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Exploring the Universe > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Write 23,500 in scientific notation:

A

2.35 x 10^4

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2
Q

Write the number that corresponds to the following scientific notation 3 x 10^-3

A

0.003

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3
Q

Knowing that y=32, what is the value of x?
Y = 3x

A

X = 10.67

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4
Q

Knowing that y=32 and c=345, what is the value of x?

A

X=0.093

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5
Q

Knowing that x=20, what is the value of y?
Y=3x^3

A

Y=24,000

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6
Q

Study of the objects that lie beyond our planet and the processes by which these objects interact with one another

A

Astronomy

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7
Q

Science that studies the physical laws involved in the processes of formation and evolution of everything in the universe

A

Astrophysics

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8
Q

79,200,000,000 in scientific notation is written as:

A

7.92 x 10^10

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9
Q

Is a unit of distance

A

Light year (lay)

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10
Q

Why do we say light year?

A

Because we know the speed of light, so, knowing how many years it takes the light to go from one point to another we know how much space it traveled

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11
Q

How long does it take for the moon to revolve around the earth?

A

1 month (28 days)

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12
Q

How many times have you gone around the sun?

A

About ~ my age

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13
Q

What is a star?

A

Gigantic ball of gas that generates enormous amounts of energy by nuclear reactions that happen inside them

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14
Q

Is a disk galaxy, with a bar and a small bulge

A

The Milky Way

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15
Q

How far is the Milky Way?

A

100,000 light-years

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16
Q

Material in-between stars

A

Interstellar material

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17
Q

Blocks the visible light of more distant stars, luckily it doesn’t block their light in the infrared!

A

Dust is a light eater

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18
Q

Matter that we cannot see

A

Dark matter

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19
Q

Do stars live alone or in groups?

A

Some stars live alone: like the sun

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20
Q

Regions where many stars were born together and contain hundreds of thousands of stars and take up volumes of space hundreds of light-years across

A

Star clusters

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21
Q

Are star clusters A) larger or B) smaller than our galaxy?

A

Smaller

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22
Q

Going further out what can we find?

A
  • Isolated (on their own)
  • In groups (with a few other galaxies)
  • In clusters (with thousands of galaxies)
  • In super clusters (these contains clusters, groups, and galaxies in isolation)
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23
Q

Are all the galaxies discovered already?

A

Not even close!

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24
Q

What are quasars?

A
  • Extremely bright centers of galaxies
  • Brightness is generated by gas that gets heated as it falls into the black hole at the center of the galaxy and swirls around it
  • We see quasars as far as 10 or more billion light-years, which is looking 10 billion years in the past
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25
Q

What’s the closet galaxy to the Milky Way (that is not a satellite)?

A

Andromeda

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26
Q

What are dwarf galaxies?

A

Galaxies less massive than our own galaxy

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27
Q

How does everything look from our perspective?

A
  • Everything moves around us
  • But earth is not at the center of anything!
  • Stars, as the sun, and moon, rise from the east and set on the west
  • It seems that the sky is a spere that turns around us
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28
Q

What is the celestial sphere?

A
  • But, it is not the sky that turns, but us that move!
  • Because the earth turns on it axis every 24h, we see celestial objects rise and set
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29
Q

Stars that never rise or set

A

Circumpolar stars

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30
Q

Is there a place on earth where you can theoretically see all the stars in the sky?

A

Yes, from the equator

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31
Q

Do stars move during day time?

A

Yes

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32
Q

Path the sun appears to take around the celestial sphere each year

A

Ecliptic

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33
Q

What else is in the same plane of the sun?

A

Anything on that plane will move on the ecliptic

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34
Q

Why does the height of the north celestial pole vary from one image to the next?

A

Latitude of site has changed

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35
Q

What are constellations useful for?

A
  • Navigation
  • Calendar
  • Naming locations in the sky
  • Mythology
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36
Q

1 actual earth rotation relative to distant (“fixed”) stars

A

Sidereal day

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37
Q

1 earth rotation relative to sun (noon to noon)

A

Solar day

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38
Q

Which is longer: solar or sidereal day?

A

Solar

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39
Q

Which day is on our clocks, calendars?

A

Solar = 24hrs

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40
Q

Path of an object through space

A

Orbits

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41
Q

The orbits of all planets are ellipses and the sun is at one focus of the ellipse

A

First law

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42
Q

The straight line joining a planet and the sun sweeps out equal areas in space in equal intervals of time

A

Second law

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43
Q

The orbital period of planet squared is equal to the semimajor axis of its orbit cubed (if the period is in years and the semimajor axis is in astronomical units)

A

Third law

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44
Q

Is time the planet takes to travel once around the sun

A

Orbital period P

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45
Q

Average distance from the sun

A

Semimajor axis a

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46
Q

Can planets have circular orbits according to Kepler’s law?

