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Physics > Space Physics > Flashcards

Space Physics Flashcards

1
Q

Earth’s Axis

A

Imaginary line joining North Pole of Earth with South pole of earth and is tilted 23.5 degrees from vertical

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2
Q

Equator

A

The Earth’s rotation axis, imaginary line drawn horizontally around the earth, halfway between North pole and south pole

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3
Q

How does day and night occur?

A

Caused by the earth spinning around its axis, where the side facing the sun presents day, and side facing away presents night.

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4
Q

Earths spin:

A

Around its axis, makes 1 complete turn every 24 hours.
The Earth is spinning anticlockwise

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5
Q

Sunrise:

A

A particular spot on Earth, at the eastern horizon, approximately around 6AM, where the sun is just visible.

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6
Q

Midday:

A

A particular spot on Earth, approximately around 12PM, where the sun appears directly overhead, and the Earth faces a full glare of the Sun.

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7
Q

Sunset

A

A particular spot on Earth, at the western horizon, approximately around 6PM, where the earth moves out of the sun rays, sun appears to slip below the western horizon.

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8
Q

Earths Orbit around sun duration:

A

365 days to complete one orbit around the sun

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9
Q

Why do seasons occur:

A

The tilting of the Earth’s axis and the orbiting of Earth around the sun.

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10
Q

How winter occurs:

A

The earth is tipped away from the sun.
The heat energy from the sun’s ray is more spread out, making it colder.
This particular hemisphere receives fewer hours of direct sunlight

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11
Q

How summer occurs:

A

The earth is tipped towards from the sun.
The heat energy from the sun’s ray is less spread out, making it hotter.
This particular hemisphere receives longer hours of direct sunlight

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12
Q

Which place on earth does not experience seasons because the sun’s ray always hits them at the same angle?

A

The Equator

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13
Q

In which areas are seasonal changes much more extreme?

A

Top of north pole and bottom of south pole;

Seasonal differences are more apparent further from the equator

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14
Q

Things we should know about orbit of earth:

A

Orbital speed (v): speed of planet orbiting a star
Orbital radius: (r) distance of planet from sun
(Earth’s orbital radius: 150,000,000km)
Orbital period (T): time taken for a planet to complete one full orbit around the sun
Distance travelled by planet: circumference of its orbit

v = 2πr/T
units: km/s or m/s

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15
Q

150,000,000Km to metres:

A

1.5x10^8 x 10^3 =
1.5 x 10^11metres

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16
Q

1 Year to seconds:

A

1 x 365 x 24 x 60 x 60 =
31536000s

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17
Q

What are months caused by?

A

Orbiting of moon around earth

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18
Q

What is the moon?

A

The moon is a rocky sphere which we only see when it reflects like from the sun since its a Non luminous object

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19
Q

The moon orbits earth fully every how many days?

A

27.5 days

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20
Q

The moon has 8 phases, what are the 4 main ones?

A

Day 0 - New Moon
Day 7 - First Quarter
Day 14 - Full Moon
Day 21 - Third Quarter

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21
Q

Which phase of the moon is this?

A

Full Moon

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22
Q

Which phase of the moon is this?

A

Waning Gibbous

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23
Q

Which phase of the moon is this?

A

Third Quarter

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24
Q

Which phase of the moon is this?

A

Waning Crescent

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25
Q

Which phase of the moon is this?

A

New Moon

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26
Q

Which phase of the moon is this?

A

Waxing Crescent

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27
Q

Which phase of the moon is this?

A

First Quarter

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28
Q

Which phase of the moon is this?

A

Waxing Gibbous

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29
Q

Contents of our Solar System

A
  1. Sun (star)
  2. 8 Planets
  3. Asteroid Belt
  4. Dwarf planets
  5. Moons
  6. Comets and Natural Satellites
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30
Q

Inner planets

A

4 Inner planets:
1. Mercury
2. Venus
3. Earth
4. Mars

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31
Q

What’s a feature shared by inner planets?

A

They are smaller than outer planets and rocky. Making them more dense than outer

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32
Q

Outer planets

A

4 Outer planets:
1. Jupiter
2. Saturn
3. Uranus
4. Neptune

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33
Q

What’s a feature shared by outer planets?

A

They are much bigger than inner planets and are huge balls of gases.
Making them less dense than inner

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34
Q

Whats the Asteroid Belt?

A

Rocky objects, which are much smaller than planets, located in the asteroid belt between orbit of mars and jupiter.

Seperates inner and outer planets

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35
Q

How many minor/dwarf planets are there and what are they?

