P8c Astrophysics Flashcards
What are the planets in our solar system?
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
What is a terrestrial planet?
A planet composed primarily of silicate rocks or metals
Which planets in our solar system are terrestrial planets?
Mercury, Venus, Earth and Mars
What is a gas giant?
A large planet composed mostly of gases, eg hydrogen + helium, with a relatively small rocky core
Which planets in our solar system are gas giants?
Jupiter, Saturn, Uranus and Neptune
How did the Sun form?
- Cloud of gas and dust (nebula) collapsed due to gravity
- This formed a protostar which continued to accumulate mass
- Temp and pressure became high enough for nuclear fusion
- Star went into stable period called main star sequence
Planets, moons and manmade satellites are all in ___
They are kept in it by ___ and travel in a ___ motion
Orbit
Gravity
Circular
Objects in the solar system travel in ___ ___. There is a relationship between their ___ and ___
Stable orbits
Speed
Radius
If the speed of an object in orbit increases, the radius of the orbit…
Decreases
If the speed of an object in orbit decreases, the radius…
Increases
Planets closer to the sun travel at a ___ speed
Faster
What happens when the radius of an object in orbit decreases?
Speed increases
In a main sequence star, ___ nuclei are fused together to form ___
This releases energy as…
Hydrogen
Helium
Heat and light
What stages are there in the life cycle of a small star (eg the Sun)?
Main sequence
Red giant
White dwarf
Black dwarf
What happens after the main sequence stage?
Eventually all hydrogen fuel runs out
Star cools and expands, becoming a red giant
Starts to fuse together helium nuclei to release energy
What happens after the red giant stage?
As helium fuel runs out, outward forces reduce in size and star collapses inwards
Temperature increases
White dwarf is formed, which is the hot core of the star
What happens after the white dwarf stage?
When the star completely cools the star becomes a black dwarf
Doesn’t emit any light or heat
What happens after the red giant stage for a large star?
Explodes in a supernova
What does a supernova produce?
Elements heavier than iron
A supernova leaves behind…
Either a black hole or a neutron star
The fusion processes in stars produce…
All naturally occurring elements
All stars fuse ___ nuclei into ___ in nuclear fusion
Hydrogen
Helium
Large stars fuse ___ nuclei into ___ and other ___
Hydrogen
Lithium
Light metals
The Doppler effect describes…
The observed wavelength and frequency of waves changing when the source moves with respect to an observer
In the Doppler effect, do the wavelength and frequency actually change?
No, they only appear to change
When the source of the waves is approaching…
The frequency shifts upwards for observers
When the source of the waves is receding…
The frequency shifts downwards for observers
What is red-shift?
As an object moves away from us, the wavelength of light it emits gets longer
The light gets redder as red has the longest wavelength
This effect is called red-shift
The faster an object is moving away from us…
The longer its wavelength gets and the redder it appears
How does red-shift provide evidence for the universe expanding?
Light from distant galaxies is red-shifted
The further the galaxy, the greater the red-shift, which means the further away it is, the faster it’s moving away from us
Which colour has the longest wavelength?
Red
What is the Big Bang theory?
The universe began from a very small, hot, dense region
It started expanding and is still expanding today
What is cosmic microwave background radiation (CMBR)?
Scientists have discovered microwave radiation coming from every direction
This is called cosmic microwave background radiation (CMBR)
It is the radiation produced by gas at low temps
Red-shift is evidence that the universe is…
Expanding
Which types of waves can be affected by the Doppler effect?
All types of wave
Moons are ___ satellites
Natural
Name 3 types of star
3 from:
Main sequence
Black dwarf
Red giant
White dwarf
Protostar
Supernova
