Unit 6

Question 1

Galaxy

Answer 1

a large group of stars

Question 2

Average galaxy size

Answer 2

100 billion stars, 100,000 light years in diameter

Question 3

galacitic disk

Answer 3

center of galaxy and flat disk

Question 4

globular cluster

Answer 4

stars orbiting the galactic center

Question 5

interstellar dust

Answer 5

obscures our view of the galaxy

Question 6

radio waves help us what

Answer 6

map out the galaxy

Question 7

How fast is the Sun revolving around the center of the Galaxy?

Answer 7

500,000 mi/hr

Question 8

What type of radiation can penetrate the dust clouds of our Galaxy, allowing us to see the spiral structure? (It is also known as 21 cm hydrogen radiation.)

Answer 8

radio

Question 9

cepheid variable star

Answer 9

gets brighter and dimmer in a regular pattern

Question 10

Henrietta Leavitt

Answer 10

figured out the pattern that relates to luminosity and cepheid variable stars, this allows us to find distance of stars

Question 11

Distant indicator and millions of light years

Answer 11

cepheid variables 15-20 ly, red supergiants 50 ly, blue supergiants 80 ly, Novae 80 ly, globular clusters 130 ly, supernovae 8,000 ly, brightest galaxy in cluster 15,000 ly

Question 12

What two properties of a Cepheid variable star do we need to know in order to calculate the approximate distance from Earth?

Answer 12

apparent magnitude
luminosity

Question 13

What two properties of a Cepheid variable star do we need to know in order to calculate the approximate distance from Earth?

Answer 13

apparent magnitude
luminosity

Question 14

types of galaxies

Answer 14

spiral, barred spiral, ellipticals, irregulars

Question 15

spiral

Answer 15

Sa, Sb, Sc, (a is tightly wrapped) SBa, SBb, SBc (B means barred)

Question 16

ellipticals

Answer 16

look like circles, E0-E7 (0 is more circular and 7 is more oval)

Question 17

irregulars

Answer 17

any other type of galaxy

Question 18

clusters

Answer 18

groups of galaxies

Question 19

dark matter

Answer 19

matter we are unable to observe from Earth

Question 20

quasars

Answer 20

100 times brighter than average galaxy, very far away

Question 21

Who developed a classification system for galaxies?

Answer 21

Edwin Hubble

Question 22

black hole

Answer 22

so strong gravity that light can’t escape

Question 23

escape velocity

Answer 23

how fast something must go to escape an objects gravity (shrink something and it has a higher escape velocity)

Question 24

event horizon

Answer 24

boundary of black hole

Question 25

active galaxies

Answer 25

brightness between normal galaxy and quasar

Question 26

galactic nuclei

Answer 26

bright starlike, called seyfert galaxies

Question 27

capricornus

Answer 27

the goat, shaped like a big upside down triangle, no bright stars

Question 28

libra

Answer 28

themis, shaped like a trapazoid, no bright star

Question 29

scorpius

Answer 29

the scorpion, shaped like a curved hook, bright star Antares

Question 30

sagittarius

Answer 30

the archer, shaped like someone with a bow, no bright star

Question 31

Observing a significant wobble in a star’s orbit would suggest what possibility (if no binary star is visible)?

Answer 31

Its companion star became a black hole.

Question 32

t/f Cepheid variables are useful for determining the distances to some galaxies.

Answer 32

true

Question 33

t/f Earth is near the center of the Milky Way Galaxy.

Answer 33

false

Question 34

Edwin Hubble's discovery of a Cepheid variable in the Andromeda nebula led him to conclude that the nebula was what?

Answer 34

a distant galaxy

Question 35

Who developed a classification system for galaxies?

Answer 35

Edwin Hubble

Question 36

Henrietta Leavitt found that the brighter appearing Cepheids always had longer periods of light variation. This is an expression of what?

Answer 36

period-luminosity relation

Question 37

If the Sun were to become a black hole, what would happen to Earth?

Answer 37

It would continue in the same orbit.

Question 38

How long does it take the Sun to revolve around the center of the galaxy?

Answer 38

two hundred million years

Question 39

Our sun is a member of which galaxy?

Answer 39

Milky Way

Question 40

Which type of radiation helped us map the galaxy?

Answer 40

21 cm radio waves

Question 41

What is the surface or boundary of a black hole called?

Answer 41

event horizon

Question 42

The Local Group contains

Answer 42

twenty-four galaxies

Question 43

t/f Quasars appear to be among the most distant objects known in the universe.

Answer 43

true

Question 44

What is believed to be at the center of most galaxies?

Answer 44

black holes

Question 45

t/f It would be impossible to orbit a black hole, because you would always be sucked in.

Answer 45

false