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intro to the universe > exam 2 > Flashcards

exam 2 Flashcards

1
Q

Which 2 planets are our closest neighbor planets?

A

Venus and Mars

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2
Q

What is the atmosphere of Venus like?

A

Very Thick
- pressure and temperature are very high (850°)
- chemical composition is poisonous to humans

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3
Q

What is the atmosphere of Mars like?

A

Very Thin
- pressure at its surface is less than 1% that of Earth
- temperatures can range from 70° to -225°

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4
Q

Which planet (Venus or Mars) has been easier to research and why?

A

Mars
- The temperature conditions allow robotic missions to land and survive for long periods of time

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5
Q

Why is Venus the brightest object in the sky?

A

its closeness to the Sun and Earth
- highly reflective layer of clouds

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6
Q

Why can we not view the face of Venus?

A

it is covered by dense clouds making it impossible to directly observe its surface

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7
Q

How are Radio Waves emitted / how do they work?

A

emitted by the radar toward the planet and they then penetrate the clouds and reflect on the surface
- their reflection gives information about the altitude and roughness of the surface

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8
Q

Which planet approaches Earth closer than any other planet?

A

Venus

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9
Q

What is the surface of Mars like?

A

dry and cold, bright polar ice caps, heavily cratered highland terrain, volcanoes

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10
Q

How have scientists determined the rotational period of Mars?

A

by watching the motion of permanent surface markings over a long period of time

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11
Q

How long is 1 day on Mars? (rotation period)

A

24 hrs and 37 mins

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12
Q

What is the rotational axis of Mars? (tilt)

A

Mars has a tilt of about 25° (similar to Earth’s)
- similar seasons

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13
Q

How have scientists determined the rotational period of Venus, being that the surface isn’t visible?

A

by bouncing radar signals off the planet

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14
Q
  • How long is 1 day on Venus? (rotation period)
  • How long is 1 year on Venus?
    (how long it takes Venus to orbit the Sun)
A

(1 day) 243 days

(1 year) 225 days

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15
Q

Which way do planets normally rotate?

A

West to East
- counterclockwise

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16
Q

Which way does Venus rotate on its axis?

A

East to West
- clockwise
- “retrograde” / backwards

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17
Q

Describe the surface of Venus

A

lowland lava plains, many geologic features (volcanos, mountains, and large impact craters)
- basalts

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18
Q

What is the 1st and 2nd most abundant gases on Venus and Mars?

A

carbon dioxide
- nitrogen

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19
Q

What makes Venus so hot?

A

The greenhouse effect

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20
Q

Greenhouse Effect

A

greenhouse gases trap heat from the sun, preventing it from escaping back into space and thus warming the planet’s surface

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21
Q

Why does the Greenhouse Effect affect Venus more than Earth?

A

Venus has around 1 million times more carbon dioxide than Earth (CO2)

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22
Q

Describe the evidence for the presence of water in the past history of Mars

A

The climate on Mars used to be warmer with a thicker atmosphere (which would allow water to be liquid on the surface)
- Runoff Channels, Outflow Channels, Smaller Gullies

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23
Q

Runoff Channels

A

small twisting channels that look like have been formed from runoff of ancient storms

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24
Q

Outflow Channels

A

large, long, and wide channels that are carved by massive floods of water

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25
Q

Smaller Gullies

A

located on steep slopes
- very young channels like look like dark streaks

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26
Q

What does Mars not have?

A

Ozone Layer

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27
Q

Why did Mars lose atmospheric gases more easily and quickly than other planets?

A
  • Low gravity
  • Small planet
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28
Q

What are the 4 giant (Jovian) planets in our solar system?

A

Jupiter, Saturn, Uranus, and Neptune
- they hold most of the mass in our system

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29
Q

What 3 materials are giant planets made of?

A

Gases (hydrogen and helium), Rocks, Ice

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30
Q

The chemistry for all 4 giant planet atmospheres is dominated by _____

A

Hydrogen

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31
Q

The giant planets are very far from the Sun
- (True/False)

A

True

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32
Q

Which planet has the shortest day?

A

Jupiter (10hrs)

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33
Q

Why do Earth and Mars have seasons?

A

Because their “spin axes” are tilted relative to the orbital plane of the solar system

34
Q

What is the spin axis tilt of Uranus?

A

98°
- orbits on its side
- creates dramatic seasons

35
Q

Which of the 4 giant planets has no seasons?

A

Jupiter

36
Q

What are the interiors of Jupiter and Saturn primarily composed of?

A

hydrogen and helium

37
Q

What does “Saturn is still differentiating” mean?

A

Letting lighter material rise and heavier material fall

38
Q

Which giant planet has the largest internal energy source?

