it not for the redshift. What band of the electro-magnetic spectrum were these features most likely in, before the spectrum was redshifted?

ultraviolet

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 jupiters moon

The "great voids" that astronomers studying galaxies are finding are:

very large regions of intergalactic space

After several decades of observation, astronomers have concluded that quasars are

very powerful and compact sources of energy

For the complex biochemical reactions of life (as we know it) to happen, a solvent is required. What is that solvent for life on Earth?

water

Which of the following questions is NOT part of what astronomers call the "cosmic haystack problem" in receiving messages from other civilizations in space?

we dont know how to receive signals in the wavelength range that is the most likely for interstellar communications

What new technology has made it possible for astronomers to do "optical SETI" - searching for signals for extra-terrestrial civilization, not in the radio band of the spectrum, but in the visible-light band?

we have developed the ability to make laser pulses that are briefly brigther than the sun

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

Which of the following is NOT a characteristic of a spiral galaxy?

when we take spectra of its stars

Which of the following can we NOT learn from studying the Doppler shifts in the spectrum of galaxies beyond our Local Group?

whether they have Jupiter-mass planets around many of their stars

From a scientific perspective, which of the following statements about life elsewhere in the universe is best supported by current evidence?

while we have evidence of the building blocks of life elsewhere in the universe

One of the things that our current "standard model" of the Big Bang Theory doesn't explain is

why the temperature of the cosmic microwave background is so uniform

Before you can use Hubble's Law to get the distance to a galaxy, what observation must you make of that galaxy?

you must take a spectrum of the galaxy and measure the red shift

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 textbook, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?

95 percent

Scientists think that the life we have on Earth today originated some time between 3.5 and 3.8 billion years ago. Yet the solar system and the Earth are known to be at least 4.5 billion years old. Which of the following is one reason life as we know it had to wait until 3.5 to 3.8 billion years ago to get going?

Before 3.8 billion years ago

The first satellite (spacecraft with instruments) to measure and confirm the cosmic microwave background was the:

COBE

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

The first scientist to propose a specific model (the primeval atom model) for the big bang was

Lemaitre

If we include the effects of deceleration in our calculations of the age of the universe, the age we get is:

Less than the hubble time

The astronomer who first solved the problem of the strange red-shifts seen in quasar spectra and thus helped us understand that the quasars must be distant objects was

Maarten Schmidt

The astronomer who assisted Edwin Hubble at the Mount Wilson Observatory and helped him establish the expansion of the universe was:

Milton Humason

The two scientists who first discovered the cosmic microwave background radiation were:

Penzias and Wilson

The first search for radio messages from extra-terrestrial civilizations was called

Project Ozma

Which of the following was not done by Edwin Hubble?

discovering the relationship between period and luminosity of a cepheid variable

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

dwarf elliptical