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Astronomy > FINAL EXAM > Flashcards

FINAL EXAM Flashcards

1
Q

Imagine a line going through Earth, connecting the North and
South Poles. Earth rotates about
this line.

A

Earths Axis

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2
Q

If we extend the Earth’s axis what are the points where it connects with the celestial sphere?

A

North & South celestial pole

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3
Q

the equator of the celestial sphere is called the

A

Ecliptic

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4
Q

Planetary orbits are ellipses, with the Sun at one focus

A

Keplers First Law

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5
Q

path of an object
through space

A

orbit

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6
Q

one of the two
foci

A

focus

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7
Q

The imaginary line connecting Sun and planet sweeps out
equal areas in equal times.

A

Keplers Second Law

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8
Q

the speed of an orbiting planet (or moon or satellite) will change depending where it is in the orbit is called what

A

consequence

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9
Q

Square of period of planet’s orbital motion is proportional to cube of semi-major axis.

A

Keplers Third Law

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10
Q

the time it takes a
planet to travel once around
the Sun

A

Period

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11
Q

the average distance between
Earth and the Sun

A

1 AU

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12
Q

an excitation that propagates through space or a medium

A

wave

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13
Q

sound waves, water waves governed by Newton’s laws exist with a medium

A

Mechanical waves

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14
Q

light, radio waves, microwaves can travel in a vacuum (don’t need a medium to propagate) travel with velocity c = 2.99x108 m/s, which is the speed of light

A

Electromagnetic waves

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15
Q

maximum departure of a wave from the undisturbed state

A

Amplitude

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16
Q

number of meters needed for the wave to repeat itself at a given
moment in time

A

Wavelength

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17
Q

number of seconds needed for a wave to repeat itself at some point
in space

A

period

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18
Q

number of crests passing a given point per unit time

A

frequency

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19
Q

frequency = ?

A

1 / Period

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20
Q

The energy ux from a blackbody at temperature T is proportional to the
fourth power of its absolute temperature. This relationship is known as the

A

Stefan-Boltzmann law

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21
Q

The location of the spectral peak (or maximum) in the power curve of each star
can tell us its temperature

A

Wiens Law

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22
Q

______ allow us to collect
the radiation and focus it on
detectors where we can store
and analyze it

A

Telescopes

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23
Q

Types of telescopes

A

Radio, Infrared, optical, UV, x-ray, gamma rays

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24
Q

____ needs two optically acceptable surfaces, _____ only needs one: easier to make mirrors

A

Lens; Mirror

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25
Q

_______’s use mirrors or lenses to collect light

A

Optical Telescopes

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26
Q

Because this array of colors is a spectrum of light, the instrument used to
disperse the light and form the spectrum is called a

A

spectrometer

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27
Q

____ is the building block of all matter

A

atom

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28
Q

Surrounding the nucleus, there are ____ negatively charged

A

electrons

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29
Q

_______ are due to the discrete (quantum) spacing of an atom’s electron
energy levels

A

spectral lines

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30
Q

What event emits a photon of a discrete energy equal to the difference of the energy levels

A

Electron de-excites

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31
Q

an array of all wavelengths or colors of the
rainbow.

A

Continuous spectrum

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32
Q

appears as a pattern or series of bright lines; it consists of light in which only certain discrete wavelengths are present

A

emission spectrum

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33
Q

If a continuous spectrum passes through a
cool gas, atoms of the gas will absorb the same frequencies they emit
when excited describes what?

A

Absorption Spectrum

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34
Q

From sun (source of continuous spectrum) to a cloud of gas with few absorption lines results in _____. From cloud of gas with predominantly absorption lines results in ___. Straight from sun to _____ spectrum with no absorption lines

A

Absorption spectrum, emission spectrum, continuous spectrum

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35
Q

To measure stellar parallax use position of Earth in January (A)/July(B)

A

Parsec

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36
Q

Referring to parsecs: d (distance) =

A

s / angle

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37
Q

d(parsec) =

A

1 / (angle * arcseconds)

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38
Q

The magnitude equation is:

A

apparent magnitude - absolute magnitude = 5log(distance / (10pc)

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39
Q

What is the difference between apparent and absolute magnitude of a star 100 pc away?

