P8- Space Physics Flashcards
Which galaxy is our solar system part of
The Milky Way galaxy
How many planets make up our solar system
Eight (plus the dwarf planets).
What do the planets in our solar system orbit around
and what type of body is it?
● The planets orbit around the sun
● The sun is a star
What type of force pulled together the cloud of dust
and gas to form the Sun?
Gravitational force of attraction.
What word is used to describe a cloud of dust and
gas?
A nebula
What type of reactions take place at the start of a
star’s life cycle as dust and gas is drawn together
Fusion reactions
What factor determines the type of lifecycle a star
undergoes?
The size of the star.
Which two phases do all stars of the same or greater
size than the sun undergo?
- Protostar phase
2. 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
2. 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
2. 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
2. 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 its
circular orbit
What type of satellite can a planet’s moon be
described as
A natural satellite
Give two examples of artificial satellites
- TV satellites
2. Satellites used for satellite imaging
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 its speed and velocity
● The force can alter its 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 is red-shift
An observed increase in the wavelength
of light from distant galaxies.
What two things 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
What does red-shift provide evidence for?
● Provides evidence that the universe is
expanding
● Supports the Big Bang theory
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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 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 did scientists observe to provide
evidence that the universe is expanding
at an ever faster rate
They observed supernovae, which
suggested that galaxies are moving
away at an ever faster rate.
Prior to observations of supernovae, what was
believed about the rate of expansion of the universe
and why
● The rate of expansion was expected to
occur at an ever slower rate
● It was thought that gravitational forces
would cause this slowing down
What two ideas could explain the universe’s ever
increasing rate 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
