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Visions of the Universe > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What is the North Celestial Pole?

A

the point directly over Earth’s north pole

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2
Q

What is the South Celestial Pole?

A

the point directly over Earth’s south pole

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3
Q

What is the Celestial Equator?

A

The projection into space of the earth’s equator; an imaginary circle equidistant from the celestial poles

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4
Q

What is the Ecliptic?

A

the path the sun appears to travel in the sky

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5
Q

What is the Zenith?

A

the point directly over your head

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6
Q

What is the Meridian?

A

an imaginary line across the celestial sphere that extends from north to south and passes through the zenith

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7
Q

What is the Horizon?

A

the line between the earth and sky

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8
Q

What determines what stars you can see?

A

the latitude

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9
Q

What are circumpolar stars?

A

Stars that never set below the horizon, meaning you can always see them

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10
Q

What causes the seasons?

A

the tilt in the earth’s axis causes hemispheres to receive more direct sunlight when they are tilted towards the sun

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11
Q

Which way do the phases of the moon start from?

A

the right, which is a waxing crescent

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12
Q

When does a lunar eclipse occur?

A

When the earth is between the moon and the sun, with the earth blocking the sunlight

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13
Q

When does a solar eclipse occur?

A

When the moon is between the earth and sun, with the moon blocking the sunlight

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14
Q

Why don’t eclipses happen every month?

A

Because the moon’s orbit is not linear, it varies up and down

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15
Q

What is retrograde motion?

A

Planets whose orbits are outside of Earth’s orbit appear to move backwards in the sky during a portion of their orbit

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16
Q

What is the Geocentric Model?

A

earth as the center of the universe

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17
Q

What is the Ptolemaic Model?

A

earth as the center, with the planets traveling in small circles while orbiting the earth, in order to describe retrograde motion

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18
Q

What is the Heliocentric Model?

A

Sun at the center of the universe, with circular orbits.

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19
Q

Was the Heliocentric Model any better than the Ptolemaic Model?

A

No, the circular orbits did not make sense and proved to be just as inaccurate

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20
Q

What was Keplers first law?

A

elliptical orbits

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21
Q

What was Kepler’s second law?

A

equal area in equal time. Meaning the closer to the sun you are, the faster you go

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22
Q

What was Kepler’s third law?

A

p^2 = a^3. Meaning the further away you are, the longer it takes to orbit

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23
Q

What is the difference between a hypothesis and a theory?

A

A hypothesis is an educated guess that is tested. A theory is a scientific model that withstands repeated and varied testing. It is not a guess as it describes a law of nature

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24
Q

What is speed?

A

How far an object travels in a given amount of time

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25
Q

What is velocity?

A

the speed and direction of an object

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26
Q

What is acceleration?

A

the change in velocity

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27
Q

Why don’t all objects fall at 9.81 m/s^2?

A

because air resistance slows down objects

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28
Q

What is momentum?

A

the mass * velocity of an object

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29
Q

What is mass? Is it the same everywhere?

A

The amount of matter something is made of. It is the same everywhere

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30
Q

What is weight? Is it the same everywhere?

A

The force that a scale measures when you place an object on it. It varies depending on where you are in the universe

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31
Q

What does Newton’s 1st Law say?

A

if the net force on an object in zero, it will move with a constant velocity

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32
Q

What does Newton’s 2nd Law say?

A

F = MA

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33
Q

What does Newton’s 3rd Law say?

A

For any force there is an equal and opposite reaction force

34
Q

Is angular momentum always conserved? What does it mean?

A

Angular momentum is always conserved. It means that if a velocity increases, the radius must decrease. (mvr)

35
Q

Is total energy always conserved?

A

Total energy is always conserved, however energy can be converted from one kind to another

36
Q

What is the Universal Law of Gravitation?

A

Every mass attracts every other mass through the force of gravity. The further away an object is, the gravity decreases. For example if the moon were twice as far away, the gravity is 4x less.

37
Q

Which of the following correctly lists our “cosmic address” from small to large?

A

Earth, solar system, Milky Way, Local Group, Local Supercluster, universe

38
Q

When we say the universe is expanding, we mean that?

A

The average distance between galaxies is growing with time

39
Q

Could we see a galaxy that is 20 billion light-years away?

A

No, because it would be beyond the bounds of our observable universe

40
Q

A star is 425 light years away. If it explodes tonight?

