chapter 18 Review

Question 1

The ________ is the totality of all matter, energy, and space.

Answer 1

Universe

Question 2

the huge imaginary sphere of the sky on which all the stars seem to be located is the __________

Answer 2

celestial sphere

Question 3

A ________ is the distance (3.26 ly) to an object with a parallax of 1 arc second.

Answer 3

parsec

Question 4

The layer of the sun that we see is the ________

Answer 4

photosphere

Question 5

_____________ is a measure of the brightness of a star as seen from earth.

Answer 5

Apparent magnitude

Question 6

________ is a measure of the brightness of a star if I we seen from a standard distance of 10 pc (32.6 ly).

Question 7

The band of stars from the upper left to the lower right in above plot that most stars fall into is the ____________.

Answer 7

main sequence

Question 8

The relatively cool bright stars with diameters 10-100 times that of the sun are the __________

Answer 8

red giants

Question 9

________ are cool denser clouds of interstellar gas and dust

Answer 9

nebula

Question 10

The shell of gas ejected from an old low mass stairs a __________

Answer 10

planetary nebula

Question 11

A white dwarf star that suddenly increases dramatically in brightness for a brief period of time is a ____________

Answer 11

nova

Question 12

when a star explodes it is a ___________

Answer 12

super nova

Question 13

All elements heavier than _______ are made in _______ explosions.

Answer 13

iron, supernova

Question 14

A _______ is The extremely dense remnant of a high mass star that is made of neutrons

Answer 14

neutron star

Question 15

A rapidly rotating that appears to pulse on and off is called a __________

Answer 15

pulstar

Question 16

A large gravitationally bound collection of stars and gas is a _________

Answer 16

galaxy

Question 17

Galaxies come in 3 types

Answer 17

elliptical
spiral
irregular

Question 18

The additional mass required the keep galaxies gravitationally bound that we cannot see is called ________.

Answer 18

black matter

Question 19

The study of the structure and history of the the entire universe is

Answer 19

cosmology

Question 20

Hubble’s law say the further away a galaxy is the _________ it is travelling away from us

Answer 20

faster

Question 21

The force accelerating the expansion of the universe is called

Answer 21

energy

Question 22

The universe is expanding because the __________ itself is expanding.

Answer 22

space

Question 23

The _______Theory of the beginning of the universe states that the known universe was smaller, hotter, and denser in the past, and that it began rapidly expanding 13.8 billion years ago.

Answer 23

Big Bang

Question 24

What is the point on the celestial sphere representing the extension of the axis of Earth’s North Pole?

Answer 24

North celestial pole

Question 25

What is the name of the path on the sky that the Sun appears to follow as it moves among the stars?

Answer 25

the ecliptic

Question 26

Define the term cosmology.

Answer 26

The branch of astronomy that is the study of the structure and evolution of the universe.

Question 27

Which is the larger unit of distance, the light-year or the parsec?

Answer 27

the parsec

Question 28

Why are sunspots darker than the regions of the Sun around them?

Answer 28

They are cooler than the surrounding material.

Question 29

Where in the Sun does fusion of hydrogen occur?

Answer 29

only in the core

Question 30

What is the approximate temperature (in K) of the Sun at its surface?

Answer 30

6,000 K

Question 31

A relatively cool star is what color?

Answer 31

red

Question 32

Which star is closest to the Sun?

Answer 32

Proxima Centauri

Question 33

A white dwarf has about the same diameter as which of the following? the Earth Texas the Sun Jupiter

Answer 33

the Earth

Question 34

How big will the Sun become as a red giant star?

Answer 34

It will engulf the orbits of Mercury, Venus and possibly the Earth.

Question 35

Define the term nucleosynthesis.

Answer 35

the creation of nuclei inside stars

Question 36

Describe how the mass of a star plays a role in the lifetime of a star.

Answer 36

The more massive the star, the shorter the lifetime.

Question 37

What is the fundamental quantity of a star that indicates its ultimate fate?

Answer 37

Mass

Question 38

What event is believed to create elements heavier than iron?

Answer 38

a supernova explosion

Question 39

What is dark matter?

Answer 39

unknown exotic matter

Question 40

How much of the universe appears to be normal ordinary matter?

Answer 40

5%

Question 41

What is the cosmic background radiation?

Answer 41

the light-energy remnants of the explosion in which the universe was born

Question 42

What key observation led Hubble to conclude that the universe is expanding?

Answer 42

the redshift of light from distant galaxies

Question 43

What is the galaxy classification of the Milky Way galaxy?

Answer 43

barred spiral galaxy

Question 44

What is a quasar?

Answer 44

The core of a young very active galaxy observed when the universe was very young.

Question 45

The Milky Way is classified as what kind of galaxy?

Answer 45

spiral

Question 46

Black holes appear black for what basic reason?

Answer 46

Light cannot escape them.