P8 -Space physics Flashcards
definition : the big bang theory
It suggests that the universe has expanded from an initially very SMALL, HOT and DENSE point.
DEFINITION : dark matter
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
DEFINITION : dark energy
A hypothesised form of energy, believed to be responsible for the
universe’s ever increasing rate of expansion.
DEFINITION : Main sequence star
The stable state of all stars. The gravitational forces
pulling the star together, and the pressure pushing outwards, are balanced.
DEFINITION : Nebula
A cloud of dust and gas.
DEFINITION : 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.
DEFINITION : 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.
DEFINITION : red-shift
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.
DEFINITION : supernova
The EXPLOSION of a MASSIVE star, that distributes the elements
created by the fusion reactions in the star, throughout the universe.
DEFINITION : 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.
CLASS NOTES: Order of planets
My Very Evil Mother Just Served Us Noodles Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
CLASS NOTES: why is pluto a dwarf planet?
- It’s obit cuts into neptunes orbit
- its orbit is not a circle
- pluto is small (about the size of USA)
CLASS NOTES: What stops a star from collapsing?
Forces.
Gravity acting inwards.
Pressure from fusion pressing outwards.
CLASS NOTES: Lifecycle of a star
Nebula
Protostar
main sequence star
Red super Giant |||||||| Red Giant
Supernova |||||||| White dwarf
Neutron star |||||||| Black dwarf
CLASS NOTES: Creation of elements
Hydrogen and Helium - made shortly after the big bang.
HELIUM in stars - Created in MAIN SEQUENCE STAR with the P-P chain
Elements up to IRON - Made in MASSIVE STARS during their Giant phase.
Elements up to URANIUM - Made during SUPERNOVA explosions.
Elements above uranium - created by human beings in experiments.
CLASS NOTES: summary of red shift and big bang theory
- The absorption lines of distant galaxies are redshifted.
- They must all be moving further away from us.
- The further away they are, the faster they are moving away.
- The universe is expanding.
- The universe must have been smaller, hotter and denser in the past.
EXAM PRACTISE : what is a red shift?
wavelength (of light) increases
accept frequency decreases
or
light moves to red end of spectrum
accept redder but do not accept red alone
EXAM PRACTISE : What does the measurement of the biggest red-shift tell scientists about this star?
it is the star (detected) furthEST from the Earth accept galaxy for stars or it is moving away the fastEST
EXAM PRACTISE: Describe the ‘big bang’ theory.
all matter compressed from a single point (1)
massive) explosion SENDS matter outwards (1
EXAM PRACTISE: Explain why scientists believe that the Solar System was formed from the material produced when earlier stars exploded.
solar system contains heavy elements / elements heavier than hydrogen
and helium (1)
these (heavy) elements are / were formed by (nuclear) fusion (1)
(at the very high temperature(s)) in a super nova / when stars explode (1)
EXAM PRACTISE: Explain how the spectrum ‘shift’ of the dark line supports the theory that the Universe began from a very small point.
line shifts towards red end of spectrum (1)
wavelength (appears) to increase (1)
galaxy is moving away (from the
Earth) (1)
EXAM PRACTISE: Cosmic microwave background radiation (CMBR) is a type of electromagnetic
radiation. CMBR fills the Universe. It was first discovered in 1965 by two
astronomers called Penzias and Wilson.
(i) What do scientists believe is the origin of CMBR?
(radiation produced shortly after) ‘Big Bang’
EXAM PRACTISE: Why was the discovery of CMBR so important to the scientists believing the ‘Big Bang’ theory to be correct?
any one from: • can only be explained by ‘Big Bang’ • existence predicted by ‘Big Bang’ • provides (further) evidence for ‘Big Bang’ ignore proves ‘Big Bang’ (theory) ignore reference to red-shift
EXAM PRACTISE: How is the wavelength of CMBR likely to change, if at all, over the next billion years?
increases / universe continues to accelerate outwards/ greater red shift
