p.8.3 Flashcards
what is red shift
this is when a light source moves away from you it looks more red than it truly. this is because as it moves away the wavelength increases meaning the frequency decreases and it shifts closer to infrared.
if the light source is moving towards you it will appear more blue
what is the big bang theory
scientists believe that the universe started around 13.7 billion years ago when something incredibly dense and smaller than an atom began to suddenly expand. the evidence for this is that all the galaxies are moving away from us
what other evidence is there for the big bang
in 1960 scientists noticed that microwave radiation was coming from every direction. this was cosmic microwave background radiation (CMBR). this was left over from the big bang. originally this radiation was very high frequency and high energy but over billions of years it had been stretched to microwaves
what does our solar system consist of
the sun
the planets
moons
minor planets - this is anything that orbits around the sun that isn’t a planet or comet, incudes dwarf planets and asteroids
comets - objects that orbit the sun. made out of ice and dust
what are the 4 inner planets, compare them
the four inner planets are mercury, Venus, earth and mars.
all these planets have atmospheres. mercury and mars have very thin atmospheres.
Venus’s atmosphere is mainly carbon dioxide and it rains sulphuric acid.
Mars has two moons, earth has one, mercury and Venus have none.
what are the 4 outer planets, compare them
Jupiter, Saturn, Uranus and Neptune
Jupiter and Saturn are ‘gas giants’
Uranus and Neptune and ‘ice giants’
all these planets have many moons
how was the sun formed
scientists think that there was a giant cloud of hydrogen and dust. gravity pulled them together. the intense pressure create very high amount of energy. eventually , due to the energy the particles were moving fast enough for nuclear fusion to occur. now the an equilibrium of gravitational attraction inwards and expansion of hot gas outwards exists
describe the life cycle of stars similar to our sun
1 - dust and hydrogen pulled together by gravity
2 - reaches equilibrium, stars in this state are called main sequence stars
3 - eventually the hydrogen begins to run out and the star begins to expand to become a red giant
4 - the star no longer has enough energy to sustain its massive size. it then collapses in on itself and becomes a white dwarf
describe the life cycle of a star around 20 times the mass of the sun
1 - born in cloud of dust and hydrogen due to gravity
2 - reaches equilibrium (this is called main sequence, and it is a lot shorter than the same period in a star similar to the sun)
3 - eventually hydrogen runs out and the star expands to a super giant
4 - the super giant then collapses under its own gravity
5 - then energy s so great that a supernova takes place.
6 - then a neutron star or black hole is formed
what are natural and artificial satellites
natural satellites - are objects that orbit around something in our solar system, made from the same thing as everything else in our solar system
artificial satellites - these are what we humans have sent to orbit around the planets
what are the 2 types of orbit and how do they differ
geostationary - this satellite maintains stationary above the equator, 36000 km above earth each orbit is 24hrs .
polar orbit - orbits over the poles, around 2000 km above earth each orbit takes 2 hours
why are orbits circular
because the force of gravity always acts towards the centre of the object. this means if the object that is orbiting is traveling fast enough the object will travel over the horizon as fast as gravity pulls it down
what happens if objects in orbit speed up or slow down
if the object is are in stable orbit and then speed up then it will fly off as the gravitational energy will not be strong enough to contain it
if it slows down then it will be pulled into the gravity source
what dictates the radiation an object emits, how can you use this information
the temperature, the hotter the object the higher the frequency of radiation.
using this information we can plot the heat of far away stars. hot stars more blue
less hot stars red
what is the temperature of an object dependant on
temperature depends on the radiation absorbed and emitted.
if they absorb more radiation than they emit the will heat up
if they emit more radiation than they emit then they will cool down
