Topic 8-Space physics Flashcards
What galaxy is our solar system part of?
The Milky Way galaxy
How many planets orbit the sun
8
The sun lies at the centre of our solar system. What is the term used to describe this?
Heliocentric
What do the planets in our solar system orbit around and what type of body is it?
The planets orbit around the sun
The sun is a star
What type of force pulled together the cloud of dust and gas to form the Sun?
Gravitational force of attraction
Why might some planets rotate in the opposite direction or on a skewed axis to the other planets?
This may be due to past collisions throwing its axis balance
Why do some larger planets have rings?
Their gravitational field is so strong is attracts debris
What word is used to describe a cloud of dust and gas?
A nebula
What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?
Fusion reactions
What factor determines the type of lifecycle a star undergoes?
The size of the star
Initially, Earth was at the centre, the planets, our moon, and the sun, orbited the Earth
What term is used to describe this?
“Geocentric” model
Everything orbited in perfect circles with a fixed background of stars
Which two phases do all stars of the same or greater size than the sun undergo?
Protostar phase
Main sequence phase
What do stars of a similar magnitude to the sun become at the end of their life-cycle?
A black dwarf
Why might some planets rotate in the opposite direction or on a skewed axis to the other planets?
It is due to past collisions throwing its axis off balance
Why do larger planets have rings?
Their gravitational field is so strong it attracts debris
What two things can stars much bigger than the sun become at the end of their lifecyle?
Neutron star
Black hole
What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?
Red giant
White dwarf
What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?
Red super giant
Supernova
What are produced during the fusion processes in a star?
All of the occurring elements
What condition is required for fusion reactions to occur in a star?
Very high temperatures
How are elements heavier than iron produced?
In a supernova
What type of nuclei fuse together to form heavier elements in a star
Hydrogen nuclei to form heavier elements
How are elements distributed throughout the universe?
Through the explosion of a massive star (super nova)
What allows planets and satellites to maintain circular orbits?
Gravity provides the gravitational force that acts as the object’s centripetal force
The presence of a centripetal force allows for the object to maintain its circular orbit
What type of satellite can a planet’s moon be described as?
A natural satellite
Give two examples of artificial satellites
TV satellites
Satellites used for satellite imaging
Explain why for a stable orbit, the radius of orbit mist change if the speed changes
At higher speeds, the object requires a greater centripetal force
For a greater centripetal force, the gravitational force must increase
This is achieved by the radius of the orbit being reduced
Explain how the of gravity acting on a satellite affects its speed and velocity
The force can alter its velocity since the direction is continually changing
It can’t cause a change of speed since there is no force component in the direction of motion
What word is used to describe the sun’s position in our solar system?
Heliocentric
What happens as the planets orbit the sun?
The gravitational force causes the planet to change direction constantly (it moves in a circle around the sun)
This means the velocity is always changing
Hence the force causes the planet to accelerate without increasing its speed
Describe how a star is created
Dust and gas cloud is present in a galaxy
The gravitational attraction between the gas/dust particles draws them together
The cloud becomes more concentrated, as the particles get closer
The temperature and pressure of the cloud increases as the particles get pushed together
Eventually the pressure gets so great that the gas/dust particles are able to fuse together
What is red shift?
An observed increase in the wavelength of light from distant galaxies
What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
The further away a galaxy is, the faster it is moving
The further away a galaxy is, the greater the observed increase in wavelength
What does red-shift provide evidence for?
Provides evidence that the universe is expanding
Supports the Big Bang Theory
What does the Big Bang theory suggest?
The entire universe started from a very small, hot and dense region in space
Compare the observed red-shift of two galaxies, one further away than the other
The galaxy that is further away is travelling faster
The observed red-shift is greater the further away it is
What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?
They observed supernovae, which suggested that galaxies are moving away at an ever faster rate
Prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?
The rate of expansion was expected to occur at an ever slower rate
It was thought that gravitational forces would cause this slowing down
What two ideas could explain the universe’s ever increasing rate of expansion?
