Space Physics Flashcards
what does the solar system consist of?
the Sun, plus the eight planets and dwarf planets that orbit the Sun. Natural satellites like moons that orbit planets are also part of the solar system.
what galaxy is the solar system part of
The milky way
what is the closest galaxy to the milky way?
Andromeda
Similarities in the orbit of every planet
They all orbit in the same direction and plain around the Sun
8 planets in order of closest to furthest from the Sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
smallest planet
mercury
biggest planet
Jupiter
how was the sun formed
The Sun was formed from a cloud of dust and gas (nebula) pulled together by gravitational attraction.
birth of a star
- dust, gas and hydrogen (nebula) condense as they are attracted by gpe.
- gpe –> kinetic energy, temperature and pressure increases and heats enough to emit light, becomes protostar.
- the protostar increases in temperature until nuclear fusion occurs in the protostar, releasing it into its main sequence.
longest phase of a stars life
Main Sequence
what happens in the main sequence of a star
the star fuses hydrogen into helium in its cores
what keeps a star from collapsing due to gravity in its main sequence
The forces are balanced because there is gravitational forces acting inwards on all directions to the star and radiation pressure and heat pushes outward from the nuclear fusion
what is the end stages of a star the similar size of the sun
Red giant -> White Dwarf -> Black Dwarf
what needs to happen to form a red giant
star burns through hydrogen supply
what happens in a red giant
- combines helium to make bigger atoms
- outer shell greatly expands engulfing things in its path
- core collapses inwards, becomes denser
- stars outer layers spread out and cool
how is a white dwarf formed
a red giants outer shell dissipates and forms a planetary nebula, leaving behind the core that is the white dwarf
what happens in a white dwarf
the star eventually runs out of helium to fuse; however, the mass of the former star does not produce enough gravity to continue fusing carbon and oxygen into heavier elements, thus the core of a white dwarf is inert.
how is a black dwarf formed
When a white dwarf exhausts its own supply of carbon, oxygen and free-flowing electrons, it will slowly burn out, transforming into a black dwarf.
why are there no black dwarfs
universe not lasted long enough for it to existed, so it is theoretical
what happens to stars bigger than the Sun
Red Supergiant > Supernova > neutron star / black hole
how does a red supergiant form
when a massive star runs out of hydrogen
how does a supernova form
when a star reaches the end of its life and the pressure drops low enough, the gravity blows the outer layers in a giant explosion called a supernova. Supernovae are the most powerful explosions in the universe and can create new atomic nuclei
how is a black hole formed
a black hole is formed from the remnants of a supernova from a star that collapsed
what is a black hole
a singularity which has such a strong gravitational force that no matter can escape
how is a neutron star formed
if a star is a bit less massive than the ones that form black holes, the central core and the remnants of the star collapse, crushing every proton and electron into a neutron
does size impact a stars lifetime
yes, the bigger the star the shorter the life
why do smaller stars live longer
the greater the mass, the higher the rate of nuclear fusion, leading to the star burning through hydrogen quicker therefore resulting in a shorter life cycle
Why does the amount of hydrogen in a star decrease over time
the nuclear reactions in a stars core require fuel, mainly hydrogen. over time, the star burns through its hydrogen for fuel, and as the concentration of hydrogen in the core decreases, the stars power output lowers, causing an imbalance between outward radiation pressure and inward gravitational pressure, and when the hydrogen burns out fully the balance would be totally lost, resulting in the star collapsing
where and how are all naturally occuring elements produced
through nuclear fusion
how are elements heavier than iron formed
in a supernova which distributes the elements throughout the universe
why do scientists think that the Sun and solar system were formed out of the remains of a supernova
there are heavy elements that have had to be produced in a supernova in this solar system.
how are heavy elements formed in a supernova
nucleosynthesis occurs with rapid successive neutron capture, followed by beta decay to form heavier elements
how do fusion processes lead to the formation of new elements
Nuclear fusion is when two or more nuclei collide at nearly the speed of light and join to form a new type of atomic nucleus. This creates new elements. Hydrogen and helium nuclei can then be fused into heavier elements.
what allows planets and satellites to mantain their circular orbit
the force that gravity provides
do all planets orbit the sun in the same direction
yes
what is a natural satellite.
any celestial body in space that orbits around a larger body, (moons)
how do planets and satellites move
Planets and satellites move in orbits. When planets go around the Sun, they are moving in an orbit. These orbits are circular (or almost circular) and are maintained by the force of gravity. Similarly, satellites will move around planets in a circular orbit too.
orbit of planets
natural, orbiting a star and circular or almost circular
orbit of natural satellites
natural, orbiting a planet and circular or almost circular
orbit of artificial satellites
manmade, orbits a planet (usually earth), and is circular
2 types of orbits for artificial satellites
geostationary and polar
geostationary orbits for satellites
communication satellite, orbits above the equator in a fixed path, 24 hours per orbit, same region of earth all day - synchronised with the rotation of earth
polar orbits for satellites
earth monitoring & observation satellites, over north & south poles, crosses equator twice per orbit, provides more detailed information about the weather + images and whole earth photos
is velocity scalar or vector
vector which has both size and direction, so speed and direction of movement is both important
two ways velocity of objects in orbit can be changed
direction of orbit, speed of orbit
how does direction of orbit change the velocity of objects in orbit
if the direction of an object changes, then the velocity of the object will change. The force of gravity keeps objects in their orbits. Gravity can change the direction but not the speed of a planet. The force of gravity is acts at right angles to the direction of travel.
