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8th Grade Science > Astronomy > Flashcards

Flashcards in Astronomy Deck (137):
0

What is a Solar System?

planets, moons, & non-stellar objects that orbit the sun or central star

1

What is a Planet?

an astronomical object that orbits a star & is massive enough for its own gravitational pull

2

What is a Moon?

a natural satellite of a planet

3

What is a Star?

a self-luminous gaseous sphere

4

What is an Orbit?

a path followed by a star, planet, or satellite around a more massive body

5

What is Rotation?

turning around an axis, or to turn in a circle

6

What is Revolution?

the orbiting of one body in space around another

7

What is an Eclipse?

the effect caused by one body casting a shadow on another

8

What is a Solar Eclipse?

when the moon passes between the sun & earth, casting a shadow on earth

9

What is a Lunar Eclipse?

when earth passes between the sun & moon, casting a shadow on the moon

10

What is an Umbra?

the dark, central zone created by an eclipse (region where all direct sunlight is blocked)

11

What is a Penumbra?

the outer & lighter part of the shadow created by an eclipse (region where only part of the sun's rays are blocked)

12

What are Phases?

the different sizes of the illuminated portion of a planet or moon due to its changing position

13

What is a Wax?

an increase in the phase of a moon or planet

14

What is a Wane?

a decrease in the phase of a moon or planet

15

What are Gas Giants?

the largest planets in the solar system (our outer planets, like Jupiter & Saturn), made largely of dense gaseous atmosphere

16

What are Terrestrials?

the smallest planets in the solar system (our inner planets), made primarily of rock

17

What is an Asteroid?

a small, rocky body that orbits the sun (aka a planetoid)

18

What is a Comet?

a body of ice & dust in orbit about the sun that develops a tail of ions & dust as it approaches the sun

19

What is a Meteroid?

a very small, rocky body that orbits the sun. most probaby come from asteroids

20

What is a Meteor?

a streak of light caused when a meteroid burns up in the atmosphere before it reaches the ground

21

What is a Meteorite?

a meteroid that reaches the earth's surface without burning up completely

22

What is the Universe?

it consists of all existance, including all matter

23

What is a Galaxy?

a gravationally bound system, containing stars, gas, & dust

24

What is a Solar System?

it consists of the Sun & its planetary systems (planets, moons, non-stellar objects [comets, meteors, etc.] )

25

What is a Planet?

an astronomical object, orbiting a star or stellar remnant, that is massive enough to be rounded by its own gravity

26

What is a Spiral Galaxy?

• disk shaped
• curving arms

27

What is a Barred Spiral Galaxy?

a spiral galaxy with a central bar-shaped structure composed of stars

28

What is an Elliptical Galaxy?

• approximately ellipsoidal shape
• smooth, nearly featureless bright profile

29

What is an Irregular Galaxy?

• no distinct shape
• could have been a spiral or elliptical galaxy that has been distorted

30

What did Ptolemy believe? (and what was his year?)

Earth is the center of the universe; the sun & planets revolve around the earth.
140 A.D.

31

What did Capernicus believe? (and what was his year?)

Sun is the center of the universe; planets revolve around the sun.
1543

32

What did Brahe believe?

Other planets revolve around the sun; sun & moon revolve around the earth.

33

What did Kepler believe? (and what was his year?)

All planets revolve around the sun in elliptical orbits; the sun isn't the center of the orbits.
1609

34

What did Galilei do? (and what was his year?)

Used a telescope to discover: 1) Jupiter's 4 moons, 2) craters & mountains on our moon, 3) sunspots on the sun, and 4) the phases of Venus.
1609

35

What did Newton do? (and what was his year?)

Explained that the force that holds us to earth is gravity; the same force keeps objects in orbit.
1687

36

What did Herschel do? (and what was his year?)

Discovered Uranus & saw small, fuzzy patches of stars.
1781

37

What did Hubble do? (and what was his year?)

Discovered: 1) other galaxies through photography, 2) that small patchy stars are galaxies, and 3) that the Milky Way isn't the entire universe.
1923

38

The moon travels...

around the Earth

39

What makes the moon appear as if it is changing shape in the sky?

the revolution of the moon around the earth

40

What is the phase of the moon?

the changing shape of the bright part of the moon that we see

41

What causes the different phases of the moon?

the phases depend on the moon's position in relation to the sun & earth

42

What causes part of the moon to be lit up?

it is illuminated because it reflects light from the sun

43

How many different phases of the moon are there?

8 phases

44

How many days does our moon take to completely cycle through all 8 phases?

