Space Physics (Triple) Flashcards
Paper 2 - P8
What are the planets in order?
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
What is a moon?
A natural satellite which orbit planets.
How do stars form?
-Stars form from clouds of dust and gas called a nebula.
-In the first stage gravity causes the cloud of dust and gas to collapse and as the dust particles move faster the temperature rises to millions of degrees Celsius.
-The collapsing cloud of hot gas and dust is called a protostar.
-If the temperature of the protostar gets high enough then hydrogen nuclei join together to form helium and this process is called nuclear fusion.
-At this point, the protostar has turned into a star and nuclear fusion is now releasing a huge amount of energy.
How can a star be stable?
The force of gravity acting inwards is balanced by the force due to fusion energy acting outwards.
Describe the lifecycle of a star of stars that are about the same size as the Sun.
-In a main sequence star, hydrogen nuclei fuse together to make larger nuclei such as helium.
-At some stage the hydrogen in the star begins to run out. At this point the outward force to fusion energy is less than the inward force due to gravity.
-This causes the star to collapse inwards. The collapse of the star causes its temperature to increase.
-Now helium nuclei fuse together to create heavier elements.
-The star now expands to form a red giant. At some point, the red giant stops fusing helium.
-At this stage the star shrinks and forms a white dwarf because the white dwarf is no longer carrying out fusion, it gradually cools down.
-Eventually it stops releasing any energy and it forms a black dwarf.
Describe the lifecycle of a star of stars that are much bigger than the Sun.
-In a main sequence star, hydrogen nuclei fuse together to make larger nuclei such as helium.
-At some stage the hydrogen in the star begins to run out. At this point the outward force to fusion energy is less than the inward force due to gravity.
-This causes the star to collapse inwards. The collapse of the star causes its temperature to increase.
-Now helium nuclei fuse together to create heavier elements.
-Now the star expands into red super giants. At some point, the red super giant stops carrying our nuclear fusion.
-At this stage the star explodes into a supernova and the temperature of a supernova is high enough to produce elements heavier than iron.
-When the supernova explodes, these elements are distributed throughout the universe.
-After the supernova, the remains of the star can form one of two objects the first is called a neutron star which consists of neutrons densely packed together. Instead of forming a neutron star, the remains can form a black hole and a black hole has such a large gravity that not even light can esacpe.
What do scientists call the Earth orbiting the Sun?
A circular orbit as the Earth follows the path of a circle
How is the Earth held in its orbit?
The forces of gravity acting between the Sun and the Earth holds the Earth in its orbit.
What are the different types of satellites?
-Artificial satellites (man made)
-Geostationary satellites which orbit once every 24hours
In case of circular orbits what does the force of gravity lead to?
A change in velocity but not in speed
What happens if the speed of the satellite changes?
Then the radius of the orbit must also change e.g. if the speed of the satellite increases then the radius of its orbit decreases.
Why does a satellite need a greater force of gravity when its at high speeds?
So it doesn’t fly off into space
What is red shift?
When galaxies are moving away from each other and when they move away as the light waves are stretched.
How does red shift provide evidence for the universe expanding?
The fact that distant galaxies are moving faster than nearby galaxies provide evidence that the universe is expanding.
Where do scientists believe the universe began?
From a very small region that was extremely hot and dense which exampled to the universe we see today which is called the Big Bang theory.