how does speed of orbit change the velocity of objects in orbit
if the speed of the planet changes, then the velocity will change. However, the force of gravity is unable to change the speed of a planet, so planets have constant speed of orbit.
what force acts on objects in orbit
centripetal force
how do we know that there is centripetal force
an object moving in a circle is changing direction, its speed is constant, velocity changing. therefore it must have an accelerator. The direction of acceleration is towards the circle, and so therefore there must be a force acting towards the centre of a circle.
what is a centripetal force
any force that causes circular motion, acting towards the centre of a circle (perpendicular to the direction of motion).
what is the formula for centripetal force
centripetal force (F) = mass (m) x velocity (v) squared (^2) / Radius (r)
what needs to change for the speed to change in a stable orbit
the radius
why does the radius need to change for the speed to change in a stable orbit
The greater the acceleration, the greater the change in velocity - this causes the object to move faster. This means that objects in small orbits travel faster than objects in large orbits. In order to change orbital speed, an object must change the radius of its orbit at the same time, to maintain a stable orbit.
what would happen if the speed of the object in stable orbit changes
If the speed of the satellite is too low: The radius of the orbit will decrease and the satellite will move towards the object it should be orbiting. This is because the gravitational attraction is too strong to maintain a constant orbital radius.
what is red shift
as a source moves towards an observer, its frequency appears higher. As it moves away, its frequency appears lower
what did Edward Hubble discover about red shift.
Light from distant galaxies was red shifted. The further a galaxy is from the earth, the bigger its red shift is.
Red shift effect in space
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.
what happens to the wavelength in red shift
it appears longer
how can we tell how far something is from earth
The longer the wavelength, the further the light is from the earth.
how can we tell if galaxies are moving
The wavelengths we see are continuously increasing, which means that the galaxies are getting more and more ‘distant’ from Earth. To put this more simply, if a galaxy has a very large increase in wavelength, it means that the galaxy has moved very far away from Earth.
why is red shift called so
The highest wavelength lights are red. The lights we see from space tends to move towards the red end of the spectrum because their observed wavelength is getting higher and higher(and frequency is therefore lower).
what idea does the red shift effect support
The universe is expanding
The Big Bang Theory
- At the beginning of the universe, scientists think that all matter was condensed into a tiny area. This area was very hot and very dense.
- At some point, there was a big bang, when the hot, dense area of matter exploded. The matter all began to move away from each other, meaning that the ‘universe’ at that point was expanding.
- From our observations of the wavelengths of light from distant galaxies (red-shift), we know that the universe is still expanding today. This provides evidence to support the Big Bang theory.
what was the universe like when the big bang happened
a singularity, infinitely dense and hot
how does red shift provide evidence for the big bang theory
after 10^-35s after the big bang, the universe started expanding rapidly, including a phase of incredible acceleration known as inflation. The matter all began to move away from each other, meaning that the ‘universe’ at that point was expanding.
From our observations of the wavelengths of light from distant galaxies (red-shift), we know that the universe is still expanding today. This provides evidence to support the Big Bang theory.
what happened within the first second of the big bang
universe expanded rapidly, universe full of gamma photons, quarks gain mass through mechanisms involving the higgs boson, quarks then combined to form hadrons, matter was then created. Temperature started at 10^28K and reached 10^-9K, when matter was created
what happened 100 seconds after the big bang
protons and neutrons fused to form deuterium & helium nuclei, with small traces of lithium & beryllium, 25% of matter is helium nuclei ( primordial helium).
380,000 years after the big bang
first atoms formed, em radiation from this can be detected as microwave background radiation
evidence for the expansion of the universe
The speed of a galaxy will be determined by its distance from us. The closer a galaxy is to us, the slower it will move. The further away it is, the faster it will move. Galaxies that are furthest away from us will move the fastest. Since they are moving, space (and therefore the universe) must be expanding.
how does cosmic microwave background radiation (CMBR) give evidence for the big bang theory
the big bang theory predicts that Initial Big Bang heat should now be thinly spread across the whole Universe, and astronomers have discovered that CMBR is everywhere at a temperature of about -270°C
how much of the universe do we estimate that we understand.
5%
name of energy and matter humans dont understand
dark energy and dark matter
supernova theory supporting dark energy
astronomical observations of supernova have suggested that distant galaxies are moving away increasingly faster. The expansion of the Universe appears to be accelerating. Scientists do not entirely understand this but think it would require an energy source which is “dark energy.”
what do we know about dark energy
The nature of dark energy is still a complete mystery, but it is thought to cause the Universe to expand faster all the time. Astronomers have calculated that to make the Universe accelerate as observed, dark energy must account for 68 per cent of the Universe.
galaxies rotation dark matter theory
galaxies seem to rotate too quickly for the mass of their stars. This suggests that there is mass in the Universe that is invisible to the instruments used by scientists. Scientists only know it is there because it has gravity that affects objects nearby. This unknown material has been called dark matter. Astronomers have calculated that 27 per cent of the Universe must be made of this dark matter.
motion dark matter theory
most of the matter we can see is observed near the centre of galaxies, however the laws of motion require the matter to not be concentrated in the centre so there should be another type of matter we cant see - “dark matter”.