29.5 days

45

When the bright part of the moon is getting bigger, the moon is...

waxing

46

When the bright part of the moon is getting smaller, the moon is...

waning

47

When the moon is more than half-lit, it is called a...

gibbous moon

48

When the moon is less than half-lit, it is called a...

crescent moon

49

Why are you able to see the moon at night & at times during the day?

the moon rises & sets just like the sun does

50

What is another name for a new moon?

a dark moon

51

When is the best time to see a waxing crescent moon?

the 2nd & 3rd days after new moon

52

What is another name for a first quarter moon?

half moon

53

The moon travels around the earth in an...

orbit

54

What is a lunar month?

the time it takes the moon to pass through a complete cycle of its phases

55

The planets travel in nearly circular paths called...

orbits

56

Everything is held together & all movement in the solar system os governed by the pull of the sun's...

gravity

57

Gravity is a ___ that attracts objects to each other.

force

58

Earth's gravity is strong enough to keep the ___ orbiting around us.

moon

59

Why do night & day occur?

because of earth's rotation on its axis

60

The earth revolves around the sun in an ___ orbit.

elliptical

61

It takes earth ___ days to orbit the sun. This is called a ___.

365.25 days; year

62

The earth completes one full ___ on its ___ in 23 hours & 56 minutes. This is an earth ___.

rotation; axis; day

63

The earth rotates in a ___ direction.

counterclockwise

64

The sun always appears to rise in the ___ & set in the ___.

east; west

65

Where are most asteroids located?

between Mars & Jupiter, in a region called an asteroid belt

66

Earth's orbit is its ___ around the sun.

revolution

67

The moon is Earth's ___ moon, and is one of over ___ moons in our sola system.

only; 96

68

About how far is the moon from Earth?

about 240,000 miles from Earth

69

How big is the moon's diameter, and what is its size and gravity strength compared to Earth?

2,155 miles in diameter; about 1/4 of Earth's size; 1/6 of Earth's gravity

70

What is the moon's extreme daytime & nighttime temperatures?

Daytime = 265°F
Nighttime = -310°F

71

How was the moon formed?

About 4.6 billion years ago, a large body collided with Earth. At the time, Earth was mainly molten lava. Debris from the collision collected & orbited around Earth. Eventually, the debris pulled together due to gravity & formed the moon. The moon cooled & formed cracks where lava would flow & form laza basins.

72

What are the Highlands on the moon?

mountains up to 25,000 ft tall; the bright areas of the moon b/c light rocks reflect the sunlight

73

What does Maria mean?

it is Latin for "seas"

74

What is the Maria on the moon?

the darker areas of the moon; depressions created by giant meteorites that filled with lava during periods of volcanic activity

75

Where did Apollo 11 land in when it got on the moon?

it landed in a maria

76

Why does the moon have no protection from meteorites?

it has no atmosphere

77

How big are some craters on the moon?

up to 1,553 miles across

78

How are the craters formed?

most are formed by meteorite impact on the moon; some are formed by volcanic action inside the moon

79

What are some craters surrounded by?

bright streaks called rays

80

What are rays made of?

crushed rock thrown out of the crater at the time of impact

81

Who first saw the far side of the moon & when?

first seen by Luna 3 Russian space probe in 1959

82

How are the surface features of the far side of the moon different from the near side?

• more craters
• very few maria
• thicker crust

83

The moon rises & sets ___ minutes later each day.

50 minutes

84

The moon rotates on its axis every ___ days.

27 days

85

Why does the same side of the moon always face Earth?

b/c moon rotates on axis the same amount of time it takes to orbit Earth ( ~ 27.3 Earth days) --> SYNCHRONOUS ROTATION

86

What is a blue moon?

the 2nd full moon in 1 month - it is very rare (hence the saying "once in a blue moon")

87

What is a harvest moon?

the full moon closest to the autumnal equinox

88

8 Phases of the Moon in Order:

1. New Moon (day 0)
2. Waxing Crescent (day 4)
3. First Quarter (day 7)
4. Waxing Gibbous (day 10)
5. Full Moon (day 14)
6. Waning Gibbous (day 18)
7. Third Quarter (day 22)
8. Waning Crescent (day 26)
1. New Moon (day 29)

89

What is the difference between a solar eclipse and a lunar eclipse?

A solar eclipse is when the moon is between the sun and the earth, and a lunar eclipse is when the earth is between the sun and the moon.

90

Which eclipse (solar or lunar) can you not look directly at? Why?

You can't look at a solar eclipse directly because you will get eye damage and maybe even go blind.

91

If you are in the umbra during an eclipse, you will see a ___ eclipse.

total

92

If you are in the penumbra during an eclipse, you will see a ___ eclipse.

partial

93

Which eclipse's shadow is bigger: the shadow that falls on the earth during a solar eclipse or the shadow that falls on the moon during a lunar eclipse?

The shadow that falls on the moon during a lunar eclipse is bigger because it is the earth's shadow, which is bigger than the moon's shadow, which would fall on the earth during a solar eclipse.

94

Are you able to see a solar eclipse everywhere on earth?

No, because only people in the umbra and penumbra can see the solar eclipse. Umbra - see total eclipse; Penumbra - see partial eclipse

95

Are you able to see a lunar eclipse everywhere on earth?

No, because only people on the half of the earth in which it is nighttime can see a lunar eclipse. This is because the lunar eclipse is caused by earth's shadow, & where it is nighttime is where earth's shadow is.

