space Flashcards
(15 cards)
satellite
an object which orbits a second more massive object
asteroid
a small rocky objedct which orbits the Sun
(asteroid belt between mars and jupiter)
comets
balls of rock and ice and dust and orbit the sun
meteor
bits of dust/rock burning as they move through Earth’s atmosphere
differenece between comets and meteors
comet stays and returns, whereas a meteor burns quickly and disappears
galaxy definition
a collection of billions of stars and their solar systems held together by gravity
nearest galaxy = Andromeda M31
formation of the sun
formed from massive clouds of dust and gas (nebula)
gravity pulled this cloud together into a giant ball
as the nebula collapsed the centre of this ball got very dense and hot and began to rotate
eventually nuclear fusion was able to begin and a dense protostar was formed—our Sun
equilibrium in stars
inward pull of gravity and the outward pressure acting on the star are equal
the outward force due to nuclear fusion is balanced by the inward force of gravity
if the temp of a star increases, the outward pressure will also increase, causing the star to expand
if temp drops, the outward pressre will also decrease, causing the star to contract
formation of stars
- Nebula—cloud of dust and gas
- Protostar—gravity within the nebula pulls the particles closer together until it forms a hot ball of gas, known as a protostar. density increases, so more frequent collisions, so temp increases
- Protostar becomes denser and its temp increases so it gets hotter. The nuclei of hydrogen fuse together forming helium nuclei and energy is released. becomes main sequence star
what happens to stars the same size as the sun
in main sequence star, hydrogen nuclei fuse together to make larger nuclei such as helium.
when hydrogen begins to run out, the out ward force due to fusion energy is less than the inward force due to gravity
causes the star to collapse inwards, which causes temp to increase, so now helium nuclei fuse together to create heavier elements, so the star expands to form a red giant,
when the red giant stops fusing helium, the star will collapse on themselves due to the pull of gravity and the star will become a white dwarf.
the white dwarf gradually cools down as it is no longer carrying out fusion. it eventually stops releasing energy and forms a black dwarf.
what happens to starts larger than the sun
once the protostar becomes hot enough, nuclear fusion reactions occur within its core
then the main sequence star will start to run out of hydrogen. So they expand into red super giants
helium nuclei fuse together to produce heavier elements
when the red super giants stops carrying out nuclear fusion, the star collapses under gravity so that the star explodes—this explosion = supernova. the temp of supernova is high enough to produce elements heavier than IRON
supernova distributes elements throughout the universe, e.g. carbon and oxygen (hydrocarbons in organic matter), iron (centre of the earth)
the supernova either leaves a neutron star in the centre, or forms a black hole, which is so dense that not even light can escape
how to maintain stable orbit
if the speed increases, the radius must decrease,
if the speed decreases, the radius must increase
doppler effect
the change in frquency or wavelength due to the relative motion between a source and an observer
red shift
the change in colour of light waves caused by a source of light moving away from an observer
opposite = blueshift
when a source of light is moving away from an observer the wavelength fronts are stretched out. the wavelength of the light increases. the light appears to be redder in colour
centripetal force definition
when an object travels on a circular path, there is a resultant force acting towards the centre of the circle
it is at right angles to direction of motion
the centripetal force between the moon and the earth is gravitational field strength
