final

Question 0

which scientist discovered that the equations he had derived predicted an expanding universe, then modified his equations to eliminate this expansion?

Answer 0

Albert Einstein

Question 1

what do cosmologists study

Answer 1

origin, structure and evolution of the universe

Question 2

why is the universe expanding

Answer 2

spacetime itself is expanding, carrying the galaxies (superclusters of galaxies) with it.

Question 3

which on of the following statements is a correct description of the expansion of the universe

Answer 3

spacetime is something real, with galaxies inside it; as spacetime expands, the galaxies( or superclusters of galaxies) are carried along by the expansion

Question 4

what is the cosmological redshift

Answer 4

stretching of the wavelengths of photons as they travel through expanding space

Question 5

the cosmological redshift of the light from very distant galaxies is caused by the

Answer 5

expansion of space, stretching the photon’s wavelength while the photon is traveling toward earth

Question 6

what is it that keeps localized regions of space, such as things on earth, planetary systems, star clusters, and whole galaxies, from participating in the general expansion of the universe?

Answer 6

mutual gravitational attraction between objects in these systems

Question 7

what is the cosmic microwave background radiation?

Answer 7

radiation left over from the Big Bang after the universe expanded and cooled

Question 8

the cosmic background radiation is

Answer 8

low intensity radio noise, with a 3K blackbody temperature, almost uniform in intensity in all directions.

Question 9

the cosmic background radiation is the

Answer 9

electromagnetic remnants of the explosion in which the universe was born.

Question 10

good evidence for an original Big Bang that “created” our universe comes from

Answer 10

a background “glow” of microwaves, with blackbody temperature of about 3k

Question 11

in relation to the universe, what does isotropy mean

Answer 11

the universe looks the same in all directions

Question 12

what do we mean when we say that the universe is homogeneous

Answer 12

at any given time, the universe looks the same at all locations

Question 13

how many fundamental forces are there in nature at the present time under normal conditons

Answer 13

four: strong, weak, electromagnetic and gravitational

Question 14

what is the range of the electromagnetic force (the maximum distance over which it acts?

Answer 14

infinity

Question 15

which is the four fundamental forces holds the electrons in the atom/

Answer 15

electromagnetic force

Question 16

what is the gravitational force ( the maximum distance over which it acts)

Answer 16

infinity

Question 17

what makes gravity the main force determining the large scale structure of the universe

Answer 17

while the electromagnetic force of a charged particle has an infinite range, it is usually screened and limited by the existence of charges of the opposite sign. Ordinary matter has only one sign and therefore does not screen other gravitational forces.

Question 18

what are quarks

Answer 18

component particles making up protons and neutrons

Question 19

what are the particles that make up protons and neutrons

Answer 19

quarks

Question 20

most quasar produce their strongest emissions in which region of the electromagnetic spectrum

Answer 20

infrared

Question 21

what is the most outstanding feature of a quasar compared with other objects in deep space

Answer 21

prodigious output of energy

Question 22

quasars in our universe are

Answer 22

relatively common. Over 10000 have been identified so far

Question 23

quasars all appear to be

Answer 23

moving away from us at very high speeds, up to about 90 of the speed of light

Question 24

the specific characteristics that identify most quasars are

Answer 24

bright, starlike appearance with very high redshifts and hence very large distances indicating very energetic sources.

Question 25

an intense radio source is found to coincide with a starlike object whose spectrum contains a pattern of intense emission lines in in the visible range that matches that of the Lyman uv hydrogen spectral lines but is very redshifted. what is this object

Answer 25

quasars

Question 26

the extreme redshifts of quasar spectra are caused by

Answer 26

very high recession speeds of the sources away from the Milky Way galaxy

Question 27

compared with the total output of energy from the Milky Way galaxy, what is the equivalent output of a typical quasar?

Answer 27

100 times brighter

Question 28

seyfert galaxies are

Answer 28

active galaxies with bright starlike nuclei

Question 29

seyfert galaxies are a distinct class of galaxies because they

Answer 29

have very bright, very hot starlike central cores with variable energy output

Question 30

which of one of the following properties do seyfert galaxies and the Milky Way galaxy share

Answer 30

spiral galaxy classification

Question 31

sayfert galaxies are

Answer 31

spiral galaxies with extremely active cores

Question 32

which of the following objects is not classified as an active galaxy?

Answer 32

barred spiral

Question 33

the central engine of an active galaxy appears to be

Answer 33

a supermassive black hole at the center of an accretion disk and material being projected out perpendicular to the disk in both directions.

Question 34

for gravitational lensing of a distant quasar to occur, the galaxy producing the lensing must

Answer 34

be almost perfectly placed on a line between Earth and the quasar.

Question 35

the mechanism that appears to generate two extensive regions of rado emission near active galaxies is

Answer 35

the double image of a single source behind the galaxy produced by gravitational lensing by the galaxy

Question 36

in observation of a double quasar image produced by gravitational lensing, fluctuations on the intensity of one image appear to be delayed compared with equivalent variations on the other image.

Answer 36

the optical path through the gravitational lens producing one images is longer than that for the other image.

Question 37

what is an Einstein ring

Answer 37

example of the image formed by a gravitational lens.

