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S2 Physics > Space > Flashcards

Space Flashcards

(106 cards)

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1
Q

What is the Sun?

A

Star at centre of our solar system.

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2
Q

What is the Sun surrounded by?

A

Planets, moons, asteroids and comets.

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3
Q

What are the planets that orbit the Sun in order of closest to the Sun?

A

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune

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4
Q

What are moons?

A

Natural objects that orbit planet.

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5
Q

How many moons does Mars have?

A

2

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6
Q

What are asteroids?

A

Minor planets or rocks that orbit Sun.

Vary in size from few metres to several hundred km across.

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7
Q

What are comets?

A

Objects that orbit Sun made from dust and ice.

Approx 1 to 30km in diameter.

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8
Q

What is special about the orbits of comets?

A

Very elongated.

Sometimes path very close to Sun and at other times found at outer reaches of solar system.

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9
Q

When and who proposed the idea that any two masses in the universe attract each other?

A

1665, Isaac Newton.

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10
Q

What is the forces between two masses in the universe called?

A

Force of gravity.

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11
Q

What causes the size of the gravitational force to increase between two masses in the universe?

A

Mass of objects.

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12
Q

What causes the size of the gravitational force to decrease between two masses in the universe?

A

Further they are apart.

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13
Q

Where is the direction of the gravitational force between two masses in the universe?

A

Between centres of mass of two objects.

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14
Q

What is the gravitational force on each kilogram at the surface of the earth?

A

About 10N.

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15
Q

What is the name of the force which causes any objects, including planets, to move in a circular path?

A

Centripetal force.

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16
Q

What is the equation for a centripetal force?

A

F = m v2^ / r

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17
Q

What are the quantities involved in the equation F = m v2^ / r ?

A

F = centripetal force, Newtons / N
m = mass of object, kilograms / kg
v = velocity of object, m/s
r = radius of object, meters / m

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18
Q

What causes the centripetal force to increase?

A

Mass of object increases.
Speed of object increases.
Radius of object decreases.

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19
Q

What are geostationary satellites?

A

Satellites always 36,000km above equator and orbit in 1 day so each one always above same point on equator.

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20
Q

What are some examples of geostationary satellites?

A

Communication satellites for to, radio and internet.

Satellites for satellite navigation systems.

Weather monitoring satellites.

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21
Q

What are polar satellites?

A

Satellites which travel in polar orbits over north and south poles of Earth, continually passing over new areas of Earth.

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22
Q

What are polar satellites used for?

A

Mapping earth resources.
Mapping (Google Earth).
Spying (Government or Military monitoring and surveillance).
Monitoring of environment.

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23
Q

What is the diameter of Mercury compared with Earth?

A

0.4

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24
Q

What is the diameter of Venus compared with Earth?

