P16 -Space Flashcards
What is at the center of the solar system ?
The sun
-The Sun is star
How many planets are there ?-There are eight main planets orbitting the sun .
In order FROM CLOSESTS TO THE SUN
MERCURY , VENUS , EARTH , MARS
-Are relatively small rocky planets .
In order CLOSEST TO THE SUN (2)
JUPITER , SATURN , URANU AND NEPTUNE
-are much larger
Then finally … pluto
-Beyond the orbit of Neptune , we have a number of dwarf planets .
-One of these is pluto . Dwarf planets , are extremely small .
The solar system contains a number of other objects besides planets . These include moons , asteroids , and comets . ONLY NEED TO DESCIBE MOONS .
Moons are natural satellites which orbit planets .
-Most of the planets in the solar system hav at least one moon . Some have a large number of moons .
The solar system is a tiny part of the milky way
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What is a galaxy
-A galaxy is a massive group of stars.
-The milkyway has hundres of billions of stars .
-aND IN THE UNIVERSE THERE ARE HUNDREDS OF BILLIONS OF GALAXIES .
how do stars form ? NEED TO KNOW
-Stars form from clouds of dust and gas . Scientists call a cloud of dust and gas a NEBULA . In a NEBULA the main gas is HYDROGEN
Stage one of the formation of a star .
-Gravity causes the cloud of dust and gas to collapse .
Stage two of the formation of a star .
-As the dust and particles move faster , the temperature rises to millions of degrees celcius .
-Scientits call this collapsing cloud of hot gas + dust A PROTOSTAR .
Stage three of the formation of the star.
-If the temperature of the protostar gets highe nough , then HYDROGEN nuclei join together to form HELIUM . This process is called nuclear FUSION .
Stage four of the formaiton of the star .
-At this point , the potostr hs turned into a STAR .
-NUCLEAR FUSION is now releasing a huge amount of energy .
Check diagram on sheet .
KEY THERE ARE TWO OPPOSING FORCES ACTING WITHIN A STAR.
One force acting on a star .
-The force of gravity acts inwards and tends to make the star collapse .
-The green arrows show the force of gravity .
The second force acting on the star
-The energy from nuclear fusion creates a force acting outwards . This force tend to make the star EXPAND .
-SO the force of gravity acting inwards is balanced by the force due to fusion energy acting outwards .
-As these two forces are balances scientist say that the star is in equililibrium .
S1 of a stars life .
-A stars life begins as a cloud of dust+gas . Scientists call this a NEBULA .
S2 of a star life .
-Gravity cuases the cloud of gas to collapse .
S3 of a stars life
-As the particles move gasyer , the temperature rises to millions of degrees celcius . This early stage is called a PROTOSTAR .
S4 of a stars llife .
-If the temperature gets high enough , then hydrogen nuclei join together to form HELIUM NUCLEI .
-This process is called nuclear fusion ,a t this point we have a MAIN SEQUENCE STAR .
-Nuclear fusions releases a hue amount of energy , stars can stay in the main sequence for a very long time .
But what happens next depends on the size of the star .
NEED TO LEARN THE DETAILS .
What happens to a star that is about the same size as the sun ? S1
-Hydorgen nucleir fuse togetehr to form eavier heliumnuclei .
-At some stage in a star , hydrogen beings to run out .
What happens to a star that is about the same size as the sun ? S1
-Hydorgen nucleir fuse togetehr to form eavier heliumnuclei .
-At some stage in a star , hydrogen beings to run out .
What happens to a star that is about the same size as the sun ? S2
-At this point , the outward force , due to fusion energy , is less than the inward force due to gravity .
What happens to a star that is about the same size as the sun ? S3
-Causing the star to collapse inwards .
-The collapse of the star causes the temperature to increase .
What happens to a star that is about the same size as the sun ? S4
-Now helium nuclei fuse together to make heavier elements . THe star expands to form a RED GIANT .
What happens to a star that is about the same size as the sun ? S5
-At some point , the red giant stops fusing helium .
-At this stage , the star shrinks and forms A WHITE DWARF .
What happens to a star that is about the same size as the sun ? S6
-As the white dwarf is no longer carrying out fusion , it gradually cools down .
-Eventually , it stops releasing any energy and it forms a black dwarf .
However STARS MUCH BIGGER THAN THE SUN , follow a different pattern .
NEED TO LEARN
STARS MUCH BIGGER THAN THE SUN
-Once those stars (mentioned before) run out of hydorgen , they LEAVE , the main sequence stage and expand into a RED SUPER GIANT .
-Once again , helium nuclei fuse together to produce heavier ELEMENTS .
REALLY IMPORTANT POINT IN FUSION .
-In the stages seen so far , nuclear fusion cannot make any element HEAVIER THAN IRON .