The existence of energy and mass that we can’t detect, known as dark matter and dark energy
These ideas are still being developed by scientists and are not yet fully understood
The observations made by Hubble support the idea that the Universe is expanding.
This means that galaxies are continually moving away from each other and from the Earth.
Figure 2 shows a student using a balloon to model the idea of an expanding Universe.
Some dots, which represent galaxies, were marked on the balloon. The balloon was then inflated.
Give one strength and weakness of this model
Strength: as the balloon expands, the dots get further apart, representing the galaxies moving apart
Weakness: Dots are only on the surface of the balloon, galaxies are throughout the universe
Weakness: There is a limit to how far the balloon can expand
Explain how the observation of galaxies moving away supports the Big Bang theory of the formation of the Universe
The furthest galaxies show the biggest red shift
This means that the furthest galaxies are moving the fastest
So the universe is expanding
This suggests that the Universe started from an initial point
State one of a piece of evidence that supports The Big Bang theory of the formation of the universe
CMBR (cosmic microwave background radiation)
Suggest what might cause scientists to stop supporting one theory and to start supporting an alternative theory
New evidence that supports/ disproves a theory
New evidence not supported by current theory
Why are telescopes that detect different types of electromagnetic waves used to observe the universe?
Stars/galaxies emit different types of electromagnetic waves/radiation
Describe The Big Bang theory
All matter comes from a single point.
A massive explosion sends matter outwards
Suggest what scientists would do if new evidence were found that did not support The Big Bang theory
They would take the reliability of the evidence
What is meant by red shift and what does it tell us about distant galaxies?
Longer wavelength waves
Galaxy moving away from the earth
Explain why scientists believe that the solar system was formed from the material produced when earlier stars exploded
Solar system contains heavy elements and these heavy elements were formed by nuclear fusion at very high temperatures in a supernova
Explain how the spectrum shift of the dark line towards the red side supports the theory that the universe began from a very small point
Line shifts towards red end of spectrum.
Wavelength appears to increase.
Galaxy is moving away from the earth
What does the size of the red shift tell the scientists about the distance the Galaxy is from the earth?
The bigger the red shift, the further the Galaxy is from the earth.
The light arriving from distant galaxies provide scientists have evidenced to support The Big Bang theory
Explain how
The lights shows a red shift which shows that galaxies are moving away
What do scientists believe is the origin of cosmic microwave background radiation?
Radiation produced shortly after The Big Bang
Why was the discovery of cosmic microwave background radiation so important to the scientists believing The Big Bang theory to be correct?
It can only be explained by The Big Bang
The smaller masses may be attracted by the star and become…
Planets
Our nearest star, the sun, is stable because the gravitational forces and the radiation pressure are….
Balanced
Explain why the sun will not go through the supernova stage but the star Mira will
Only very massive stars become supernova
Mira is large enough but the sun is too small
How is stars formed?
Dust and gas are pulled together by gravitational attraction
State why a star is stable during the main sequence period of its life cycle
The forces within it (gravity and radiation pressure) are balanced
Explain how stars like the sun were formed
They were formed from a giant cloud of gas and then condensed into a smaller volume by gravity
Describe what will happen to the sun from the time the hydrogen is used up until the sun dies
Fusion decreases or stops
The gravitational forces no longer balances pressure
The sun expands and becomes a red giant it then cools and then becomes a white dwarf
Explain what is meant by the term black hole
Mass with such a high density electromagnetic radiation/ light is pulled in
Shortly after The Big Bang, hydrogen was the only element in the universe
Explain how the other elements came to be formed
They are formed by nuclear fusion of hydrogen to helium
Elements heavier than iron are only produced in a supernova
Explain the difference between a protostar and a main sequence star
A protostar is at a lower temperature as fusion reactions have not started
Explain why the velocity of the satellite changes as it orbits the Earth
Force of gravity causes the satellite to accelerate towards the Earth
The acceleration causes a change in direction
Velocity changes because direction changes