A

Jupiter

39
Q

Uranus and Neptune have lower energy sources than Jupiter and Saturn
- (True/False)

A

True

40
Q

What are magnetic fields generated by?

A

Electric currents in the planet’s rapidly spinning interior

41
Q

Define magnetospheres

A

regions around the planet where the planet’s own magnetic field dominates over the general interplanetary magnetic field
- largest features

42
Q

Jovian (giant) planets have solid surfaces
- (True/False)

A

False

43
Q

The primary clouds seen around Jovian (giant) planets are composed of what?

A

frozen ammonia crystals

44
Q

Within the tropospheres of Jovian (giant) planets, the temperature and pressure both increase with depth
- (True/False)

A

True

45
Q

What are Uranus and Neptune’s upper clouds composed of?

A

methane

46
Q

How do we track wind speeds and the circulation of atmospheres on Jovian planets?

A

by observing changing cloud patterns

47
Q

Giant planets spin faster than terrestrial planets
- (True/False)

A

True

48
Q

Deep convection currents of rising hot air and falling cooler air circulate throughout the atmospheres of Jovian planets in a vertical direction
- (True/False)

A

True

49
Q

What is convection?

A

A process in which liquids, heated from underneath, have regions where hot material rises and cooler material descends

50
Q

Giant Molecular Clouds

A

birthplace of stars
- a massive, dense cloud of gas and dust in space

51
Q

T Tauri Stars

A

end of the stars formation phase (less than 10 million years old)
- about to fuse hydrogen in their core
- circumstellar disks / stellar winds

52
Q

Herbig-Haro (HH) Object

A

high velocity jets slamming in
- newborn star

53
Q

Cloud clumps

A

large substructures of molecular clouds that occur before star clusters

54
Q

Cloud core

A

the densest parts of molecular clouds where stars form

55
Q

The brightness of a star indicates…

A

the relative concentration of dust
- more dust means more radiation

56
Q

Define exoplanet

A

a planet outside our solar system

57
Q

Planets and their host star

A

both the planet and the star revolve around their common center of mass

58
Q

Doppler Effect

A

detects a slight “wobble” in a star’s motion caused by the gravitational pull of a planet orbiting it
- allows us to find the minimum mass of a planet
- provided the first concrete evidence that the universe is expanding

59
Q

Define radial velocity

A

motion towards or away from us

60
Q

Explain how the environment of a molecular cloud enables the formation of stars.

A

A molecular cloud provides a dense, cold environment where gravity can overcome internal pressure, causing the gas and dust within the cloud to collapse and form protostars

61
Q

What planets emit more infrared light because they have more internal energy?

A

young giant planets

62
Q

What is responsible for the discovery of most exoplanets?

A

The Kepler Telescope

63
Q

The most common planet size are those called…

A

“Super-Earths” & “Mini-Neptunes”

64
Q

Define “habitable zone”

A

the distance from the star where we calculate the surface temperatures would be consistent with liquid water

65
Q

Luminosity

A

the total amount of energy at all wavelengths that it emits per second
- total energy output

66
Q

Brightness

A

the amount of a star’s energy that reaches a given area

67
Q

Stars emit the same amount of energy in every direction in space
- (True/False)

A

True

68
Q

Define photometry

A

the process of measuring the apparent brightness of stars

69
Q

The brightest stars are usually referred to as what?

A

first-magnitude stars

70
Q

Define the magnitude scale

A

Used to measure the brightness of a star
- the brightest objects have the SMALLEST number and the faintest objects have the LARGEST numbers
- backwards scale

71
Q

Why are stars different colors?

A

Because they do not all have identical temperatures

72
Q

Blue colors

A

additional radiation in the ultraviolet
- dominate the visible light output of very hot stars

73
Q

Red colors

A

more radiation coming off in the infrared
- cool stars

74
Q

Color does not depend on the distance of an object (color would not change)
- (True/False)

A

True

75
Q

What is the primary reason why stellar spectra look different?

A

the stars have different temps

76
Q

Spectral classes are a measure of a star’s ____?

A

surface temp.

77
Q

There are 7 spectral classes from _____ to ______?

A

Hottest to coldest
- O. B, A, F, G, K, and M

78
Q

Spectra classes L, T, and Y

A

brown dwarfs
- objects cooler than M9 type stars

79
Q

Brown dwarfs

A

object that is between a planet and a star

80
Q

What is the difference between a Low-Mass Brown Dwarf and a High-Mass Planet?

A

Deuterium Fusion
- Brown dwarfs can’t sustain regular hydrogen fusion, but they are capable of deuterium fusion

intro to the universe (3 decks)

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