A

We won’t know until 425 years from now

41
Q

If we represent the solar system on a scale that allows us to walk from the Sun to Pluto in a few minutes, then:

A

the planets would all be marble size or smaller and the nearest stars would be thousands of miles away

42
Q

The age of our solar system is about:

A

1/3 the age of the universe

43
Q

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude what?

A

The universe is expanding

44
Q

An AU is?

A

The Earth’s average distance from the Sun

45
Q

Two stars that are in the same constellation are..?

A

they may actually be very far away from each other

46
Q

The North Celestial Pole is 35 degrees above your northern horizon. This tells you what?

A

you are at latitude 35 degrees N

47
Q

Beijing and Philly have about the same latitude but very different longitudes. Therefore, tonight’s night sky in these two places will?

A

Look about the same

48
Q

If the Sun rises precisely due east:

A

it must be the day of either the spring or fall equinox

49
Q

A week after full moon, the Moon’s phase is?

A

third quarter

50
Q

When we see Saturn going through a period of apparent retrograde motion, it means?

A

Earth is passing Saturn in its orbit, with both planets on the same side of the Sun.

51
Q

In the Greek geocentric model, the retrograde motion of a planet occurs when?

A

The planet actually goes backward in its orbit around Earth.

52
Q

Which of the following was not a major advantage of Copernicus’s Sun-centered model over the Ptolemaic model?

A

It did not make any better predictions

53
Q

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler’s second law:

A

Earth travels faster in its orbit around the Sun in January than in July

54
Q

When we say that a planet has a highly eccentric orbit, we mean that:

A

in some parts of its orbit it is much closer to the sun than in other parts

55
Q

According to Kepler’s third law:

A

Planets closer to the sun orbit at a faster speed

56
Q

Tycho Brahe’s contribution to astronomy included:

A

Collecting data that enabled Kepler to discover the laws of planetary motion

57
Q

Galileo’s contribution to astronomy included:

A

Making observations and conducting experiments that dispelled scientific objections to the Sun centered model

58
Q

Which of the following is not true about a scientific theory?

A

A theory is essentially an educated guess

59
Q

When Einstein’s theory of gravity gained acceptance, it demonstrated that Newton’s theory had been what?

A

incomplete

60
Q

If you visited another planet, how would your weight and mass be affected?

A

Your mass would be the same as on Earth, but your weight would be different

61
Q

Consider the statement “There’s no gravity in space”. This statement is:

A

Completely false

62
Q

If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be”

A

1/4 as strong

63
Q

Why is a sunflower yellow?

A

It reflects yellow light?

64
Q

Blue light has higher frequency than red light. Thus, blue light has:

A

Higher energy and shorter wavelength than red light

65
Q

Compared to an atom as a whole, an atomic nucleus is:

A

very tiny but has most of the mass

66
Q

Some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are called what?

A

isotopes

67
Q

The set of spectral lines that we can see in a star’s spectrum depends on the star’s what?

A

chemical composition

68
Q

A star whose spectrum peaks in the infrared is what?

A

cooler than our Sun

69
Q

A spectral line that appears at a wavelength of 321nm in the lab appears at a wavelength of 328nm in the spectrum of a distant object. We say that the object’s spectrum is what?

A

redshifted

70
Q

The hubble Space Telescope obtains higher-resolution images than most ground based telescopes because?

A

it is above Earth’s atmosphere

71
Q

What is the relationship between photons, energy and frequency?

A

Energy increases as frequency increases

72
Q

From longest wavelength to shortest wavelength what is the order of the electromagnetic spectrum?

A

radio, micro, infrared, visible light, UV, x-ray, gamma

73
Q

What are isotopes?

A

Elements with different number of neutrons

74
Q

What are atoms made of?

A

electrons, protons, and neutrons

75
Q

What is emission?

A

something that generates light (sun, light bulb)

76
Q

What is transmission?

A

light can go through objects such as glass

77
Q

What are emission lines?

A

dark with spots lit up

78
Q

What are absorption lines?

A

full spectrum with black lines

79
Q

Based on the peak wavelength, what can we tell about the star?

A

its temperature

80
Q

How does moving along the spectrum affected the temperature of the object?

A

cooler objects shift towards UV, warmer shifts towards infrared

81
Q

What is a redshift?

A

moving away from us (right)

82
Q

What is a blueshift?

A

moving towards us (left)

Visions of the Universe (4 decks)

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