Topic 8 - Space Physics Flashcards
What are artificial satellites?
Man-made satellites that have been sent into space for purposes such as satellite imaging and communications.
What is the big bang theory?
The currently accepted model for the origin of the universe. It suggests that the universe has expanded from an initially very small, hot and dense point.
What is are circular orbits?
Planets and satellites travel in circular orbits. Gravity provides the required force for these orbits.
What is dark energy?
A hypothesised form of energy, believed to be responsible for the
universe’s ever increasing rate of expansion.
What is dark mass?
A hypothesised type of mass that cannot be observed by current methods. It is used to explain why some galaxies rotate faster than they should for their observed mass.
What is a main sequence star?
The stable state of all stars. The gravitational forces
pulling the star together, and the pressure pushing outwards, are balanced.
What is a milky way galaxy?
The galaxy in which our solar system is located.
What is a natural satellite?
The moon that orbit planets.
What is a nebula?
A cloud of dust and gas.
What is a protostar?
The first stage all stars go through after forming from a nebula. In this stage the star becomes hot enough for hydrogen nuclei to fuse.
What is a red giant star?
When their hydrogen is used up and larger nuclei are produced by fusion, stars of a similar magnitude to the Sun will expand to form a red giant.
What is the red shift?
The observed increase in the wavelength of the light emitted by distant galaxies. The more distant the galaxy, the faster it is moving and so the bigger the observed increase in wavelength.
What is the star life cycle?
The stages that a star passes through in its lifetime, dependent on the size of the star relative to the sun.
What is the sun?
A star formed from a cloud of dust and gas being pulled together by gravitational attraction. Fusion reactions occur in the sun.
What is a supernova?
The explosion of a massive star, that distributes the elements created by the fusion reactions in the star, throughout the universe.
What is a white dwarf?
When the fusion reactions in stars of a similar magnitude to the sun come to an end, the star will contract under gravity and cool down to form a white dwarf.
How many planets make up our solar system?
Eight (plus the dwarf planets)
What type of force pulled together the cloud of dust and gas to form the sun?
Gravitational force of attraction.
What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?
Fusion reactions.
Which two phases do all stars of the same or greater size than the sun undergo?
- Protostar phase
- Main sequence phase
What do stars of a similar magnitude to the sun become at the end of their life cycle?
A black dwarf.
What two things can stars much bigger than the sun become at the end of their lifecycle?
- Neutron Star
- Black Hole
What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?
- Red Giant
- White Dwarf
What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/ black hole?
- Red super giant
- Supernova
What are produced during the fusion processes in a star?
All of the naturally occurring elements.
What condition is required for fusion reactions to occur in a star?
Very High Temperatures.
How are elements heavier than iron produced?
In a supernova.
What type of nuclei fuse together to form heavier elements in a star?
Hydrogen nuclei fuse to form heavier elements.
How are elements distributed throughout the universe?
Through the explosion of a massive star (supernova).
What allows planets and satellites to maintain circular orbits?
- Gravity provides the gravitational force that acts as the object’s centripetal force
- The presence of a centripetal force allows for the object to maintain it’s circular orbit
Explain why for a stable orbit, the radius of orbit must change if the speed changes?
- At higher speeds, the object requires a greater centripetal force
- For a greater centripetal force, the gravitational force must increase
- This is achieved by the radius of the orbit being reduced
Explain how the force of gravity acting on a satellite affects it’s speed and velocity.
- The force can alter it’s velocity since the direction is continually changing
- It can’t cause a change of speed since there is no force component in the direction of motion
What does red- shift provide evidence for?
- Provides evidence that the universe is expanding
- Supports the big bang theory
What two thing can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
- The further away a galaxy is, the faster it is moving
- The further away a galaxy is, the greater the observed increase in wavelength
Compare the observed red- shift of two galaxies, one further away than the other.
- The galaxy that is further away is travelling faster
- The observed red- shift is greater the further away it is
What two ideas could explain the universe’s ever increasing grate of expansion?
- The existence of energy and mass that we can’t detect, known as dark matter and dark energy
- These ideas are still being developed by scientists and are not yet fully understood.
