Space Physics Flashcards
describe the formation of stars
nebula ( cloud of gas and dust). Gravity causes this to spiral together to form a protostar. gravity causes the density to increase and particles collide more frequency so temperature rises.
when it gets hot enough, hydrogen nuclei begin to undergo nuclear fusion to form helium nuclei
at this point a star is born
explain what happens through the life of a main sequence star
energy released by nuclear fusion gives outward force, balanced by the force of gravity pulling inwards. equilibrium. its like this for several billion years. when hydrogen runs out fusion of heavier elements occurs up to iron in the core occurs .
what happens to a star about the same size as the sun when it dies
expand into a red giant when it begins to run out of hydrogen. becomes red because the surface cools.
it will then become unstable and eject its outer layer of gas and dust as a planetary nebula.
this leaves behind a hot dense solid core (white dwarf)
when it no longer emits a significant amount of energy it is a black dwarf and eventually disappears from sight
what happens when a star much bigger than the sun dies
explode into red super giants when they run out of hydrogen. they explode and contract several times forming elements as heavy as iron in nuclear reactions.
eventually they run out of elements to fuse and become unstable and explode in a supernova, forming elements heavier than iron.
this leaves a dense core called a neutron star. If the neutron star is big enough, it will become a black hole.
what are 3 things the sun is orbited by
planets
dwarf planets
satellites
what are satellites
objects that orbit a second more massive object. for example moons and artificial satellites
explain how a planet stays in orbit
the planet is accelerating towards the sun because the force of gravity is pulling to the sun. However the motion of the object (instantaneous velocity) is pulling it a a right angle to the force
how does speed of an object effect the radius of an objects orbit
if the object moves faster the radius must be smaller
what is red shift
when you looks at light from a distance the wavelength increases, causing it to move to the red end of the spectrum
it occurs when the source of the light is moving away from the observer
how do we know the universe is expanding
the light from over galaxys has been red shifted suggesting it is moving away from us. More distant galaxys have a greater red shift than nearer ones suggesting they are moving away quicker
what is the big bang theory
all matter was occupied in a very tiny, hot, dense space.
then it exploded and started expanding, and is still expanding now
what are 3 unexplained things about the universe
galaxies are accelerating away at faster and faster speeds but dont know why
dark matter is an unknow substance which holds galaxies together
dark energy is thought to be responsible for the accelerated expansion of the universe
no one knows what these things are