-So where do elements HEAVIER THAN IRON COME FROM .
ELEMENTS HEAVIER THAN IRON ;
-aT SOME POINT , THE RED SUPER GIANT stops carrying out nuclear fusion .
-At this stage the star EXPLODES - scientist call this explosion a SUPER NOVAAA.
-tHE TEMPERATURE OF A SUPERNOVA IS HIGH enough to produe elements heavier than IRON .
ELEMENTS HEAVIER THAN IRON ARE ONLY PRODUCED IN A …
SUPERNOVAAA
-wHEN A SUPERNOVA explodes , these elements re distributed throughout the universe .
…
After the supernova , the remians of the stars can form two objects .
-A neutrons tar
-A black hole
What is a neutron star ?
-Consits of neutrond densely packed together /
what is a black hole ?
-A black hole has SUCH A LARGE GRAVITY , that not even light can escape .
The earth orbitting the sun ;
-Scientists call this a circular orbit , as the Earth follows the path of a circle .
-Virtually , the Earth’s orbit is circular .
-But acutally scientists say that planets oribt in an elliptical shape .
-the force of gravity acting between the sun and the Earth , holds the Earth in its orbit .
KEY ; planets orbit the sun and the forceo f gravity holds them in their orbits.
THE MOON - is a in a circular orbit around the Earth .
-The moon is a natural satellite .
-Once again , the force of gravity holds the mmoon in its orbi .
ARTIFICAL SATELLITES
-Are MAN - MADE .
-Geostationary satellites orbit once every 24hrs .
-Meaning they always point tot he same part of the Earth (other satellites orbit more frequently).
Velocity , is the speed of an object ina given direction .
-If the SPEED of the satellite changes , then the radius of the orbit must also change .
If the speed of the satellite INCREASES…
…then the raidus of its orbit decreases .
-That is because at a higher spped , the satellite needs a greater force of gravity , to prevent it from flying off inot psace .
So by moving closer to the Earth …
the gravitational force on the satellite is greter and the satellite remains in a stable orbit .
-This is also true for planets and moons as well
In the 1900s , astronomers were looking at light emitted from different galaxies .
-They detected that light from very DISTNT , galaxies ahd an INCREASED WAVELENGTH , compared to light form closer galaxies .
If we take light from the sun , and pass it through a prism , then we get a spectrum .
-There are darklines in the spectrum , as certain elements in the sun , absorb light of specific wavelengths , so those wavelengths appear as sarklines .
If we take light from the sun , and pass it through a prism , then we get a spectrum .
-There are darklines in the spectrum , as certain elements in the sun , absorb light of specific wavelengths , so those wavelengths appear as sarklines .
If we take light from the sun , and pass it through a prism , then we get a spectrum .
-There are darklines in the spectrum , as certain elements in the sun , absorb light of specific wavelengths , so those wavelengths appear as darklines .
If we take light fromm a distant galazy and put it through a prism ?
-The lines had shiftedn slightly towards the RED END , of the spectrum , scientitss call this to RRED SHIFT
RED SHIFT
-TELLS US THAT GALAZIES ARE MOVING AWAY FROM EACHOTHER .
-As the galaxies are mainlu away the light waves are streched . AKA thier observed wavelength has increased .
RED SHIFT
-TELLS US THAT GALAZIES ARE MOVING AWAY FROM EACHOTHER .
-As the galaxies are mainlu away the light waves are streched . AKA thier observed wavelength has increased .
Galaaxies that are further away …
HAVE A BIGGER RED SHIFT , so these GALAXIES are movign FSTER then glaaxis thar are closerr .
Nearby galaxies have a small red shit …
showing these are moving away .
MOre distant glaaxies …
have a larger redshift , theya re moving away FASTER .
VERY DISTANt galaxies…
VERY LARGE REDHSOT , THEY ARE MOIVNG AAWAY VERY FAST
The fact that distant galaxies are moving faster than nearby galaxies
provides evdience that the unvierse is expanding
THE BIG BANG THEORY
-SCIENTISTS BELIEVE THAT THE UNIVERSE BEGAN FROMA VERY SMALL REGION THAT WAAS CTREMELYHOT AND DENSE .
-This region then expnded into the universe ,w e see todya , scientists call this the BIG BNG THEORY .
Around 1988 , astronomers discovered something large
-they had assumed gravity , would cuase the expansiono f the uiverse to gradually slow down .
-However , observaions of the supernovae , show hat the rate of expnsion is actually increasing .
-so rtaher than slowing odwn , the universe is expanding fasyer .
-SCIENTSS CAN’T EASILy explain this .
In recent years
-scientits suggested that the universe contaisn mtter and energy we cannot detect .
-This is called dark matter and egergy .
-It is possible that there woudl explain whyt he expansion of the universe is speeding up .
