Astronomy Final Exam

Question 1

Galactos is the Greek word for _____

Answer 1

milk

Question 2

What makes up the milky way?

Answer 2

stars, dust, and gas

Question 3

The middle of a galaxy is called a _____

Answer 3

bulge

Question 4

The Milkyway is how “tall”?

Answer 4

1000 light years`

Question 5

How wide is the Milkyway?

Answer 5

100,000 light years

Question 6

3 main categories of galaxies

Answer 6

elliptical, spiral, irregular

Question 7

Spiral galaxies are normally what color?

Answer 7

blue

Question 8

Giant ellipticals are often found in _____ consisting of hundreds or thousands of galaxies.

Answer 8

rich clusters

Question 9

The Milkyway and Andromeda are each a collection of _____ and _____

Answer 9

small dwarf spheroidal and irregular glaxies

Question 10

Nearest cluster to ours

Answer 10

Virgo

Question 11

Distance to Virgo

Answer 11

52 Mly

Question 12

The 4 brightest galaxies are ______ galaxies

Answer 12

giant elliptical

Question 13

The nearest “rich” cluster is _____

Answer 13

Coma, as many as 10,000 galaxies

Question 14

Measuring galaxy distance

Step 1: __________

Answer 14

determine size of the solar system using radar

Question 15

Measuring galaxy distance

Step 2: _________

Answer 15

determine the distances of stars out to a few hundred light years using parallax

Question 16

Measuring galaxy distance

Step 3: ________

Answer 16

main sequence fitting of star clusters

Question 17

Measuring galaxy distance

Step 4: _________

Answer 17

Because the period of cepheid variable stars tell us their lumosities, we can use them as standard candles

Question 18

Inverse square law

Answer 18

M = L / 4(3.14)d^2

Question 19

Cepheid variables and Type 1a supernovae can be used as _______

Answer 19

standard candles

Question 20

Hubbles Law

Answer 20

v = Ho d
v = velocity
Ho = hubbles constant
d = distance

Question 21

More distant galaxies are moving at a much _____ rate

Answer 21

faster

this is given by hubbles law

Question 22

We have detected galaxies from when the universe was only ________ years old

Answer 22

1 to 2 billion years old

Question 23

Physical cosmology

Answer 23

The use of the laws of physics to study the formation and fate of the universe

Question 24

The early universe must have been _______

Answer 24

hot and dense

Question 25

Known forces in the universe

Answer 25

• Gravity
• strong force
• electromagnetism
• weak force

Question 26

Plank era lasted

Answer 26

10^-43

Question 27

Gut era lasted

Answer 27

less than a trillion trillion trillionth of a second

Question 28

We have detected leftover ______ from the big bang theory

Answer 28

radiation

Question 29

WMAP gives us ________

Answer 29

detailed pictures of the universe

Question 30

How old is the universe?

Answer 30

13.7 billion years old

Question 31

An undetected form of mass that emits little or no light, but whose existence we infer from its gravitational infulence

Answer 31

Dark matter

Question 32

An unknown form energy that seems to be the source of a repulsive force causing the expansion of the universe to accelerate

Answer 32

Dark energy

Question 33

A plot of orbital velocity, v, versus orbital radius, r,

Answer 33

rotation curve

Question 34

A galaxy cluster is made up of:

Answer 34

85% dark matter
13% hot gas
2% stars

Question 35

Three methods of measuring a clusters mass:

Answer 35

• galaxy motions
• x-ray gas temp
• gravitational lensing

Question 36

(MACHOS) Ordinary dark matter:

Answer 36

dead or failed stars in halos of galaxies

Question 37

(WIMPS) extraordinary dark matter:

Answer 37

mysterious neutrino-like particles