Space Physics Flashcards
What is the way of remebering the planets from the sun in order? (SS SP Ph)
My Very Easy Method Just Speeds Up Naming (planets ~ this is technically not a planet)
Mercury venus earth mars jupitor saturn uranus neptune
What are moons? (SS SP Ph)
natural satellites which orbit planets.
most planets in the solar system have at least one moon ~ some have a large number
What galaxy is our solar system in? (SS SP Ph)
The Milky Way Galaxy
What is a galazy? (SS SP Ph)
a massive group of stars
e.g the Milky Way contains hundreds of billions of stars and in the Universe, there are hundreds of billions of galaxies
How do stars form? (SS SP Ph)
stars form from a nebula
1. gravity causes the cloud of dust and gas to collapse.
2. as the dust particles move faster, the temperature rises to millions of degrees celcius. ~ protostar.
3. if the temperature of the protostar gets high enough then hydrogen nuclei join together to form helium ~ nuclear fussion
AT THIS POINT THE PROTOSTAR HAS TURNED INTO A STAR
4. nuclear fussion is now producing a lot of energy
What is a cloud of dust and gas called? (SS SP Ph)
a nebula
what is a nebula? (SS SP Ph)
a cloud of dust and gas ~ the gas is mainly hydrogen
What is a protostar? (SS SP Ph)
When a nebula begins to form a star the collapsing cloud of hot gas and dust.
What happens during nuclear fussion of a protostar? (SS SP Ph)
when it gets hot enough hydrogen nuclei join toegther to make helium nuclei. At this point there are two opposing forces acting within the star.
The force of Gravity acts inwards and tends to make the star collapse.
The energy from nuclear fussion creates a force acting outwards. This force tends to make the star expand
The force of gravity acting inwards is balanced by the force due to fusion energy acting outwards.
Because these two force are balanced, scientists say that the star is in equilibrium.
What is the main stage of a stars lifespan? (LOS SP Ph)
when the forces are balanced between gravity and nuclear fussion
What happens after the equilibrium stage of a star that is about the same size as the sun? (LOS SP Ph)
nuclear fussion requires hydrogen but when the star starts to run out of hydrogen the outwards force due to fusion energy is less than the inwards force due to gravity.
This causes the star to collapse inwards which causes the temperature to increase.
Now helium nuclei fuse together to create heavier elements and the star expands to form a red giant.
At some point the red giant stops fusing helium and the star shrinks and forms a white dwarf,
becuase the white dwarf is no longer carrying out fusion it gradually cools down.
Eventually it stops releasing energy and it forms a black dwarf
What happens after the equilibrium state of a star much larger than the sun? (LOS SP Ph)
Once this type of star runs out of hydrogen, they leave the main sequence stage and expand into red super giants.
helium nuclei fuse together to produce heavier elements
At some point the red super giant stops, carrying out nuclear fusion at this stage the star explodes and scientists call this a supernova
the temperature of a supernova is high enough to produce elements heavier than iron.
after the supernova, the remains of the star can form one of two objects
1. a neatron star ~ neautrons densly packed together
2. black hole that has such large amount of gravity that even light cant escape
When are elements heavier than iron produced? (LOS SP Ph)
in a supernova
What is the earths orbit like? (OM SP Ph)
almost circular but slightly eliptical
What holds planets in their orbits? (OM SP Ph)
the force of gravity
Wha do geostationary satellites do? (OM SP Ph)
they orbit once every 24 hours. so they always point to the same point of the earth
What causes the velocity to change of an object orbiting? (OM SP Ph)
the force of gravity holds objects in their orbit however in circular orbits the force of gravity is leading to a change in velocity but not speed which is constant.
What happens when the speed of an orbiting object changes? (OM SP Ph)
the radius of the orbit must also change. If the speed of a satellite increases then the radius of its orbit decreases as at a higher speed the satellite needs a greater force of gravity to prevent it flying off into space. So by moving closer to the earth, the gravitational force on the satellite is greater and the satellite remains in a stable orbit
What does the red shift tell us? (RS SP Ph)
that the galaxies are moving away from each other. because the galaxies are moving away, the light waves are stretched/ their observed wavelength is stretched.
Galaxies that are futher away have a bigger red shift so they are moving faster than galaxies that are closer.
What provides evidence that the universe is expanding? (RS SP Ph)
distant galaxies are moving faster than nearby galaxies provides evidence that the universe is expanding
What is the BIG BANG THEORY? (RS SP Ph)
most believe that the universe began from a very small region that was extremely hot and dense, this region then expanded into the Universe that we see today
how do we know that the universe is expanding faster? (RS SP Ph)
some assumed that gravity would cause the expansion of the universe to gradually slow down however observations of supernovae show that the rate of expansion is actually increasing. rather than slowing down, the universe is expanding faster
what is dark matter? (RS SP Ph)
the universe may conatain matter and energy the we cannot detect and they could explain why the expansion of the universe is speeding up (?)
