p8.3 Flashcards
what is redshift
the shift in wavelength of the light from distant stars and galaxies into longer waves (longer wavelength and frequency decreases)
if the source is moving faster the redshift is bigger
how does redshift provide evidence for the big bang
movement of galaxies provide evidence of the expanding universe
spaces between galaxies are expanding
the more distant a galaxy the faster it is moving
how does cosmic microwave background radiation provide evidence for the big bang
thermal radiation which fills universe uniformly
this is radiation left over from the big bang
what is a comet
objects made of ice and dust in orbit around the sun but with usuallly long and thin orbits
how is the sun formed
huge cloud of dust and hydrogen gas
gravity pulled both together and core became hot
particles moved fast enough for nuclear fusion
balance between gravitational attraction inwards and expansion of very hot gases outwards
lifecycle of red giants (like the sun)
very long main sequence lifetime
becomes a red giant
becomes planetary nebula
becomes white dwarfs
life cycle of super red giants
short main sequence lifetime
becomes super red giant
supernova
becomes neutron star or black holes
explain how the force of gravity can keep an object in orbit
gravitational force of object towards the planet
force changes direction of motion
accelerating even though speed does not change
what is a geostationary orbit
24 hours
36000 km
fixed position above equator
communications
satellite tv
what happens if speed of orbiting object changes
speed up - fly off
slow down - accelerate towards planets
closer to planet - faster
what does the radiation that an object depend on
warmer objects emit more thermal radiation
hotter the object , higher frequency of radiation emitted
what does the temperature of an object depend on
if object emits less radiation than absorbed , the temp increases
if objects emits more radiation than absorbed, temp decreases
how does the earths atmosphere effect the earths temperature
earth absorbs suns radiation
some radiation reflected back
intensity of reflection depends on conc of green house gases
inc conc means tens of earth increases
describe the structure of the earth
crust
mantle
outer core
inner core
describe p waves
primary
longitudinal
travel through solids and liquids
faster
describe s waves
secondary
transverse
cannot travel through liquid
slower
how to use detection of seismic waves to work out the structure of the earth
both s and p waves emitted through the earth
only p detected at the other end as s waves cannot travel through liquid
proving earths core must be liquid
low polar orbit
2 hours
2000km
orbits over poles
weather
observation of earth
military spying
