Unit 8 - Space Physics Flashcards
What does our solar system consist of
-one star
-the sun
-8 planets
-dwarf planets
-natural satellites
-moons
Where is our planet located
In the Milky Way
What are the 8 planets
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
What is the life cycle of a star for the size of the sun
-stars initially form from a cloud of dust and gas called a NEBULA, the force of gravity pulls the dust and gas together to form a PROTOSTAR
-as the star gets denser, the temp rises and more particles collide with each other
-when temp is high enough hydrogen nuclei undergo nuclear fusion to form helium nuclei
-this gives out huge amounts of energy
-the stars enter a stable period where the outward pressure caused by nuclear fusion balances the force of gravity pulling everything inwards, this period is called a MAIN SEQUENCE STAR
-eventually the hydrogen will run out and the sun swells into a RED GIANT
-it becomes red because the surface cools, fusion of helium occurs, heavier elements up to iron are created in the core of the star
-it will then become unstable and ejects its outer layer of dust and gas, this leaves behind a hot dense solid core - a WHITE DWARF
-as a white drawn cools, it emits less energy
-when it no longer emits a significant amount it is called a BLACK DWARF
What is the life cycle of a star much more massive than the sun
-stars initially form from a cloud of dust and gas called a NEBULA, the force of gravity pulls the dust and gas together to form a PROTOSTAR
-as the star gets denser, the temp rises and more particles collide with each other
-when temp is high enough hydrogen nuclei undergo nuclear fusion to form helium nuclei
-this gives out huge amounts of energy
-the stars enter a stable period where the outward pressure caused by nuclear fusion balances the force of gravity pulling everything inwards, this period is called a MAIN SEQUENCE STAR
-eventually the hydrogen runs out, the star then swells into a RED SUPER GIANT, it becomes red because the surface cools, fusion of helium and other elects occur,
-heavier elements up to iron are created in the core of the star
-it will then start to glow brightly again as they undergo more fusion and expand and contract several times forming elements as heavy as iron in various nuclear reactions
-they will then explode in a SUPERNOVA, forming elects heavier than iron and ejecting them into the universe to form new planets and stars
-the exploding supernovae throws the outer layers of dust and gas into space leaving a very dense core called a NEUTRON STAR
-if the star is massive enough it will instead become a BLACK HOLE which does not let light escape from
Role of gravity
-provides the force that allows planets and satellites (both natural and artificial) to maintain their circular orbit
Why is that for circular orbits there is a changing velocity but not speed
Velocity constantly changes because it is vector quantity and direction is constantly changing
Why does helium fusion require higher temperatures than hydrogen fusion
Helium has a bigger positive charge
So greater electrostatic charge
Need high speeds and high temperatures
How does size of orbit affect the objects speed
-closer you get to a star or planet the stronger the gravitational force is
-the stronger the 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 the size of orbit must to
What are planets
-large objects that orbit a star
-there are 8
-their gravity is strong enough to have pulled in any nearby objects apart from their satellites
What are moons
-these orbit planets
-they are a type of a natural satellite
What are artificial satellites
-are satellites that humans have built
-the generally orbit Earth
What is the red shift
-there is an observed increase in the wavelength of light from most distant galaxies
-the further away the galaxies the faster they are moving and the bigger the observed increase in wavelength
-this provided evidence that space itself is expanding and supports the Big Band theory
What is the Big Bang theory
-suggests that the universe began from a very small region that was extremely hot and dense
-the it exploded and space started expanding and the expansion is still going
How might new evidence change our theory
-scientist are discovering new evidence meaning they have to make a new Thiery or change a current one to explain what they have observed
-there is still lots we don’t know about the universe for example dark matter and dark energy
What is dark matter
Galaxies rotate faster than the visible mass can explain, there is a hidden mass everywhere in the universe
What is dark energy
Some force accelerating the expansion of the universe
How are stars formed
-from cloud of dust and gas which are pulled together by gravitational attraction
-as the density increases the temperature increases
-when temperature is high enough nuclear fusion happens and large amount of energy is emitted