A

5 have been recognized,
Such as Pluto and Eris

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36
Q

Function of moon

A

Orbit planets and dwarf planets.
Earth has only one
Some have more than one

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37
Q

Comets meaning

A

They are balls of ice, gas, rock and dust which orbit the sun in a highly elliptical orbit

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38
Q

Shape of comet FURTHEST from sun

A

Frozen, balls of ice, gas, rock and dust

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39
Q

Shape of comet CLOSEST from sun

A

As they get nearer, they heat up:
Leaving a trail of dust and gases behind them

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40
Q

What is the shape of planets orbit around sun?

A

Elliptical pathway

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41
Q

What force keeps planets orbiting sun and not flying outwards into space?

A

The Sun’s gravitational attraction force

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42
Q

Gravitation force formula:

A

Where:
F = gravitational force (N)
G = Gravity Constant (6.67x10^-11Nm2/kg2)

r^2 = distance between sun and planet
M1 = Mass of planet 1/Sun
m2 = Mass of planet 2

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43
Q

What percentage of the solar system does our sun’s mass make up?

A

99.8% of the mass of the solar system, which is why planets orbit it (because of its large gravitational force)

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44
Q

What is the most massive object in our solar system and is the centre of the solar system?

A

the Sun

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45
Q

What does the sun’s gravitational attraction force depend on?

A
  1. Mass of planet
  2. Distance between sun and planet
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46
Q

The sun’s gravitational force is DIRECTLY proportional to what

A

Mass of planet

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47
Q

The sun’s gravitational force is INDIRECTLY proportional to what

A

Distance between sun and planet

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48
Q

What is the true shape of all planets orbits?

A

Slightly that of a squashed circle, called an ellipse, thus has an elliptical orbit

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49
Q

What is the amount of how much the orbit of a planet is squashed?

A

Eccentricity

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50
Q

What has high eccentricity in our solar system

A

Comets

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51
Q

What has low eccentricity in our solar system

A

The earth and
The INNER planets

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52
Q

What is the wrong assumption of the sun’s location?

A

That the sun is located at the centre of elliptical orbit.
However its actually at a point called focus (point near centre of ellipse)

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53
Q

Sun’s true location:

A

The sun is at the focus of the elliptical path of each of the planets

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54
Q

Since the orbit of the planets is elliptical, what does this mean?

A

That planets move closer to and further away from the sun during each orbit

55
Q

What is the magnitude of energies on planet NEAREST to sun

A

Minimum GPE
Maximum Kinetic energy

56
Q

What is the magnitude of energies on planet FURTHEST from sun

A

Maximum GPE
Minimum Kinetic energy

57
Q

Explain the energy changes in orbit of planet:

A
  1. Gravitational force of sun remains the same.
  2. When planet is nearing the sun, radius decreases, so speed increases and moves fastest: GPE is transferred to KE.
  3. As it is moving away, KE decreases as radius increases, KE transferred to GPE, object slows down.
  4. Gravitational force of sun pulls object towards sun again, repeating energy changes.
58
Q

Why is KE and GPE energy fully conserved in space?

A

No resistive forces like friction or air resistance

59
Q

What are the two types of energy in an orbit?

A

GPE and KE

60
Q

What is a light year?

A

Distance travelled in space by light in a year

61
Q

Value of light year?

A

9.5 x 10^15 Meters

62
Q

How to get value of light year?

A

Distance = speed x time
speed = 3.0 x 10^8 (m/s)
time = 365 x 24 x 60 x 60 (s)

63
Q

What is the nearest star after the sun and how far away is it?

A

Proxima Centauri, it is 4.2 light years from Earth

64
Q

Time for light from sun to travel to earth?

A

Time = distance/speed
distance = 1.5 x 10^11 m
speed = 3.0x10^8 m/s

then convert into sec ,min, or hour

  • Same units!!!
65
Q

Scatter graph def:

A

A way of displaying two sets of data to see if there is a correlation or connection.

66
Q

What does the Solar system begin as and what is it?

A

Nebula: A huge swirling ball of interstellar clouds of dust and gas

67
Q

What is the motion of the interstellar clouds and what does it create?

A

The spinning motion of the interstellar clouds of dust and gas form a flat, spinning ring disc called an Accretion Disc

68
Q

Components of interstellar clouds:

A

Gas (mostly hydrogen)
Dust
Other elements

69
Q

Where do the other elements in interstellar clouds come from?

A

They are formed by fusion in other stars that have exploded at the end of their life cycle, sending their contents out into the clouds of interstellar gas

70
Q

How are protostars formed

A

interstellar clouds of gas and dus in stellar nebulas

71
Q

How is a protostar formed at the center of the accretion disc?

A

The force of gravity within a nebula pulls the particles closer together until it forms a hot ball of gas (protostar)

72
Q

What makes density and temperature of protostar increase?