Question 38

who developed the classification system that divides galaxies into spiral, elliptical, and irregular and classifies spirals by the size of their nuclear region and the tightness of winding of their arms

Answer 38

edwin hubble

Question 39

what is the basic shape of a spiral galaxy

Answer 39

round, flat disk with long lanes of stars that curve outward from a round nuclear region of uniform brightness

Question 40

which of the following terms does not name one of the four main categories of galaxies in the Hubble classification scheme

Answer 40

starbursts

Question 41

what is the hubble classification for a spiral galaxy with a large nuclear region and tightly wound arms

Answer 41

sa

Question 42

what is the hubble classification for a spiral galaxy with a oderately sized nuclear region and moderately wound arms

Answer 42

sb

Question 43

what is the hubble classification for a spiral galaxy with a small nuclear region and loosely wound arms

Answer 43

sc

Question 44

according to the hubble classification scheme, an sc galaxy has a

Answer 44

small central bulge and loosely wound spiral arms

Question 45

a typical spiral galaxy has ----- stars in a disk of diameter---ly

Answer 45

10 -11, 10-5

Question 46

spiral galaxies are classified in terms of increasing tightness of their spiral arms as types Sa, Sb, Sc. However many spiral galaxies are aligned edge on to earth and their spiral arms cannot be seen. which other parameter that is directly related to spiral arm tightness can be easily seen edge-on and can therefore be used to provide this classification.

Answer 46

size of the nuclear bulge

Question 47

a particular galaxy appears round , with a nuclear region of uniform brightness and an outer region that is broken up into curved but fuzzy and poorly defined lanes of stars and light gas clouds. How would this galaxy be classified

Answer 47

flocculent spiral

Question 48

a particular galaxy appears round with a nuclear region of uniform brightness and an outer region that is broken up into long curved well defined lanes of stars and light gas clouds. How would this galaxy be classified

Answer 48

grand design spirals

Question 49

one difficulty with the density wave theory is that

Answer 49

we are unsure of the mechanism that produces the energy output necessary to sustain the density wave.

Question 50

according to the theory of self propagating star formation, the spiral arms of flocculent spiral galaxies are broad and poorly designed because

Answer 50

the spiral arm segments are defined only by the relatively short-O and B type stars.

Question 51

why do the spiral arms show up so clearly in spiral galaxies

Answer 51

stars are spread almost uniformly over the galaxy( outside the nuclear bulge) but the brightest stars occur only in the spiral arms, where their brightness and the fact that they illuminate gas clouds make the arms stand out.

Question 52

why is the Milky Way Galaxy different from most spiral galaxies

Answer 52

The Milky Way has at least four spiral arms, whereas most galaxies have only two.

Question 53

how does the amount of dust and gas in a spiral galaxy vary with the classification of the galaxy

Answer 53

the most loosely wound galaxy, Sc, has the most dust and gas in its arms.

Question 54

what is an SBc galaxy

Answer 54

galaxy with a small nuclear bulge and loosely wound arms starting from the ends of a straight bar through the nuclear bulge.

Question 55

what is an elliptical galaxy

Answer 55

galaxy with an elliptical outline and a smooth distribution of brightness but no apparent structure.

Question 56

elliptical galaxies look far less impressive than spiral galaxies because

Answer 56

they contain no gas and dust clouds or young hot stars

Question 57

what name is give to a galaxy with a smooth distribution of brightness and a round shape

Answer 57

E0

Question 58

which of the following statement is not a characteristic of elliptical galaxies

Answer 58

elliptical galaxies have a disk and a central bulge but no spiral arms

Question 59

an elliptical galaxy typically contains which of the following primarily old kind of stars.

Answer 59

primarily old metal poor stars

Question 60

an astronomer studying a galaxy finds that its spectrum shows only old, low mass, population II stars and photographs of the galaxy show little or no interstellar gas or dust. what kind of galaxy i this astronoer studying

Answer 60

elliptical galaxy

Question 61

how are the magellanic clouds the two nearby satellite galaxies of thee milky way galaxy classified

Answer 61

irregular galaxies

Question 62

the megellanic clouds as seen from the southern hemisphere are examples of what type of objects.

Answer 62

irregular galaxies

Question 63

in which of the following types of galaxies is star formation no longer occuring.

Answer 63

elliptical galaxies

Question 64

recent evidence suggests that galaxies formed

Answer 64

from the mergers of hundreds of smaller objects

Question 65

when swirling eddies of gas rich matter in the universe collide and form a disk centered on an especially massive black hole and lot of dark matter we believe the following type of galaxy will form

Answer 65

normal spiral

Question 66

overall through space galaxies are

Answer 66

concentrated on the surface of huge open spaces or voids like soap bubbles

Question 67

how are galaxies spread throughout the universe

Answer 67

clusters of galaxies exist that are themselves often clustered into superclusters. Clusters and superclusters appear t be distributed on surfaces surrounding empty regions of space.

Question 68

The Milky Way galaxy is a

Answer 68

member of a small cluster of galaxies

Question 69

what is the local group

Answer 69

clusters of about 40 galaxies of which the Milky Way is one

Question 70

what is a rich cluster of galaxies

Answer 70

cluster containing thousands of galaxies

Question 71

what i a poor cluster of galaxies

Answer 71

a cluster containing a few dozen galaxies

Question 72

collision between galaxies

Answer 72

can las hundreds o millions of years

Question 73

what is a starburst galaxy

Answer 73

galaxy with an unusually large number of new born stars

Question 74

globular clusters

Answer 74

can be formed in collision of galaxies and thus can be young if the collision occurred recently

Question 75

as much as 90% of the matter in the universe may be unseen dark matter " Where is this dark matter

Answer 75

Dark matter appears to be concentrated in spherical haloes around galaxies but extends several times the radius of visible matter

Question 76

dark matteer in clusters of galaxies

Answer 76

is distributed mostly in and around the galaxies in a cluster, not in the voids between galaxies