P16 - Space✔️ Flashcards
Describe what is in our solar system?
One star, eight planets and the dwarf planets that orbit the sun - natural satellites, the moon that orbits planets
Explain how the sun was formed?
Formed from a cloud of dust and gas (nebula) pulled together by gravitational attraction
Explain how a prostar is formed?
Dust and gas pulled together - as the temperature rises the star gets denser and more particles collide with ecah other - hydrogen nuclei undergo nuclear fusion for form helium nuclei - which gives out lots of energy and keeps the stars core hot
Describe the conditions when a star is in its main sequence?
Star enters a long stable period where the outward pressure caused by nuclear fusion (that tries to expand the star) balances the force of gravity pulling everything inwards - lasts several billion years
Explain what happens when the stars hydrogen begins to run out?
The star then swells into a red giant (if its a small star) or a red super giant (if its a larger star) - becomes red as the surface cools - fusion of helium and other elements occurs and heavier elements (up to iron) are created in the core
What happens after a red giant becomes unstable?
Will leave behind a white dwarf which will then cool down and become a black dwarf
Explain how a small/medium star becomes a white dwarf?
Red giant becomes unstable and ejects its outer layer of dust and gas - leaving behind a hot dense solid core
Explain how a white dwarf becomes a black dwarf?
As white dwarf cools down it emits less and less energy - when it no longer emits a significant amount, it is called a black dwarf
Give the order of a small/medium stars life?
nebula → prostar → main sequence star → red giant → white dwarf → black dwarf
Explain how a red super giant explodes in a supernova?
Starts to glow brighter as they undergos more fusion and expands and contracts several times, forming elements as heavy as iron in various nuclear rections - eventually they explode, forming elements heavier then iron and ejecting them into the universe
Explain how all naturally occuring elements are distributed in the universe?
Through the explosion of a supernova - which ejects elements heavier than iron into the universe to form new planets and stars
Explain how a neutron star is formed from a supernova?
Supernova throws the outer layer of dust and gas into space - leaves behind a very dense core (neutron star)
Explain how a black hole can form?
After a supernova and if the star is larger enough enough a black hole can form - a super dense point where not even light can escape
Give the life cycle of a large star?
main sequence star → red super giant → supernova → neutron star / black hole (if star is big enough)
Define a planet?
Large objects which orbit a star
Define dwarf planet?
Planet-like objects that orbit stars - don’ meet all requirments to be a star
Define moon?
Natural satelite - orbit planets
Define artificial satelite?
Are satellites that humans have built
Effect of a stronger gravitational force on an orbitting object?effects of changes in speed?
Will need to travel faster to remain in orbit - if the speed changes, the radius of its orbit must do so too - faster moving objects will have a stable orbit with a smaller radius
Evidence that the universe is expanding?
wavelength from light traveling from different galaxies has increased more towards the red end of the spectrum (red-shift) suggest light is moving away from us - further away galaxies have greater red-shifts indicating they are moving futher then closer galaxies
Explain the theory of the big bang?
Initially all the matter in the universe occupied a very small space which was very dense and very hot - then it exploded and space started expanding and is still expanding now
Define dark matter?
Name given to an unknown substance which holds galaxies together - but does not emit any electromagnetic radiation
Define dark energy?
Thought to be responsible for the accelerated expansion of the universe