A
  • As particles are pulled closer together, density of protostar increase
  • This results in more frequent collisions between the particles which causes the temperature to increase
73
Q

What happens when a protostar becomes hot enough?

A
  • Nuclear fusion reactions occur within its core
  • Hydrogen nuclei fuse to form Helium nuclei
  • Every fusion reaction releases heat and light energy which keeps the protostar core hot
74
Q

When is a protostar considered a main-sequence star?

A

Once a star initiates fusion

75
Q

What stage is our Sun in at the moment?

A

Main-sequence star

76
Q

In which stage is a star considered in equilibrium and a stable state?

A

During Main-sequence

77
Q

How are stars in main sequence stable?

A

The inward force of gravity is equal to the outward high temperature from the fusion reactions

78
Q
A

The outwards and inwards forces within a star are in equilibrium. The centre red circle represents the star’s core and the orange circle represents the star’s outer layers

79
Q

Once a protostar is formed, its life cycle will depend on its mass

A

Low-mass stars become a Red Giant star
High-mass stars become a Red SUPER Giant star

80
Q

Life-Cycle of Low-mass stars:

A
  1. Nebula
  2. Protostar
  3. Main-Sequence Star
  4. Red Giant
  5. Planetary Nebula
  6. White Dwarf
  7. Black Dwarf
81
Q

When do the fusion reactions in the core start to die down?

A

After several billion years when the hydrogen in the core causing the fusion reactions to begin to run out

82
Q

What happens when hydrogen in core runs out?

A

The core stars to shrink and heat up:

  • Inward force of gravity will be greater than outward force due to pressure of fusion reaction, as fusion dies down.
83
Q

What other series of reactions occurs when hydrogen runs out?

A

New fusion reacts are carried out:
Helium nuclei fuse to form beryllium nuclei

84
Q

What do the new fusion reactions cause?

A

These reactions will cause the outer part of the star to expand. Since more energy is released in fusion of helium than hydrogen due to larger mass.

So outwards pressure becomes greater than inwards force.

85
Q

What happens to a low-mass star that is up to 8 times the mass of the Sun or smaller?

A

Will become a red giant

86
Q

Why is a red giant red?

A

Because outer surface ofthe star starts to cool

  • Remember, orange/yellow is hotter than red
87
Q

What happens after second stage of nuclear fusions (helium) have finished in a red giant?

A

The star will become unstable and eject the outer layer of dust and gas

88
Q

What is the layers of dust and gas which is ejected called?

A

Planetary Nebula

89
Q

What happens to the core that is left behind after planetary nebula formed?

A

It will collapse completely, due to the pull of gravity, and the star will become a white dwarf.

90
Q

When is a black dwarf formed:

A

When the star has lost a significant amount of energy.
It will continue to cool until it eventually disappears from sight

91
Q

Life cycle of high-mass star:

A
  1. Nebula
  2. Protostar
  3. Main-sequence star
  4. Red Super Giant star
  5. Supernova
  6. Either a Neutron Star or Blackhole
92
Q

How does a Red Super Giant star form:

A

After several million years, hydrogen runs out.

the fusion reactions in the core will start to die down

core shrinks and heats up, making outer layer expand and contract

fusion reactions form elements all way up to iron, fusion reactions cannot continue past iron.

High-mass star (more than 8 times the mass of the Sun) will become a red supergiant

93
Q

What is the last element of nuclear fusions in a red supergiant and why?

A

Iron because it is the most stable element

94
Q

What happens once nuclear fusions inside red supergiant cannot continue past iron?

A

The core of the star will collapse suddenly and cause a gigantic explosion, called a supernova

95
Q

What happens at the centre of the supernova explosion?

A

A dense body, called a neutron star will form

96
Q

What happens to the outer remaining part of the red supergiant star?

A

They will be ejected into space during the supernova explosion, forming new clouds of dust and gas (nebula)

97
Q

What’s special about the nebula from a supernova?

A

May form new stars with orbiting planets

98
Q

What is left after a supernova explosion at its centre and how is neutron star formed?

A

After a supernova explosion, the star’s core is left. If the core is less dense, (smaller stars) it becomes a neutron star.

If the core is more dense, (bigger stars), it becomes a black hole

99
Q

What is a neutron star made of?

A

Made up of almost all neutron

100
Q

When is a blackhole formed?

A

If the core is more dense, mainly in bigger stars, it becomes a black hole

101
Q

How is a blackhole formed from a neutron star?

A

The neutron star that forms at the centre will continue to collapse under the force of gravity until it forms a black hole

102
Q

What is a blackhole?

A

A black hole is an extremely dense point in space that not even light can escape from.

103
Q

What is the Doppler effect?