A

5

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40
Q

A star has an apparent magnitude 10.0 and an absolute magnitude 2.5.
How far away is it?

A

316pc

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41
Q

Name the categories of stellar spectra:

A

O B A F G K M (Oh Be A Funny Goat, Kick Me)

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42
Q

Intrinsic Variable Stars Used for Distance are _____ & ________

A

Cepheid & RR Lyrae stars

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43
Q

____ stars have
essentially the same luminosity curve, with
periods from 0.5 to 1 day.

A

RR Lyrae

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44
Q

________ periods range from about 1 to 100
days.

A

Cepheid Variables

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45
Q

______ all have about the same
luminosity; knowing their apparent
magnitude allows us to calculate the
distance

A

RR Lyrae Stars

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46
Q

______ have a luminosity that is
strongly correlated with the period of
their oscillations; once the period is
measured, the luminosity is known and
we can proceed as above

A

Cepheids

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47
Q

___ gas is found in Emission
nebulae: hot, glowing area associated with the
formation of large stars.

A

ionized hydrogen(H*)

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48
Q

Found in cold regions
without stars between dust clouds

A

atomic hydrogen(H)

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49
Q

Found in cold dark
dust clouds

A

Molecular hydrogen(H2)

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50
Q

______ are composed of atomic
hydrogen gas that is ionized by near-by stars and are located in which region

A

emission nebulae; HII

51
Q

____ plots stellar luminosity versus surface temperature

A

HR Diagram

52
Q

This region is
where star formation occurs

A

molecular hydrogen

53
Q

The darkened curve on the HR Diagram is called the ____, as this is where most stars are

A

Main sequence

54
Q

these stars are hot but not very luminous, as they are quite small

A

White Dwarfs

55
Q

the brightest stars in the sky appear bright because of their

A

enormous luminosities and not their proximity

56
Q

____ giants are toward the start of the main sequence

A

blue

57
Q

____ giants are above the end of the main sequence

A

red

58
Q

____ percent of stars lie on
the main sequence

A

90

59
Q

___ percent of stars are red giants

A

9

60
Q

___ percent of stars are white dwarves

A

1

61
Q

_____ lie under the main sequence

A

White dwarfs

62
Q

On the HR diagram, The shape of the paths is similar, but they wind up in
different places on the main
sequence depending on their

A

Mass

63
Q

____ causes a star to burn hydrogen in the surrounding shell.The core contracts and heats; the outer atmosphere expands and cools.

A

Once hydrogen is gone

64
Q

Helium begins to fuse in the core & The star expands into a red giant as the core
continues to collapse describes what

A

Helium Flash

65
Q

Only stars with a end life mass of less than 1.4 times the mass of the Sun (called
_____________) will end their cycle as white dwarfs

A

Chandrasekhar limit

66
Q

The collapsing core can reach a stable state as a crushed ball made mainly of neutrons, which astronomers call a

A

neutron star

67
Q

loose, irregular cluster, found mainly
in the plane of the Milky Way

A

open cluster

68
Q

spherical cluster of stars with the
absence of massive main-sequence stars, and the heavily
populated red giant region. Found away from the galactic
plane.

A

globular cluster

69
Q

________ Galaxies - no spiral arms and no disk

A

Elliptical

70
Q

____ galaxies show various degrees of flattening, ranging from systems that
are approximately spherical to those that approach the flatness of spirals.

A

Elliptical

71
Q

Star classification that have a disk and bulge, but no spiral arms, no interstellar gas. In between
ellipticals and spirals.

A

SB & SBO

72
Q

______ galaxies have a wide variety of shapes. Undergoing interactions with other galaxies.

A

Irregular

73
Q

very powerful and compact sources of energy at the centers of distant galaxies

A

quasar

74
Q

_____ type galaxies are generally elliptical and lenticular (S0) galaxies

A

Early

75
Q

____ type galaxies are spiral and irregular galaxies

A

late

76
Q

Name the equation: v = H * d

A

Hubbles Law

77
Q

Age of the Universe of about

A

13.8 billion years

78
Q

Name the principle: the Universe is both homogeneous and isotropic

A

Cosmological

79
Q

The fate of the universe (the old theory)

A

slow expansion or decelerate back to the beginning

80
Q

The fate of the universe (the new theory)

A

The universe is expanding rapidly due to dark energy

81
Q

Arno Penzias and Robert Wilson observed the big bang known as the

A

Cosmic background Radiation

82
Q

____ percent of stuff in the universe is made of dark matter and dark energy

A

95

83
Q

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

A

age of the universe

84
Q

T OR F: If the expansion of the universe were accelerating, it would mean that distant Type Ia supernovae would look fainter than we would expect from measuring their redshifts and applying Hubble’s law.