96

During which phase of the moon can you see a solar eclipse?

new moon - because the moon is in front of the sun

97

During which phase of the moon can you see a lunar eclipse?

full moon - because the moon is on the opposite side of the earth as the sun

98

What is the corona?

the outer atmosphere of the sun

99

How long do total and partial solar eclipses last?

Total eclipse lasts for a few minutes. Partial eclipse lasts up to 2 hours.

100

Why does the moon turn red when it is in the umbra during a lunar eclipse?

the color wavelengths from the sun are scattered in earth's atmosphere, except for the red wavelengths, which end up reflected on the moon

101

How long do total and partial lunar eclipses last?

Total eclipse lasts for up to 1 and a half hours. Partial eclipse lasts up to 4 hours.

102

Why don't we see eclipses ever month?

the moon's orbit is tilted about 5 degrees, so the moon may pass above or below the shadow.

103

About how many times a year do solar and lunar eclipses occur?

Solar Eclipses are ~ 2-4 times/year.
Lunar Eclipses are ~ 2 times/year.

104

Can partial or total eclipses seen more often? Why?

Partial eclipses can be seen more often because an umbra shadow is a lot smaller than a penumbra shadow.

105

What are Tides?

tides are daily movements of ocean water that change the level of the ocean's surface

106

What causes tides?

the moon's gravity. the moon pulls water on earth, creating a bulge that moves as the moon orbits

107

How long is a lunar day? Why is it longer than a solar day?

24 hours and 50 minutes; because the earth takes an extra 50 minutes to catch up to the moon

108

How many tides are there in a lunar day?

2 high tides & 2 low tides

109

How often do tides change?

2 high & 2 low tides every 24 hrs 50 mins. time between high tides: 12 hrs 25 mins. time between low tides: 12 hrs 25 mins. time it takes to change from a high tide to low tide: 6 hrs 12.5 mins

110

What are the high tides? How are they caused? Therefore, what are the low tides?

2 bulges of water on earth - one facing the moon (due to moon's gravity) & one on opposite side of moon (due to inertia & earth's rotation pushes the water outward. Therefore, low tide is the water area between the bulges.

111

What is a Spring Tide?

especially strong tides. occur when earth, sun, & moon are alligned so both sun's & moon's gravity contribute to tides - high tides = higher, low tides = lower

112

What are the 2 moon phases in which a Spring Tide occurs?

new moon; full moon

113

What is a Neap Tide?

especially weak tides. occur when sun & moon are perpendicular to each other sun's & moon's gravity cancel each other out - high tides & low tides = more moderate

114

What are the 2 moon phases in which a Neap Tide occurs?

quarter moons: first quarter moon; last quarter moon

115

What are the 4 inner planets (in order from closest to sun to farthest from sun)?

Mercury, Venus, Earth, Mars

116

What are the 4 outer planets (in order from closest to sun to farthest from sun)?

Jupiter, Saturn, Uranus, Neptune

117

What is a comet?

a small body of ice, rock, & cosmic dust loosely packed together

118

What are comets sometimes called? Why?

"dirty snowballs" - due to their composition

119

What happens when comets pass close enough to the sun?

solar radiation heats the water ice & the comet gives off gas & dust that forms a long tail

120

What are the 2 tails comets can have?

an ion tail & a dust tail

121

What are asteroids?

small rocky or metallic objects, most of which orbit the sun

122

What is the range of sizes an asteroid can be?

from a few meters to more than 900 km in diameter

123

What can the shapes of asteroids be?

some asteroids have an irregular shape; larger ones can be shaped like a sphere

124

What are asteroids also called?

minor planets

125

Where do most asteroids orbit the sun?

in a wide region between the orbits of Mars & Jupiter

126

What does this Asteroid Belt do?

it separates the inner & outer planets

127

What is a meteoroid?

a small rocky body orbiting the sun, much smaller than asteroids

128

Where do most meteoroids come from?

asteroids

129

As a meteoroid falls through the atmosphere at high speeds, it...

burns up

130

What is a meteor?

a bright streak of light caused by a meteoroid or comet dust burning up in the atmosphere

131

From the ground, when we see a meteor, we see a streak of light, aka a...

"shooting star"

132

How can meteor showers occur? (2 reasons)

1. when a large number of very small meteors fall
2. when the earth passes through the dusty debris left behind in the orbit of a comet

133

What is a meteorite?

when a meteoroid enters the earth's atmosphere & strikes the ground

134

When does a meteoroid become a meteorite?

when it hits the ground

135

What do the Inner and Outer planets have in common?

they both:
- orbit the sun
- rotate on an axis
- are spherical

136

What are the differences between the Inner and Outer planets? (i = inner; o = outer)

- composition (i=rocky; o=gas giants)
- size (i=smaller; o=larger)
- temperature (i=warmer; o=colder)
- density (i=more dense; o=less dense)
- rings (i=no rings; o=do have rings)
- moons (i=less moons; o=more moons)
- orbits (i=smaller; o=larger)
^- year length (i=shorter; o=longer)
- placement in relation to Asteroid Belt (i=before; o=after)