A

Yes, the circle is a special case of an ellipse, that with ellipticity = 0

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47
Q

An asteroid with an orbital period of 8 years lies at an average distance from the sun equal to

A

4 astronomical units

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48
Q

Rate at which object moves

A

Speed

49
Q

Speed and direction

A

Velocity

50
Q

Any change in velocity unites of speed/time (m/s^2)

A

Acceleration

51
Q

Every object will continue to be in a state of rest or move at a constant speed in a straight line unless it is compelled to change by an outside force

A

Newton’s First Law

52
Q

The change of motion of a body is proportional to and in the direction of the force acting on it

A

Newton’s Second Law

53
Q

Mass X Acceleration

A

Force

54
Q

For every force, there is always and equal and opposite force

A

Newton’s third law

55
Q

Amount of matter in an object

A

Mass

56
Q

Force that acts upon an object due to gravity

A

Weight

57
Q

On the Moon my weight…

A

Is less, my mass is the same

58
Q

How does the force the earth exerts on you compare with the force you exert on it?

A

Earth and you exert equal and opposite forces on each other

59
Q

On Mars, if two bricks with the same geometry are released from a tower, one with 2 pounds and one with .05 pounds, the 2 pound brick hits the ground first

A

False, they will reach the ground together

60
Q

Describe the motion in a straight line

A

Newton’s laws of motion

61
Q

Kepler found that planets move in ellipses, what’s bending their path?

A

Gravity

62
Q

Newton’s universal law of gravitation…

A
  • Every mass attracts every other mass
  • Attraction is directly proportional to the product of their masses
  • Attraction is inversely proportional to the square of the distance between their centers
63
Q

Is any circle on the surface of a sphere whose center intersects the center of the sphere

A

Great circle

64
Q

Is the number of degrees of arc you are away from the equator along your meridian

A

Latitude

65
Q

Is the equivalent of longitude and declination is the equivalent of latitude

A

Right-ascension

66
Q

The point where the ecliptic crosses the celestial equator

A

Equinox

67
Q

How does the sun favoring one of the hemisphere translate into more or less warmth?

A
  • If a hemisphere “leans” towards the sun the light rays hit on a more straight angle and “diffuse” the light less
  • The length of time the sun spends above the horizon
68
Q

The equator defines the zero-th degree of

A

Latitude (N-S)

69
Q

The Sun’s altitude on the sky depend on?

A

Latitude of the place + time of the year

70
Q

In the north hemisphere, days are shorter in winter and longer in summer. In the southern hemisphere?

A

Same than in the north: days are longer in summer but shorter in winter

71
Q

Occurs whenever any part of either earth or the moon enter the shadow of the other

A

Eclipse

72
Q

If an eclipse of the sun occurs when the moon is somewhat nearer than its average distance, the moon can completely hid the sun

A

Total solar eclipse

73
Q

The moon phases

A

Are the same from every point on earth

74
Q

A solar eclipse occurs when

A

The moon blocks sunlight from reaching the earth

75
Q

Occurs when the moon enters the shadow of the earth

A

Lunar eclipse

76
Q

How big is earth’s dark shadow?

A

1.4 million kilometers long

77
Q

Who can see the lunar eclipse?

A

Is visible to everyone who can see the moon

78
Q

What is beyond Neptune?

A
  • The orbit of the 8 plants are more or less well aligned into a single place, providing clues to the origin of the solar system
  • celestial bodies like these dwarf planets are referred to as “trans neptunian objects” (TNOs)
79
Q

Mass/volume

A

Density

80
Q

How do we determine masses?

A

From their gravitational effects on nearby objects

81
Q

What are the three major goals of the Apollo missions?

A
  • The astronauts collected nearly 400 kg of samples (~ 882 pounds) for detailed laboratory analysis on Earth. These samples have revealed as much about the Moon and its history as all other lunar studies combined.
  • Each Apollo landing after the first one deployed an Apollo Lunar Surface Experiment Package (ALSEP), which continued to operate for years after the astronauts departed.
  • The orbiting Apollo command modules carried a wide range of instruments to photograph and analyze the lunar surface from above.
82
Q

How long ago was the earth and moon formed?

A

4.5 and 4.6 billion years ago

83
Q

Involved the release of lava from hundreds of kilometers below the surface, ended about 3.3 billion years abgo

A

The major mare volcanism

84
Q

What is the cratering process?

A
  • The impact occurs
  • The projectile vaporizes and a shock wave spreads through the lunar rock
  • Ejecta are thrown out of the crater
  • Most of the ejected material falls back to fill the crater, but some of it is found outside the crater in the form of an ejecta blanket
85
Q

The Moon’s chemical composition is:

A

Very different from Earth because is high in light silicates and is missing most heavy metals

86
Q

The origin of most craters on the Moon is:

A

External impacts, as solar system bodies crashed on the Moon

87
Q

The Moon was formed:

A

Approximately at a similar time than Earth, 4.5-4.6 billion years ago

88
Q

How is the surface in Venus like?

A
  • We cannot see the surface, but imagining radar maps gives us information on the geology of Venus
  • Similar appearance to earth in terms of elevations or valleys, but no evidence of tectonic plates
89
Q

How is the temperature in Venus?