A

0.9

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25
What is the diameter of Earth compared with Earth?
1.0
26
What is the diameter of Mars compared with Earth?
0.5
27
What is the diameter of Jupiter compared with Earth?
11.2
28
What is the diameter of Saturn compared with Earth?
9.4
29
What is the diameter of Uranus compared with Earth?
4.1
30
What is the diameter of Neptune compared with Earth?
3.9
31
What is the diameter of Pluto compared with Earth?
0.4
32
What is the average distance of Mercury from the Sun compared with Earth?
0.4
33
What is the diameter of Venus compared with Earth?
0.7
34
What is the diameter of Earth compared with Earth?
1.0
35
What is the diameter of Mars compared with Earth?
1.5
36
What is the diameter of Jupiter compared with Earth?
5.2
37
What is the diameter of Saturn compared with Earth?
9.5
38
What is the diameter of Uranus compared with Earth?
19.1
39
What is the diameter of Neptune compared with Earth?
30.1
40
What is the diameter of Neptune compared with Earth?
39.4
41
What is the time to orbit the Sun of Mercury compared with Earth?
0.2
42
What is the time to orbit the Sun of Venus compared with Earth?
0.6
43
What is the time to orbit the Sun of Earth compared with Earth?
1.0
44
What is the time to orbit the Sun of Mars compared with Earth?
1.9
45
What is the time to orbit the Sun of Jupiter compared with Earth?
12.0
46
What is the time to orbit the Sun of Saturn compared with Earth?
29.0
47
What is the time to orbit the Sun of Uranus compared with Earth?
84.0
48
What is the time to orbit the Sun of Neptune compared with Earth?
165.0
49
What is the time to orbit the Sun of Neptune compared with Earth?
248.0
50
How many moons does Mercury have?
0
51
How many moons does Venus have?
0
52
How many moons does Earth have?
1
53
How many moons does Mars have?
2
54
How many moons does Jupiter have?
14
55
How many moons does Saturn have?
24
56
How many moons does Uranus have?
15
57
How many moons does Neptune have?
3
58
How many moons does Pluto have?
1
59
What was the first accepted model of the solar system?
Geocentric Model
60
What does the Geocentric Model believe?
Earth at centre of solar system.
61
What is the currently accepted model of the solar system?
Heliocentric model.
62
What does the heliocentric model believe?
Sun at centre of solar system.
63
Who and when proposed the geocentric model?
Pythagoras, 500BC.
64
What did the geocentric model not explain?
Strange loops planets such as Jupiter made as crossed sky. Phases of moon. Why sometimes Venus was brighter than Mars and vice versa.
65
Who, when and how explained the loops of planets?
Ptolemy in AD120 with construction of epicycles.
66
Who and when proposed the heliocentric model?
Copernicus in 16th century.
67
Who opposed tue heliocentric model?
Catholic Church
68
How are stars formed?
1. Gravitational attraction pulls together hydrogen gas and dust called nebulae. 2. As clouds become more and more dense start to spiral inwards. 3. Temp rises enormously until temp reach 15 million K. 4. Nuclear fusion reactions start and start is born.
69
What two gases are the main constituents of stars?
Hydrogen and helium.
70
How do astronomers know stars are made of hydrogen and helium gas?
By looking at spectrum of star.
71
What evidence suggests that the planets in our solar system were from the same large rotating nebula as our Sun?
1. All or it Sun on same plane. 2. All made up of same elements.
72
What else is produced by nuclear fusion in a star?
Heavy helium nuclei.
73
What happens during nuclear fusion in stars?
Light hydrogen nuclei fuse together to form heavier helium nuclei under very high temp and pressure.
74
What is our galaxy called?
Milky Way
75
What evidence is there that the Universe is expanding?
Light from all other galaxies around is is shifted to red end of spectrum of Doppler Effect.
76
What is observed the further away a galaxy is from Earth?
Greater red shift is so further so further away galaxy is, faster it is moving away from Earth.
77
When did the Big Bang occur?
12-15 million years ago.
78
What further evidence is there for the Big Bang Theory?
Cosmic microwave background radiation which whole universe emits which thought to be distant echo of Big Bang.
79
Who and when discovered cosmic microwave background radiation?
Penzias and Wilson in 1965.
80
When was the first satellite launched into Earth’s orbit?
October 1957.
81
When did the first person travel in a spacecraft sourness the Earth?
April 1965.
82
What are the problems facing further exploration into space?
Logistics, risks and cost.
83
What telescope has allowed us to find out that some other stars have planets which orbit around them?
Hubble Space Telescope
84
What is the measurement used to measure the length between space objects?
Light-years
85
What is a light-year?
Distance light travels in a year.
86
What is the speed of light?
300,000,000m/s (3.0x10^8m/s)
87
What is the length of a year?
365 days = 3.15x10^7 seconds
88
How long is one light-year?
9.46x10^15m
89
What is a star?
Hot ball of hydrogen and helium gas in which nuclear fusion results in production and emission or electromagnetic radiation.
90
How can stars vary?
Age Size Mass Surface temperature Colour Brightness
91
What does the colour and brightness of a star depend on?
Surface temp which in turn increases with mass of star.
92
What stars are hotter and brighter?
Blue or white stars.
93
What stars are less bright and hot?
Yellow or red stars.
94
What causes a blue or white star to form during the formation of a star?
If ‘young star’ has very large mass.
95
What causes a yellow or red star to form during the formation of a star?
If ‘young star’ has smaller mass.
96
What stars are more common?
Yellow or red stars.
97
What type of star is our Sun at present?
Yellow dwarf star (average mass main sequence star).
98
Why do main sequence stars, such as our Sun, remain stable for many billions of years?
Very strong forces of gravity pulling it together balanced by opposing forces trying to make it expand due to its extremely high temperature.
99
How long does a main sequence star in a stable state last for?
About 10,000 million years during which hydrogen in core changed to helium.
100
What is a ‘young star’ called?
Protostar
101
What are the possible life cycles of a star?
Protostar > Average mass main sequence star > Red giant star > White dwarf > Black dwarf Or Protostar > Massive main sequence star > Red super giant star > Supernova > Neutron star/Black hole
102
What is a supernova?
When red supergiant explodes in which outer layers of star are ejected.
103
What is a black hole?
When remnants of supernova leaves enough matter behind, may contract under own gravity to become extremely dense, with such strong gravitational field that nothing can escape it, including electromagnetic radiation.
104
What is special about black holes?
Cannot be seen.
105
How can black holes be observed?
Effects on gases from neighbouring stars can be observed. E.g. X-rays are emitted when these gases spiral into black hole.
106
How does the Sun’s gravity affect the motion of planets?
Causes planets to orbit around Sun.

S2 Physics (4 decks)

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