Space Physics - Physics Paper 2 Flashcards
What can you use to remember the planets?
My Very Easy method Just Speeds Up Naming Planets
What do stars initially form from?
A nebula
What is a nebula?
A cloud of dust and gas
The force of gravity makes the gas and dust spiral in together to form a what?
A protostar
What happens after a protostar is formed?
Gravitational attraction causes the density of the protostar to increase and particles within the protostar collide with each other more frequently, so the temperature rises.
What happens when the temperature inside a protostar is high enough?
hydrogen nuclei undergo nuclear fusion to form helium nuclei. This gives out massive amounts of energy which keeps the core of the star hot. At this point, as star is born
What happens once a star is formed?
It enters a long stable period and is now a main sequence star, where the energy released by nuclear fusion provides an outward pressure that tries to expand the star , which balances the force of gravity pulling everything in (equilibrium).
What happens when the hydrogen in a star begins to run out?
fusion of helium occurs and the star is no longer a main sequence star
What produces all the naturally occurring elements in the universe?
Stars and their life cycles
What happens to small stars the size of the sun when they run out of hydrogen?
The star will expand into a red giant and will become red because the surface cools off. It will then become unstable and eject its outer layer of dust and gas as a planetary nebula. This leaves a hot white dwarf. As a white dwarf cools, it emits less and less energy. When it no longer emits a significant amount, it is called a black dwarf and eventually disappears from sight.
What happens to big stars when they run out of hydrogen?
They begin to expand into red super giants when they run out of hydrogen. They expand and contract several times, forming elements as heavy as iron in various nuclear reactions. Eventually, red super giants run out of elements to fuse and they become unstable. They then explode into a supernova , forming elements heavier than iron and ejecting them into the universe to form new planets and stars. Then, the exploding supernova throws the outer layer of dust and gas into space, leaving a very dense core called a neutron star. If the star is big enough, it will become a black hole instead
What’s a black hole?
A super dense point in space that not even light can escape from
What is the single star in our solar system called?
The sun
What are planets?
Large objects which orbit a star
What is an example of a dwarf planet?
Pluto
What are dwarf planets?
Plantet-like objects that orbit stars but are too small to meet all the rules for being a planet
What are satellites?
Objects that orbit a second more massive object , like a moon or an artificial satellite
What is a moon?
Natural satellites that orbit planets
What is a artificial satellite?
A man-made satellite that orbits planets
What provides the force that keeps an object within orbit?
gravity
What is an orbit a balance between?
The force providing the acceleration of the object in orbit and the forward motion (Instantaneous velocity)
What does the size of an orbit depend on?
The object’s speed
The closer you get to a star….
the stronger the gravitational force
The stronger the gravitational force….
the faster the orbiting object needs to travel to remain in orbit
for an object in a stable orbit, if the speed of the object changes, what must also happen?
the size of its orbit
if an object in a stable orbit moves faster, the radius of its orbit must be…
smaller so that the object remains close to the sun and doesn’t fly off in to space
if an object in a stable orbit moves slower, the radius of its orbit must be…
larger so that the object in orbit remains further away from the sun and doesn’t collapse into the sun
What is red-shift?
The idea that galaxies are moving further away from us and their wavelengths are increasing and shifting towards the red end of the spectrum.
More distant galaxies have a greater what than others?
A greater red shift
What is the whole universe doing?
Expanding
Are more distant galaxies moving further away than nearer ones?
yes
What does the big bang theory say?
That initially, all matter in the universe occupied a very small space . This tiny space was very dense and so was very hot. Then, all the matter exploded , space started expanding, and the expansion is still going on
What is evidence for the big bang theory?
Red shift
Do we know why the expansion of the universe is speeding up?
No
What is the universe mostly made up of?
Dark matter and dark energy
What is dark matter?
The name given to an unknown substance which holds galaxies together but does not emit any EM radiation.`
What is dark energy responsible for?
the accelerated expansion of the universe.
What might dark matter also be called?
Dark mass
Where are elements heavier than iron only produced?
In a supernova
