AQA Topic 8 - Space 9-1

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  • Created by: Grace
  • Created on: 21-04-18 22:03
What is a nebula?
A stars initial form of a cloud of dust and gas
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How is a Protostar formed?
The force of gravity pulls the dust and gas together to form a protostar
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From a protostar describe the conditions needed for a star
The temperature rises as the protostar gets denser and more particles collide with each other. When the temp gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei which gives out a lot of energy, this keeps the core hot=star
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What happens once a star is formed? (1)
It enters a long stable period where the outward pressure caused by the nuclear fusion that tries to expand the star balances the force of gravity pulling everything inwards. In this period a star becomes a main sequence star which typically lasts
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What happens once a star is formed? (2)
lasts 7 billion years. The Sun is in the middle of this stable period
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What happens once the hydrogen runs out? (1)
When the hydrogen runs out the star then swells into a red giant (sun size) or a red super giant (if its a large star). It becomes red because the surface cools. Fusion of Helium + other elements occurs. Heavier elements (up to iron) are
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What happens once the hydrogen runs out? (2)
created in the core of the star
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Describe the process after a star becomes a red giant
The star becomes unstable and ejects its outer layer of dust and gas which leaves behind hot dense solid core called a white dwarf
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Define a black dwarf
The stage after a white dwarf cools down and emits less and less energy. When it no longer emits a significant amount it becomes a black dwarf
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What happens after the Black Dwarf stage? (1)
Big Stars start to glow again as they undergo more fusion and expand contract several times, forming elements as heavy as iron in various nuclear reactions. Eventually they'll explode in a supernova, forming elements heavier than iron and ejecting
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What happens after the Black Dwarf stage? (2)
them into the universe to form new planets and stars. Stars and their life cycles produce and distribute all naturally occurring elements
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What does the exploding supernova cause?
The exploding supernova throws the outer layers of dust and gas into space, leaving a very dense core called a neutron star. If the star is massive enough it will become a black hole - a super dense point in space that not even light can escape from
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What is the solar system?
All the stuff that orbits our sun
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What makes up the solar system?
Planets, Dwarf planets, Moons and Artificial satellites
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What is our solar system part of?
The milky way galaxy, a massive collection of billions of stars that are all held together by gravity
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Name the planets in our solar system
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
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Describe the path of planets around the Sun
Circular orbits
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What does it mean if an object is travelling in a circle?
It is constantly changing direction, which means it is constantly accelerating which also means it is constantly changing velocity but not changing speed
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How do planets stay afloat? (1)
For an object to accelerate there must be a force acting on it, this force is directed towards the centre of the circle. This force would cause the object to fall towards whatever it was orbiting but as the object is already moving it just causes it
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How do planets stay afloat? (2)
to change its direction. The object keeps accelerating towards what its orbiting but the instantaneous velocity (which is at 90 degrees to the acceleration) keeps it travelling in a circle. The force that makes this all happen is provide by the
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How do planets stay afloat? (3)
gravitational force between the panel and the Sun or between the planet and its satellites
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True or False: The size of the orbit depends on the object's speed
True
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What happens the closer you get to a planet/star?
The closer you get the stronger the gravitational force is, the stronger the force the faster the orbiting object needs to travel to remain in orbit (as to not crash into the object its orbiting).
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What happens to an object in a stable orbit if the speed of said object changes?
The size(radius) of the of its orbit must do so to, faster moving objects will move in a stable orbit with a smaller radius than slow moving ones
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Define Red-Shift
Red-shift is where when we look at light from most distant galaxies find that the wavelength has increased, the wavelengths are all longer than they should be and have shifted towards the red end of the spectrum. Hence, Red-shift
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What does Red-Shift suggest?
This suggests that the source of light is moving away from us. Measurements of the red-shift indicate that these distant galaxies are moving away from us quickly (receding, like a receding hairline). It is the same result in every direction
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What is the evidence for the universe expanding?
More distant galaxies have greater red-shifts than nearer ones which means that more distant galaxies are MOVING away faster than nearer ones. This suggests that the whole universe, space itself, is expanding
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What is the basis for the Big Bang Theory?
All galaxies are moving away from each other at a great speed which suggests something must have got them going. That 'something' was probably a big explosion - the Big Bang
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Define the Big Bang Theory
Initially all matter in the universe occupied a small space, this tiny space was very dense and so was very hot. Then it 'exploded' - space started expanding and the expansion is still going on
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What do scientists currently believe the universe consists of?
Dark matter and Dark energy, Dark matter is the name given to an unknown substance which holds the galaxies together but does not emit electromagnetic radiation. Dark energy is thought to be responsible for the accelerated expansion of the universe
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Other cards in this set

Card 2

Front

How is a Protostar formed?

Back

The force of gravity pulls the dust and gas together to form a protostar

Card 3

Front

From a protostar describe the conditions needed for a star

Back

Preview of the front of card 3

Card 4

Front

What happens once a star is formed? (1)

Back

Preview of the front of card 4

Card 5

Front

What happens once a star is formed? (2)

Back

Preview of the front of card 5
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