P16 - Solar system Flashcards
comets
frozen rocks that move around sun
comets orbit
elliptical shape
- squashed circle
birth of a star
-nebula becomes increasingly concentrated
- clouds merge to forma protostar
- protostar become denser so temp increases
- hot enough = nuclear fusion = brighter star
nebula
-clouds of dust/gas pulled together by gravity
protostar becomes denser meaning
particles speed up more and collide more
- transfers energy from gpe to thermal store
hotter star =
nuclei of H fuse
- releases energy
- gets hotter and brighter
main sequence stars
-radiation from H fusion in core
-main stage of life cycle
fusion in core of main sequence star
- keeps it hot
- continues fusion
- gamma flows out steadily from core in all direction
star is stable when
-forces within are balanced
- equilibrium
forces within a star
- gravity contracts star inwards
-balanced by outward force of radiation from nuclear fusion
(to expand)
when a star runs out of hydrogen nuclei to fuse
reaches end of the main star sequence stage
-core collapses
- other layers swell out
- become red giants
red giants eg
sun
red giant
- helium and other light elements fus in core to form heavier element
red giant - when fusion stops
- its own gravity = collapses in
- as it collapses, it heats up = white dwarf
red giant to
yellow giant to white
white dwarf
hot dense white star
much smaller
white dwarf then
fades out
-goes cold to form black dwarfs
stars bigger than the sun
ends life after main sequence stage
- swell out and become red super giant + collapse
red super giant collapse
-matter in star’s ore compresses the core more and more
- supernova
supernova
explosion
- can outshine a galaxy for weeks
after suprnova
neutron star is formed
- or a black hole
when is a black hole formed
after a supernova
-only if there’s enough mass
light elements
from fusion in stars
-nuclear fusion
red giant fuses
helium and small nuclei = larger nuclei
nuclei larger than iron cannot be formed
as that required too much energy
heavy elements come from
supernova
- enormous force fuses small nuclei into bigger than iron nuclei
- scatters elemnts throughout univers
debris from supernova
has all elements
-pulled together to form new stars
neutron star
supernova compresses core into this
- very dense + made from neutrons only
gravity in black hole
so great
noting can escape
-formed only if a star is big enough
earth orbits
sun in a circular shape
moon orbits
in a circular shape
orbit
one body orbits a much bigger body always
-gravity between them
centripetal force
gravity on planet from centre of sun
planets velocity
changes by centripetal force
direction of motion of a planet is
at a right angle to the direction of the force of gravity
planet in circular orbit
-acceleration towards centre of circle from resultant force
acceleration
change of velocity per second
change of velocity
directed towards the centre
-speed doesn’t change
satellites too close to earth
lose speed
fall inwards
satellites in circular orbit above earth
moves at a constant height
stable orbit
to stay in a stable orbit =
particular speed
if launch speed is too high
satellite flies into space
if launch speed is correct
constant height
speed of orbit
the further a satellite or planet is in orbit
less speed needed to stay in circular orbit (less gravity)
- longer it takes to move around
time for each complete orbit =
circumference/ speed
if speed changes in stable orbit
radius must change (height of orbit)
communications satellites
orbit at 36 000km
-period of 24 hrs
- orbit same direction as earth’s spin (stays above same places as they move)
-geostationary
monitoring satellites
- fitted with tv cameras
- include weather forecasting
- much lower in orbit
-orbit once every 2/3 hrs
wavelength of light increases from
blue to red
light waves are stretched if
star/galaxy is moving away
red shift
wavelengths increase
-moves away
blue shift
light waves are squashed
-star moving towards
- wavelength is reduced
dark spectral lines
caused by absorption of light by specific atoms
(shows which shift is happening)
bigger shift =
the more the waves are squashed/stretched
faster the star/galaxy is moving towards you
the bigger the shift is
edwin hubble
light from distant galaxies was red shifted
- further a galaxy is from earth = bigger the red shift
he found that
distant galaxies are moving away from earth
greater distance in red shift =
greater speed of recession = greater red shift
universe is
expanding
- after exploding from small hot dense point
big bang theory
space, time, matter created from explosion of small hot dense point
cosmic microwave background radiation
EM radiation only explained by big bang theory
as universe expands
it has stretched wavelength to microwaves
dark matter
missing mass in galaxy
-cannot be seen
dark matter purpose
-bends light
holds galaxy together
doesn’t emit EM
