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Astronomy Midterm > Astronomy Midterm > Flashcards

Astronomy Midterm Flashcards

(105 cards)

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1
Q

Which of the following has your “address” in the correct order?

A

You, Earth, solar system, Milky Way, Local Group, Local super cluster

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2
Q

What is an astronomical unit?

A

The average distance from earth to the sun

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3
Q

Roughly how many stars are in the milky way galaxy?

A

100 billion

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4
Q

Which of the following statements about the celestial sphere is not true?

A

The celestial sphere is just another name for our universe

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5
Q

Which of the following statements about the celestial equator is true at all latitudes?

A

It represents an extension of earths equator onto the celestial sphere

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6
Q

How many stars can you see with your naked eye on a clear, moonless night from a dark location?

A

A few thousand

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7
Q

What is the ecliptic?

A

The suns apparent path along the celestial sphere

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8
Q

Which scientist played a major role in overturning the ancient idea of an Earth centered universe, and about when?

A

Copernicus, Kepler, and Galileo; about 400 years ago

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9
Q

Which of the following correctly describes the meridian in your sky?

A

A half circle extending from your horizon due east, through your zenith, to your horizon due west

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10
Q

How many arcseconds are in 1 degree?

A

3600

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11
Q

Which of the following statements does not use the term angular size or angular distance correctly?

A

The angular distance between those two bright stars in the sky is about 2 meters

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12
Q

What is a circumpolar star?

A

A star that always remains above your horizon

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13
Q

We describe a position on earth’s surface by stating it’s

A

Latitude and longitude

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14
Q

What makes the North Star, Polaris, special?

A

It appears very near the north celestial pole

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15
Q

Orion is visible on winter evenings but not summer evenings because of

A

The location of earth in its orbit

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16
Q

Which of the following is not a phase of the moon?

A

Half moon

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17
Q

If the moon is setting at 6 AM, the phase of the moon must be

A

Full

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18
Q

Which of the following never goes in retrograde motion?

A

Venus

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19
Q

How did Eratosthenes estimate the size of Earth in 240 B.C.?

A

By comparing the maximum altitude of the sun in two cities at different latitudes

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20
Q

Why did Ptolemy have the planets orbiting Earth on “circles upon circles” in his model of the universe?

A

To explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky

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21
Q

Where was the sun in ptolemy’s model of the universe?

A

Between the orbits of Venus and mars

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22
Q

The controversial book of this famous person, published in 1543 (the year of his death), suggested that earth and other plants orbit the sun

