Space Flashcards
Where does the sun lie in our solar system?
In the centre
What is the sun?
A star which takes up 99% of the mass of the solar system
How many planets are there in our solar system?
8
What are the 4 rocky planets in our solar system?
Mercury, Venus, Earth and Mars
What are the 4 gas planets in our solar system?
Jupiter, Saturn, Uranus and Neptune
What are moons?
Natural satellites
Apart from planets, what also orbits the sun?
Asteroids
They are small rocky objects
Where is the asteroid belt?
Between Mars and Jupiter
What are comets made of?
Dust and ice and orbit the sun in a different orbit to planets
The ice melts when the comet approaches the sun forming the comets tail
Where is our planet?
In a small part of the milkyway
What does our milkyway have
Billions of stars
Some of the stars have planets which orbit them
How is the sun formed?
The sun is formed from massive clouds of dust and gas called nebula
The gravity pulled this cloud together in a giant ball
As the nebula collapsed the centre of this ball got very hot and dense and began to rotate
Eventually, nuclear fusion could begin and formed a protostar (our sun)
What are stars held together by?
A balance of inward forces (gravity) and outward forces (pressure)
The pressure force is exerted from the expanding hot gases inside of the stars
Gravity is an attractive force which pulls the outer layers inwards
What is meant by the star being in equilibrium?
When the outward pressure force and the inward gravity forces are equal to each other.
What happens if the temperature of the star increases?
The outward pressure will increase causing the star to expand
What happens if the temperature of the star decreases?
The outward pressure will also decrease causing the star to contract
(The temperature may drop due to nuclear fusion slowing down)
How have all naturally occuring elements been formed?
By nuclear fusion in stars
ONLY HYDROGEN HASNT BEEN FORMED THIS WAY.
What is nuclear fusion?
When two light nuclei join at a high speed to form a larger nucleus
For example when two hydrogen nuclei fuse they form helium
The process of nuclear fusion releases heat and light energy
As only elements lighter than iron can be formed in nuclear fusion, how is iron formed?
They are formed in supernovae explosion
A supernovae occurs at the end of a stars life
When the star explodes it release very large amounts of energy and neutrons
ALL THE ELEMENTS THROWN OUT OF THE EXPLODED STAR COMBINE TO FORM ELEMENTS HEAVIER THAN IRON
1st Stage of a stars life
NEBULA
Stars form from a giant cloud of dust and hydrogen gas called nebula
2nd Stage of a stars life
PROTOSTAR
The force of gravity within a nebula pulls the particles closer together until it forms a hot ball of gas (protostar)
As the particles are pulled closer together the density of the star will increase
(MORE COLLISIONS AND HIGHER TEMPERATURE)
3rd Stage of a stars life
MAIN SEQUENCE STAR
Once the protostar gets hot enough, nuclear fusion reactions occur within the core
Hydrogen will fuse forming helium
Every fusion reaction releases heat and light energy which keeps the core hot
What is the star described as being in the main sequence?
At equilibrium
Solar mass stars
RED GIANT
After billions of years the hydrogen causing fusion will start to run out
Causing the core to shrink and heat up
( THE CORE SHRINKS AS THE INWARD FORCE OF GRAVITY IS GREATER THAN THE OUTWARD FORCE OF PRESSURE FROM THE GAS EXPANDING AS FUSION DIES DOWN)
New fusion reactions will start like Helium into Beryllium.
This causes the outer part of the star to expand
It is red as the outer surface starts to cool
Solar mass stars
PLANETARY NEBULA
Once the second stage of fusion reactions have finished
The star will become unstable and eject the outer layer of dust and gas
(PLANETARY NEBULA)
Solar mass stars
WHITE DWARF
The core which is left will completely collapse due to the inward force of gravity
Becoming a white dwarf
The white dwarf will cool and keep decreasing in energy
Solar mass stars
BLACK DWARF
When its lost a lot of energy it will become dark
What are larger mass stars?
