Space (Chapter P16) Flashcards
How did the Sun form
The Sun formed at the centre of a spinning cloud of dust, gas and rock due to the force of gravitational attraction
This formed a protostar
As the protostar became denser, its particles sped up and collided more
This causes the temperature to increase, if it gets hot enough hydrogen nuclei form together starting fusion
How is the Solar system formed
The Sun formed at the centre of a spinning cloud of dust, gas and rock due to the force of gravitational attraction
The Sun’s heat evaporated ice and drove gas away from the inner solar system, leaving rocks behind
The rocky planets near the Sun and the gas giant planets formed further away
The minor planet Pluto orbits the Sun beyond giant planets
How does the Sun stay stable
It is stable because gravitational forces acting inwards balance the forces of nuclear fusion energy in the core acting outwards
What happens to stars around the size of the Sun
Once it runs out of hydrogen nuclei it reaches the end of its main sequence stage
Its core collapses, it swells out and cools down forming a red giant
When there are no more light elements to fuse together, fusion stops and the star collapses forming a white dwarf
A white dwarf is hot and dense but eventually cools and becomes a black dwarf
What happens to stars much bigger than the Sun
After the end of its main sequence stage it swells to become a red super giant and then collapses
In the collapse, the matter around the core compresses the core. The compression then reverses quickly in an explosion called a supernova
A neutron start is then formed and if the mass is big enough then a black hole is formed
What keeps a planet orbiting the Sun
The force of gravity between the Sun and the planet
Where is the gravity on an orbiting body in a circular orbit
Towards the centre of the circle
What happens as a body moves in a circular orbit
The velocity changes (but not the speed)
This is because the direction of the velocity changes and is always at right angles to the force
This means it experiences an acceleration towards the centre of the circle
What must a body do to stay at a particular distance
It must move at a particular speed around a larger body
What is red shift
It is the shift to longer wavelengths of the light from the other galaxy because it is moving away from you
What does a greater red shift mean
The faster a distant galaxy is moving away from you
What happens to the red shift when a galaxy is further away
The greater the red shift
What does red shift suggest
That all distant galaxies are all moving away from you because the Universe is expanding
What is blue shift
It is the shift to shorter wavelengths of the light from the other galaxy because it is moving to you
This is very rare
What is the Big Bang
It is a theory of how the universe was started
This is a massive explosion from a very small point
Space, time and matter were created in the Big Bang