A

Copernicus

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23
Q

He discovered that the orbits of planets are ellipses

A

Kepler

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24
Q

He discovered that Jupiter has moons

A

Galileo

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25
from Kepler’s third law, an asteroid with an orbital period of 8 years lies at an average distance from the sun equal to
4 astronomical units
26
What is meant by a hypothesis?
An explanation for a phenomenon that makes a prediction
27
Which of the following was not observed by Galileo?
Stellar Parallax
28
If your mass is 60 kg on earth, what would your mass be on the moon?
60 kg
29
What would happen if the space shuttle were launched with a speed greater than earths escape velocity?
It would travel away from earth into the solar system
30
The movement of a pool ball, rolling on a table at constant velocity, is an example of
Newton’s first law of motion
31
The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them
Weakens by a factor of 4
32
According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will
Increase by a factor of 4
33
The mass of Jupiter can be calculated by
Measuring the orbital period and distance of one of Jupiter’s moons
34
At which lunar phase(s) are tides most pronounced?
Both new and full moons
35
An atom in an excited state contains more of what type of energy than the same atom in the ground state?
Electric potential energy
36
If a material is highly opaque, then it
Absorbs most light
37
The wavelength of a wave is
The distance between two adjacent peaks of the wave
38
How are wavelength, frequency, and energy related for photons of light?
Longer wavelength means lower frequency and lower energy
39
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
Radio, infrared, visible light, ultraviolet, X rays, gamma rays
40
When an atom loses an electron, it becomes
Ionized
41
When an electron in an atom goes from a higher energy state to a lower energy state, the atom
Emits a photon of a specific frequency
42
If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits
81 times more energy
43
The spectra of most galaxies show redshifts, this means that their spectral lines
Have wavelengths that are longer than normal
44
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?
The star is moving away from us
45
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: think about the laws of thermal radiation)
The blue star has a hotter surface temperature than the red star
46
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects
Extreme infrared
47
Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?
The two stars will look like a single point of light
48
Which of the following statements best describes the two principal advantages of telescopes over eyes?
Telescopes can collect far more light with far better angular resolution
49
What do astronomers mean by light pollution?
Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations
50
Which of the following is not an advantage of the Hubble space telescope over ground- based telescopes?
It is closer to the stars
51
In what part of the electromagnetic spectrum do the biggest telescopes on earth operate?
Radio
52
How do asteroids differ from comets?
Asteroids are rocky bodies and are denser than the comets, which are made of icy material
53
How does the sun’s mass compare to that of the planets?
It is a thousand times more massive than all the planets combined
54
Which planet has the highest average surface temperature, and why?
Venus, because of its dense carbon dioxide atmosphere
55
Which planet, other than earth, has visible water ice on it?
Mars
56
Which of the following is furthest from the sun?
A comet in the Oort Cloud
57
Which of the following is not an exception to the general patterns of motion in the solar system?
The rings of Saturn
58
Which is the densest planet in the solar system?
Earth
59
The planet closest in size to earth is
Venus
60
Which of the following is not a characteristic of the inner planets
They all have substantial atmospheres
61
Which of the following is not a characteristic of the outer planets?
They have very few, if any, satellites
62
What is aerobraking?
The technique of using a planetary atmosphere to change the orbit of a spacecraft
63
Which of the following is not an advantage of spacecraft flybys over ground based telescope observations?
Spacecraft can make highly detailed images of the planet and its moons
64
Why did the solar nebula heat up as it collapsed?
As the cloud shrank, it’s gravitational potential energy was converted to kinetic energy and then into thermal energy
65
What percentage of the solar nebula’s mass consisted of rocky material?
0.4 percent
66
What kind of material in the solar nebula could remain solid at temperatures as high as 1,500 K, such as existed in the inner regions of the nebula
Metals
67
What was the frost line of the solar system?
The distance from the sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present day orbits of mars and Jupiter
68
According to the nebular theory, what are asteroids and comets?
They are leftover planetesimals that never accreted into planets
69
The heavy bombardment phase of the solar system lasted
Several hundreds of millions of years
70
The nebular theory of the formation of the solar system successfully predicts all but one of the following. Which one does the theory not predict?
The equal number of terrestrial and Jovian planets
71
Rank the five terrestrial worlds in order of size from smallest to largest:
Moon, Mercury, mars, Venus, earth
72
Which of the following most likely explains why Venus does not have a strong magnetic field?
It’s rotation is too slow
73
Which two properties are most important in determining the surface temperature of a planet?
Distance from the sun and atmosphere
74
Which of the following does not have a major effect in shaping planetary surfaces?
Magnetism
75
The relatively few craters that we see within the lunar Maria
Were formed by impacts that occurred before those that formed most of the craters in the lunar highlands
76
The caloris basin on Mercury covers a large region of the planet, but few smaller craters have formed on top of it. From this we conclude that
The caloris basin formed toward the end of the solar systems period of heavy bombardment
77
Olympus mons is a
Shield volcano on mars
78
Why does Venus have such a great difference in temperature between its “no atmosphere” temperature and it’s actual temperature?
It has a large amount of greenhouse gases in its atmosphere
79
What are greenhouse gases
Gases that absorb infrared light
80
There are no aurora on Venus because it
Lacks a strong magnetic field
81
Where is most of the water on mars?
In its polar caps and subsurface ground Ice
82
Why is mars red?
Its surface rocks were rusted by oxygen
83
How does Jupiter’s core compare to earth’s?
It is about the same size but is 10 times more massive
84
The fact that most moons always show the same face to their planet is
A natural consequence of tidal forces acting on the moons
85
What is the most important reason why an icy moon is more likely to be geologically active than a rocky moon of the same size?
Ice has a lower melting point than rock
86
Why is Jupiter denser than Saturn?
The extra mass of Jupiter compresses its interior to a greater extent than that of Saturn
87
What is Jupiter’s Great Red Spot?
A long-lived, high pressure storm
88
The four Galilean moons around Jupiter are
A mixture of rock and ice, with the ice fraction increasing with distance from Jupiter
89
Why are there no impact craters on the surface of Io?
Io did have impact craters but they have all been buried in lava flows
90
Which moon has the most substantial atmosphere?
Titan
91
How thick are Saturn’s rings from top to bottom?
A few tens of meters
92
Which is closest to the average distance between asteroids in the asteroid belt?
1 million Km
93
Why isn’t there a planet where the asteroid belt is located?
Gravitational tugs from Jupiter prevented material from collecting together to form a planet
94
What do we call a small piece of solar system debris found on earth?
Meteorite
95
Halley’s Comet is named after the English scientist Edmund Halley because he
Calculated its orbit and predicted that it would return in 1758
96
What part of a comet points most directly away from the sun?
The plasma tail
97
Most of the five planets discovered around other stars
Are more massive than earth and orbit very close to the star
98
What is astrometry?
Measuring the positions of stars on the sky
99
Current techniques can measure stellar motion to less than
Walking speed
100
Why are many of the newly detected extrasolar planets called “hot jupiters”?
Their masses are similar to Jupiter but they are very close to the central star and therefore hot
101
The core of the sun is
Hotter and denser than the surface
102
What two forces are balanced in what we call gravitational equilibrium?
Outward pressure and gravity
103
What is the average temperature of the surface of the sun?
6,000 K
104
Which layer of the sun do we normally see?
Photosphere
105
At the center of the sun, fusion converts hydrogen into
Helium, energy, and neutrinos

Astronomy Midterm (1 decks)

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