space physics Flashcards
components of our solar system
- one star AKA the sun
- eight planets
- dwarf planets that orbit sun
- natural satellites
- moons that orbit planets
what is our solar system a part of
the milky way galaxy
how was the sun formed
from a cloud of dust and gas pulled together by gravitational attraction
what is a nebula
a cloud of dust and gas; how all starts start off
how does a nebula develop
gravitational attraction between dust and gas particles in nebula causes it to collapse and become more dense to form a protostar
what happens as gravitational force in a protostar strengthens
- protostar gains mass and becomes denser
- particles collide faster
- particles release more heat energy
what happens as a protostar becomes hotter and denser
- pressure and temp increase
- fusion reactions take place; hydrogen atoms fuse to form helium
what happens when fusion in a protostar starts
protostar becomes a main sequence star
how does a main sequence star develop
outward force due to fusion leads to equilibrium between star, allowing for a long, stable period that lasts billions of years
what happens as hydrogen runs out in a main sequence star
fusion will stop taking place
what happens when fusion stops taking place in a main sequence star
- forces become unbalanced
- inward force due to gravity outweighs outward force due to fusion
- star collapses in on itself
what happens when a main sequence star collapses in on itself
- becomes denser
- fusion between helium atoms take place
- heavier elements produced and star expands again
when a main sequence star expands again, what determines what it will expand into
the size of the star
as a main sequence star expands again, what happens if it was the same size as our sun
- expands into red giant
- fusion stops taking place
- collapses into small, dense core
- sheds outer layers of gas
- forms white dward
- emits all of its energy
- becomes black dwarf
as a main sequence star expands again, what happens if it was much larger than our sun
- expands into red super giant
- fusion stops taking place due to lack of sufficient pressure
- collapses
- heavier elements up to iron fuse
- fusion produces lots of energy
- star expands rapidly
- explodes into supernova
- temp and pressure high enough for elements heavier than iron to be produced
- elements distributed across universe
- star becomes neutron star or black hole depending on its mass
what is a neutron star
a solid dense core full of neutrons
what is a black hole
a star with such a large mass and density that even light cannot escape it
what do fusion processes do in stars
produce all naturally occurring elements
what is produced in a supernova
elements heavier than iron
what does a supernova do
the explosion of a massive star distributes the elements throughout the universe
what is the purpose of gravity in space
it provides the force that allows planets and satellites (both artificial and natural) to maintain their circular orbits
for circular orbits why can force of gravity lead to changing velocity but unchanged speed
orbits in a circle mean constant change of direction; velocity is speed in a given direction so it is changing. change in velocity.= acceleration, but overall speed is still the same, so velocity changes due to change in direction but speed remains constant
fake made-up equation for radius of an orbit
radius x speed = constant
dec radius = inc in speed
inc radius = dec in speed
in order to keep a stable orbit
what happens if radius of orbit decreases (i.e. gets closer to another planet for example)
speed has to increase to maintain stable orbit bc radius of orbit decreases, meaning grav attraction is much stronger than further away from earth
how can an object counteract the stronger gravitational attraction from a decreased orbit radius
travels at a faster speed to maintain a stable orbit. if too slow, would be pulled in towards the earth and vice versa
define red shift
the observed inc in the wavelength of light from most distant galaxed
what is observed about wavelength from the red shift
the further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength. this means it has shifted towards the red end of the spectrum bc red light has longest wavelength
what have scientists observed from the red shift
red shift is greater from distant galaxies than nearby; means that distant galaxies are moving faster away from us than nearby galaxies. this shows that the universe must be expanding
what does the red shift provide evidence for
- the universe’s expansion
- the big bang theory
what does the big bang theory suggest
the universe began from a very small region that was extremely hot and dense
what has been discovered since 1998 onwards
observations of supernovae suggest that distant galaxies are receding ever faster
how does the red shift provide evidence for the big bang
if the universe is constantly expanding, suggested by the red shift, then that must mean it was once much smaller and originated from a single point, which is in line with the big bang theory
what do we still not understand about the universe
dark mass and dark energy that we cannot detect because no EM radiation is emitted; they could perhaps explain why the expansion of the universe is speeding up