A

For a moving object:
- Wavelength of waves infront of the source decreases and frequency increases

  • Wavelength behind the source increases and frequency decreases
104
Q

Red Shift vs Blue shift

A

Light from a star that is moving towards an observer will be blueshifted and light from a star moving away from an observer will be redshifted

105
Q

Galactic Red shift def

A

An increase in the observed wavelength of electromagnet radiation emitted from receding stars and galaxies

106
Q

What is this known as

A

This is known as redshift as the light shifts towards the red end of the spectrum, this is because light waves are stretched by the expansion of the universe so wavelength increase.

107
Q

What red shift prove?

A

That galaxies are moving away from us

Meaning that the universe is expanding

Supports the Big Bang theory

It means that everything expanded from a singular point called singularity

108
Q

what does Red shift-distance graph show?

A

The greater the distance to the galaxy, the greater the redshift.

Which means

The further away a galaxy, the faster it is moving away from us

109
Q

Big bang theory:

A

13.4 billion years ago Universe began from a single point that was extremely hot and dense, called singularity

Then big bang explosion happened

Universe expanded from a single point, cooling as it does so, to form the universe today

As a result of the explosion, the universe continues to expand

110
Q

How is red shift supporting the big bang theory? (those are galaxies)

A

Proves that each point expands away from each other, so universe is expanding.

This is seen by galaxies moving away from each other, the further away a galaxy, the faster it is moving away from us.

111
Q

Analogy:

A

At first all points same distance apart

As balloon expands, points become futher apart by same amount

This is because space itself expanded between galaxies

112
Q

Big Bang theory evidence:

A

1) Galactic red-shift
2) Cosmic Microwave Background Radiation (CMBR)

113
Q

What is CMBR

A

High energy radiation being redshifted over billions of years, thus Microwave radiation of a specific frequency is observed at all points in space around us

114
Q

What caused CMBR

A

the early Universe was an extremely hot and dense environment so it must have emitted thermal radiation (infra-red radiation)

115
Q

How did infra-red/high energy radiation become microwave?

A

Due to universe expansion, the wavelength of the radiation increased
Over time, it has increased so much that it is now in the microwave region of the spectrum

116
Q

How to find out the speed (v) at which a galaxy is moving away from the Earth

A

the change in wavelength of the galaxy’s starlight due to redshift (actual shift - expected shift)

117
Q

How can distance (d) of a far galaxy be observed?

A

Using the brightness of a supernova
in that galaxy

118
Q

What does this show

A

Light from more distant galaxies was more red-shifted than the light from nearer galaxies

119
Q

Hubble’s law:

A

The recessional velocity v of a galaxy is proportional to its distance from Earth

120
Q

Hubbles Law equation:

A

H0 = Hubble constant (second)
v = recessional velocity of an object, the velocity of an object moving away from an observer (km/s)
d = distance between the object and the Earth (km)

121
Q

Hubble Constant, H0 def:

A

The ratio of the speed at which the galaxy is moving away from the Earth, to its distance from the Earth

122
Q

Accepted value of Hubble’s constant?

A

H0 = 2.2 × 10–18 per second

123
Q

What does this represent?

A

Estimate of age of the Universe and is evidence for the idea that all the matter in the Universe was present at a single point

124
Q

For me:
What is Hubble’s constant exactly?

How is v proportional to d?

How is 1/H0 = age of universe

A
  1. tells us how fast the universe is expanding
  2. v=H0xd
  3. Unit of H0 = 1/s
    If you inverse 1/s to s, you get the inverse of how fast the universe is expanding, meaning you get the singularity point 13.4 billion years ago as time in (seconds)
125
Q

What is the milky way and what is its diameter?

A

Milky Way is one of many billions of galaxies making up the Universe

diameter = approximately
100,000 light-years

126
Q

where is the sun

A

the Sun is a star in the Milky Way galaxy (it is the closest star to earth)

127
Q

Feature of sun (fusions+emissions)

A

Medium-sized star in the milky way, consisting mostly of hydrogen and helium, and radiates most of its energy in the
infrared, visible and ultraviolet regions of the electromagnetic spectrum

128
Q

What are stars powered by?

A

by nuclear reactions
that release energy. powered by hydrogen as fuel

129
Q

Natural satellite:

A

Moons are an example of natural satellites

130
Q

Artificial satellite:

A

man-made things that can orbit any object in space

131
Q

What happens when distance of planet from sun increases?

A

Sun’s gravitational
pull decreases and orbital speeds of the
planets decrease (radius increases)

132
Q

differences in the types of planets are defined by what

A

accretion model for Solar System formation

133
Q

What happens when distance of planet from sun decreases?

A

Sun’s gravitational
pull increases and orbital speeds of the
planets increase (radius decrease)

Physics (10 decks)

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