A

Very hot! ~700 K

90
Q

How does the “daylight” look in Venus:

A

It is similar to Earth in terms of landscape, but it is quite dark even during daytime because of the atmosphere

91
Q

Mars suffers of intense dust storm, with continent-sized dusty patches that can be detected even from telescopes on Earth. Once every ~5 years a dust storm may grow enough to engulf the whole planet. What does this means for possible future missions with astronauts:

A

It will get uncomfortable, but the thins atmosphere on Mars prevent these storms from making real damage

92
Q

What are some challenges of space exploration for giant planets?

A
  • Flight times are measured in years to decades (compound to months for Venus or mars)
  • Messages take hours to pass between earth and the spacecraft. Need machines with great independice and autonomy
  • Outer solar system missions must carry their own power source (Sun is far)
  • Heaters are required to keep instruments at proper operating temperatures
  • Spacecraft must have powerful radio transmitters to send their data to receivers on earth
93
Q

How is Jupiter?

A
  • ~5 AU from the sun
  • 1 year = 12 earth years
  • 320x mass of earth
  • No solid surface
  • Made mostly of H and He
  • Bands and “swirls” caused by large weather patterns
  • At least 60 moons!!
94
Q

What are the bands on Jupiter?

A

The bands on Jupiter move at different speeds

95
Q

How is Saturn?

A
  • ~9.5 AU from the sun
  • 1 year = 29 earth years
  • 95x mass of earth
  • No solid surface
  • Made mostly of H and He
  • Bands ands “swirls” caused by large weather patterns
  • 31 moons
96
Q

Giant planets are:

A

More massive and more extended than the terrestrial planets

97
Q

The colorful bands on the giant planets are a consequence of:

A

Weather patters moving at different speeds and interacting with one another

98
Q

How do the length of the years (1 revolution around the sun) compare:

A

Earth < Jupiter < Saturn

99
Q

When was Uranus discovered?

A

1781

100
Q

Are created as tiny solid particles that enter Earth’s atmosphere from interplanetary space

A

Meteors

101
Q

Because meteros move fast, the friction with the atmosphere vaporizes them with a flash of light is called

A

Shooting Stars

102
Q

Meteors that strike Earth

A

Comets

103
Q

When Earth’s intersects that “cloud” we experience a

A

Meteor Shower

104
Q

Any fragment of interplanetary debris that survives evaporation on Earth’s atmosphere

A

Meteorites

105
Q

What is the formation of terrestrial planets?

A

All solid material condensates into planetsimals, which then are accreted onto each other to form more massive bodies (planets)

106
Q

What is the formation of gas giants?

A
  • Collapsed masses can be larger in the outer regions where there is gas and ices in addition to rocks.
  • Planetesimals get massive enough to retain all the hydrogen gas around them.
  • They also heat up a lot in the process! (But not enough to ignite nuclear reactions like the stars)
107
Q

The conservation of angular momentum in the early stages of the solar system helps explain:

A

That all planet’s orbits are approximately on the same plane

108
Q

Where is the asteroid belt located?

A

Between Mars and Jupiter and the Kuiper Belt

109
Q

Enormous ball of extremely hot, largely ionized gas, shinning under its own power

A

The Sun

110
Q

What does ionized mean?

A
  • Many atoms have been stripped from one or more electrons
  • This produces a ‘soup’ of free electrons and positively charged ions
111
Q

Electrically charged soup

A

Plasma

112
Q

What information do we get from the H-R diagram?

A
  • Luminosity
  • Temperature (special type)
  • Size (radius)
  • Mass (only MS stars!) (ms = main sequence)
113
Q

What are the special properties of the main sequence (MS)?

A
  • Stars in the MS are fusing 4 protons into 1 Helium nucleus
  • Stars spend 90% of their lives during H (protons) into He
  • Stars spend 90% of their lives in the MS
  • Most of the stars, ~90%, are in the MS
114
Q

Why are they more luminous?

A
  • More massive means stronger gravity.
  • More gravity compresses more their centers.
  • More compressed cores means hotter temperatures.
  • High temperature implies higher efficiency fusing protons (H) into He.
  • More fusion reactions means more energy.
  • More energy means more luminosity.
  • More luminous because they are more massive!
115
Q

Where are stars formed?

A

Formed in regions of massive reservoirs of gas and dust

116
Q

What are the reservoirs that stars are formed in?

A

Molecular clouds

117
Q

Have molecules in them, so they have cool temperatures

A

Molecular clouds

118
Q

What is the process of star formation?

A
  • Dense cores are formed inside the molecular clouds because of gravity overcoming pressure
  • These dense cores rapidly collapse due to gravity and the density increases even more
  • A protostar is born
119
Q

Once the protostar is born, what’s next?

A
  • The protostar already has a mass (M), a luminosity (L), and a temperature (T).
  • It’s different from a star because it isn’t transforming H into He just yet (the temperature is not high enough in the core).
  • Because it’s an object with M, L, and T, we can place it in an
  • “H-R diagram of protostars”. (We call this kind of diagram ‘evolutionary tracks’.)

Exploring the Universe (1 decks)

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