Stars much larger than the sun
They have much shorter life spans because they burn fuel of the nuclear fusion much quicker
Larger mass stars
RED SUPER GIANT
Main sequence star loses hydrogen in its core, fusion reaction starts to die down causing the core to shrink and heat up.
The force of gravity is greater than the force of pressure
Helium will fuse forming beryllium
The outer part of the star will expand forming RED SUPER GIANT
Larger mass stars
SUPERNOVA
Once the fusion reaction in the super red giants core have finished, the core will collapse suddenly causing a huge explosion
SUPERNOVA
What forms at the centre of the supernovae explosion?
A dense body of neutrons
Neutron star
Larger mass stars
NEUTRON STAR AND BLACK HOLES
In the case of the biggest stars, the neutron star will continue to collapse under the force of gravity forming a black hole
A black hole is an extremely dense point in space that nothing can escape from
When does a supernovae happen?
At the end of a stars life
The star must be bigger than the sun
What does a supernova reaction release?
Loads of energy
During the explosion, all the elements that were formed by the fusion are exploded out along with the neutrons
What do the neutrons that have been exploded out of the supernovae explosion do?
The fuse together forming heavier elements
These elements are then ejected into the universe forming planets and stars
What is orbital motion?
A smaller body or object will orbit a larger body or object
Gravity is needed for the two bodies to attract eachother
Hence the gravitational force exerted is always attractive
GRAVITATIONAL FORCE IS THE CENTRIPETAL FORCE
What do planets travel around the sun in?
In exactly circular orbits
They travel at a constant speed and they are constantly changing direction
If a planet is orbiting and constantly changing direction, what else is it doing?
If it is constantly changing direction then it is constantly changing velocity
Acceleration is the rate of change in velocity so if the direction and velocity are always changing then the object is accelerating
What is needed the cause acceleration?
A resultant force
For planets the resultant force is gravity
What are the similarities in the way planets orbit the sun?
All are slightly eliptical
All orbit the same plane
All orbit in the same direction as the sun
Differences in the way planets orbit the sun
All orbit at different speeds
All orbit at different distances
All take different times to complete their orbits
How do moons orbit?
How many moons do planets have?
And what happens if the moon is closer to the planet?
In a circular path
Some planets have more than one
The closer the moon, the shorter time take to orbit and the greater the speed it orbits at
What are artificial satellites?
What do they need to do?
What happens if the speed of them are too big or small?
Man made satellites that can orbit any object in the solar system
The need to travel at the right speed in order to stay in orbit
Too big and it falls of the orbit into space
Too small and gravity will pull it in towards the object
How do comets orbit the sun?
In a very elliptical orbit
What does the comets orbit shape mean?
It means that as the comet approaches the sun it picks up lots of speed and loses gravitational potential energy and converts it into kinetic energy
As the comet moves away it slows down
THIS IS CALLED THE SLINGSHOT EFFECT
What is the red shift?
The red shift is light taken from distant galaxies that shows that the light spectrum has shifted towards the red end.
This indicated that the galaxies are moving away from us and that the universe started from a big bang/ explosion
What is the doppler effect?
A moving object will cause the wavelength and frequency to change
What is the big bang theory?
14 Billion years ago the universe started from a very hot and dense point
There were a series of explosions known as the big bang
This caused the universe to expand and cool
As a result of the explosion the universe is still expanding today
Evidence for the big bang
By observing light spectrums from supernova there is proof that distant galaxies are moving further and further away faster and faster.
The light spectrum shows that the distant galaxies has red shifted
This is what happens in an explosion
Going back in time, if the planets and galaxies were closer and closer, what would we see?
If the galaxies were closer and closer, then they would all come together at a single point
So if the galaxies were grouped together, and then exploded we would see a similar effect.
What is dark matter?
There are still many observations that are not understood by astronomists, such as the rotation of galaxies, which suggests there is more matter in space than we account for
What is dark energy?
The measurements from supernovae suggest that the rate at which galaxies are moving from us are faster and faster, which suggests that there is dark energy that is increasing this rate.
