Space Physics Flashcards
what is in our solar system
the sun
the 8 planets
dwarf planets that orbit around the sun
natural satellites
example of natural satellites
the moons that orbit planets
what is our solar system a small part of
the milky way galaxy
how was the sun formed
from a cloud of dust and gas (nebula) pulled together by gravitational attraction
where does the sun lie in the solar system
the centre as it is heliocentric
planets in the solar system
mercury
venus
earth
mars
jupiter
saturn
uranus
neptune
(pluto)
acronym for solar system planets
my very early morning jam sandwich usually nauseates (people)
what are smaller planets made of
mainly rock
what are larger planets made of
mainly gas
where do planets orbit the sun from
all planets orbit the sun on the same plane
what do all planets do
orbit the sun
rotate
what are the differences in rotation of planets
different speeds
some rotate in the opposite direction or on a skewed axis to the other planets from a past collision throwing its axis off balance
why do larger planets have rings
their gravitational field is so strong it attracts debris
where was the earth initially
in the centre
with planets our moon and the sun orbiting it
features of the original solar system model
geocentric model
everything orbited in perfect circles
with a fixed background of stars
when was the heliocentric model formed
600 years after the initial model
what did the heliocentric model contain
the sun at the centre of
what was the evidence for the heliocentric model
mars retrograde motion
what is mars retrograde motion
earth orbits the sun faster than mars so we undertake it, so it appears to reverse its direction in the sky
what did galileo observe
moons orbiting jupiter
showing not everything orbited the earth
what did kepler show
the planets orbited in ellipses and not circles
what happens as the planet orbits the sun
the gravitational force causes the planet to change direction constantly as it moves in a circle
this means the velocity is always changing so the force causes the planet to accelerate without increasing its speed
what is needed for a stable orbit
if the planet moves closer to the sun eg its orbital radius decreases
the gravitational attraction to the sun increases meaning force and acceleration increase
so the orbital speed of the planet increases
features of mercury venus earth and mars
relatively small
rocky
what is a galaxy
a massive group of stars
how many stars does the milky way contain
hundreds of billions of stars
how many galaxies are in the universe
hundreds of billions of
what do stars form from
clouds of dust and gas called a nebula
what is the gas in a nebula
mainly hydrogen
what happens in the first stage of a star being formed
gravity causes the cloud of dust and gas to collapse
what happens as the dust particles move faster
the temperature rises to millions of degrees celsius
what is a protostar
a collapsing cloud of hot gas and dust
what happens if the temperature of the protostar gets high enough
hydrogen nuclei join together to form helium
what is nuclear fusion
hydrogen nuclei join together to form helium
what happens to the protostar when nuclear fusion occurs
the protostar has turned into a star
what is nuclear fusion doing once the protostar is a star
releasing a huge amount of energy
what happens within the star as it undergoes nuclear fusion
there are two opposing forces
what are the two opposing forces in the star
gravity
energy from nuclear fusion
what does gravity do in the star in nuclear fusion
acts inwards to the core
making the star collapse
what does the energy from nuclear fusion do to the star
creates a force acting outwards from the core
making the star expand
what happens to the two opposing forces in a star during nuclear fusion
the force of gravity acting inwards is balanced by the force due to fusion energy acting outwards
what does it mean when the two forces in the star are balanced
the star is in equilibrium
what kind of star is formed after nuclear fusion
a main sequence star
why do stars stay in the main sequence for a long time
nuclear fusion releases a lot of energy
what happens to a star the same size as the sun after being a main sequence star
the hydrogen in the star begins to run out
the outward force due to fusion energy is less than the inward force due to gravity
so the star collapses inwards
temperature increases
helium nuclei fuse together to create heavier elements
the star expands to form a red giant
at some point the red giant stops fusing helium
so the star shrinks and forms a white dwarf
the white dwarf isn’t carrying out fusion so it gradually cools
it stops releasing any energy and forms a black dwarf
what happens to stars bigger than the sun after the main sequence star stage
stars run out of hydrogen
leave the main sequence stage and expand into red super giants
helium nuclei fuse to produce heavier elements
red super giant stops carrying out nuclear fusion
the star explodes (supernova)
the temperature of the supernova is high enough to produce elements heavier than iron
when explodes these elements are distributed throughout the universe
remains of star can form a neutron star or a black hole
what can nuclear fusion not make
any element heavier than iron
what does a supernova make
elements heavier than iron
why do supernovas produce elements heavier than iron
the temperature is high enough
features of a neutron star
neutrons densely packed together
features of a black hole
such a large gravity that not even light can escape
what is the earth orbiting the sun known as
a circular orbit
what is the realistic orbit of the sun known as
an elliptical orbit
what is the earths orbit
virtually circular
how is the earth held in its orbit
gravity acting between the sun and the earth
what do planets do around the sun
orbit it
how do the planets stay in orbit around the sun
gravity holds the planets in their orbits
what is the moon an example of
a natural satellite
example of an artificial satellite
satellite used for satellite tv
who makes artificial satellites
man made
when do geostationary satellites orbit
once every 24 hours
what does geostationary satellites orbiting once every 24 hours mean
they always point to the same part of the earth
what is the frequency of other artificial satellites
more frequent than geostationary satellites
what does the force of gravity lead to in a circular orbit
a change in velocity but not a change in speed
what happens to the direction of a planet in orbit
it is constantly changing
what does the direction of the planet orbiting mean
the velocity is constantly changing as well
what happens if the speed of a satellite orbiting the earth changes
the radius of the orbit must also change
what happens if the speed of a satellite increases
the radius of its orbit decreases
why does the radius of an orbit decrease with an increase in satellite speed
at a higher speed the satellite needs a greater force of gravity to prevent it flying off into space
how does a satellite get a greater force of gravity
moves closer to earth
what is the impact of a satellite moving towards earth for greater force of gravity
remains in a stable orbit
what is the speed changing radius changing rule also true for
planets
moons
what did astronomers detect when studying light emitted from different galaxies
light from very distant galaxies has an increased wavelength compared to light from closer galaxies
what happens if you put light from the sun through a prism
it creates a spectrum
why do dark lines appear in a spectrum
certain elements in the sun absorb light of specific wavelengths so those wavelengths appear as dark lines
how is red shift shown
lines from light in a different galaxy have shifted slightly towards the red end of the spectrum
what does red shift tell us
galaxies are moving away from eachother
what is the impact of galaxies moving away
the light waves are stretched so observed wavelength is increased
what is the red shift of galaxies further away
bigger
how are galaxies further away moving compared to closer ones
moving faster
what does distant galaxies moving faster than nearby galaxies suggest
the universe is expanding
how do scientists believe the universe began
from a very small region
that was extremely hot and dense
that expanded to form the universe
what had astronomers previously assumed about gravity
it would cause the expansion fo the universe to gradually slow down
what did observations of supernovae show
the rate of expansion is increasing
what have scientists recently suggested the universe contains
matter and energy that we cannot detect
what are matter and energy we can’t detect called
dark matter
dark energy
what could dark matter and dark energy explain
why the expansion of the universe is speeding up
