Topic 8 - Space Physics Flashcards
What is the lifecycle of a star?
Firstly, it is a cloud of dust and gas before becoming a protostar which leads to a main sequence star. Then depending on how big the star is it becomes a red supergiant or a red giant. A red supergiant leads to a supernova and then a neutron star or a black hole. A red giant leads to a white dwarf and then a black dwarf.
T/F: Planets in orbit are constantly changing speed but not velocity
False: Planets in orbit will change velocity whilst the speed remains the same
How do objects stay in orbit?
A force acts on the object (gravity) pulling it in to the centre of the circle, this means that the object is falling towards it but since it is already moving it causes a change in direction. The instantaneous velocity (which is always at a right angle to the acceleration) keeps it travelling in a circle.
Why do planets closer to the sun have a faster orbit?
The closer you get to an object the greater its gravitational force will be
What is a red shift?
An increase in wavelength which means a decrease in frequency and photon energy
What is the opposite of a red shift?
A blue shift which is a decrease in a wavelength and a simultaneous increase in frequency and energy
How do we know the universe is expanding?
The light we observe from distant galaxies has an increasing wavelength (they have experienced a red shift), this suggests that the source of light is moving away from us - it is the same in every direction we look
Where does the big bang theory come from?
If the whole universe is expanding the expansion had to start somewhere, this leads us to the conclusion that the universe once occupied a very small space which was hot and dense, one day the pressure got too much and it exploded which started expansion
What is dark matter?
A name given to an unknown substance which holds galaxies together but does not emit an electromagnetic radiation
What is thought to be responsible for the expansion of the universe?
Dark energy