A

True

85
Q

T OR F: As the universe expands, the temperature throughout the universe increases regularly

A

False

86
Q

T OR F: All the evidence currently suggests that we live in closed universe

A

False

87
Q

T OR F: The latest conclusion that astronomers have reached about the expansion of the universe is that the rate at which space is expanding is decelerating – that is, the expansion is slowing down due to the pull of gravity.

A

False

88
Q

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?

A

the measurement of galaxy distances using white dwarf (type Ia) supernovae

89
Q

According to the Cosmological Principle, the universe is _____ & ______

A

isotropic and homogeneous

90
Q

Roughly how many galaxies make up our Local Group?

A

About 60 or so

91
Q

What cluster is Earth located in

A

Virgo Supercluster

92
Q

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

A

Elliptical

93
Q

In which type of galaxy are you likely to observe a significant amount of star formation?

A

Spiral irregular

94
Q

Hubbles constant is around ____ kilometers a second

A

70

95
Q

Our Milky Way Galaxy is what type of galaxy?

A

spiral

96
Q

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:

A

elliptical

97
Q

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

A

their shape

98
Q

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

A

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

99
Q

Which of the following objects is considered useful to astronomers as a “standard candle” for determining distances?

A

White dwarf

100
Q

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

A

faster it is moving away from us

101
Q

To calculate the redshift (𝑧) of the quasar, we can use the following formula for redshift:

A

(observed - rest) / rest

102
Q

When a quasar is moving away from us at a significant fraction of the speed of light, we can use the relativistic redshift formula to calculate the redshift (𝑧):

A

sqrt((1+B) / (1-B)) - 1

(B = v/c)

103
Q

gas and dust that lie between stars

A

interstellar matter

104
Q

reflection nebulae have a ____ cast as their interstellar dust grains preferentially reflect _____ starlight (Hint: answer is a color)

A

Blue

105
Q

a zone around a hot star where hydrogen atoms are ionized

A

HII Region

106
Q

The red color we see on a lot of photographs of nebulae comes from which element?

A

hydrogen

107
Q

Which of the following types of star is the coolest (has the lowest surface temperature)?

A

M

108
Q

How to calculate parallax

A

d = 1 / p (parallax angle)

109
Q

T OR F: The amount by which the spectral lines of a star is redshifted tells astronomers how fast the star is moving away from us.

A

True

110
Q

The formula relating distance, apparent brightness (also called flux), and luminosity is

A

apparent brightness = luminosity / (4π * distance^2)

111
Q

which planets revolve around the Sun in the same direction

A

All of them

112
Q

T OR F: jovian planets (being larger) rotate significantly more slowly than terrestrials

A

FALSE

113
Q

what do all four terrestrial planets have in common?

A

they all have solid surfaces with signs of geological activity on them 

114
Q

The region around the Earth where charged particles are trapped and spiral around is called the ____ sphere

A

magneto

115
Q

T OR F: a comet always has a nice long tail, even when it is far from the Sun

A

FALSE

115
Q

what wave has the longest wavelength?

A

radio waves

116
Q

T OR F: For all electromagnetic waves, the frequency multiplied by the wavelength will be the same constant number.

A

FALSE

117
Q

Which ancient Greek thinker suggested (long before Copernicus) that the Earth is moving around the Sun?

A

Aristarchus

118
Q

T OR F: At the Earth’s equator, you would see the celestial poles on your horizon.

A

TRUE

119
Q

A star is 230 light-years away. The light we see tonight from that star left it

A

230 years ago

120
Q

The point in the sky directly above your head at any given time is called the

A

zenith

121
Q

T OR F: The path that the Sun appears to make in the sky over the course of a year is called the celestial equator.

A

FALSE

122
Q

The scientist who first devised experimental tests to demonstrate the validity of the heliocentric model of the solar system was

A

Galileo

Astronomy (3 decks)

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