Topic 7 - Astronomy Flashcards
Describe the steady state theory
The universe has always existed but is expanding and creating matter to counteract the loss in density
Describe the Big Bang theory
The universe expanded from a very small dense point about 14 billion years ago
What is red shift?
A perceived increase in the wavelength of light due to the source moving away from the observer
What does red shift provide evidence for?
Universe is expanding
Supports 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 2 galaxies, one further away than the other
Galaxy further away is travelling faster
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?
Observed supernovae - suggested galaxies are moving away at ever faster rate
Prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?
Rate of expansion was expected to occur more slowly
Thought that gravitational forces would cause this slowing down
What does CMBR stand for?
Cosmic microwave background radiation
What does CMBR provide further evidence for?
Big Bang theory
Believed that CMBR originates from radiation produced in the big bang
How does the existence of CMBR support the expansion of the universe?
Thought that gamma radiation was released in Big Bang
Expansion of universe has stretched radiation = microwave radiation.
What factor determines the type of lifecycle a star goes through?
The size of the star
Which 2 phases do all stars the same size or bigger than the sun go through?
- Protostar phase
2. Main sequence phase
What do stars like the sun become at the end of their life cycle?
A black dwarf
What 2 things can stars much bigger than the sun become at the end of their lifecycle?
- Neutron star
2. Black hole
