Space Physics Flashcards
Name the planets in order
- Sun
- Mercury
- Venus
- Earth
- Mars
- Saturn
- Uranus
- Neptune
Name the rocky planets
Mercury, Venus, Earth and Mars
Which planets are the larger planets?
Jupiter, Saturn, Uranus and Neptune
What comes after Neptune?
Dwarf planets like Pluto
Name other objects in the solar system
Moons
asteroids
comets
What are moons?
Natural satellites which orbit planets,
most planets have at least 1 but some have more
What is the solar system?
small part of the Milky Way galaxy
Galaxy
massive group of stars
How do stars form?
- From clouds of dust and gas - a nebula
- Gas is mainly Hydrogen in a nebula
- Gravity causes cloud of dust and gas to collapse
- As dust particles move faster, temp rises to millions of degrees celcius
- This is called a protostar
- If temp of protostar is high enough, hydrogen nuclei join together to form helium
- This is nuclear fusion
- Protostar has turned into a star
- Nuclear fusion releasing lots of energy
- Star is in equilibrium with gravity thats acting inwards - causes star to collapse (there are 2 opposing forces) and NF which acts outwards causing star to expand
- Both forces are balanced
- At this point, it is a main-sequence star
- What happens next depends on the size of the star
What is a nebula
cloud of dust and gas which is mainly hdyrogen
What does gravity cause the stars to do?
collapse
What does nuclear fusion cause the stars to do?
expand
What is a protostar?
- Formed by a nebula experiencing gravity which causes it to collapse
- Lots of particles moving quickly which causes a very high temp
What causes a protostar to turn into a star?
- If the temp is high enough, the hydrgoen nuclei will do nuclear fusion and join together to form helium
What happens to the main sequence star if its about the same size as our Sun/ small/ medium?
- Hydrogen in star begins to run out
- This point, outward force due to fusion energy is less than inward force due to gravity
- Causes star to collapse inwards
- Temp increases due ot collapse
- Helium nuclei fuse together to create heavier elements
- This makes expands to make a red giant
- At some point, red giant stops fusing helium
- Star shrinks = white dwarf
- Since its not carrying out fusion it cools down and stops releasing energy = black dwarf
What happens to the main sequence star if its bigger than our Sun?
- Red super giant shine brightly again - more nuclear fusion
- They explode = supernova
- forms elements heavier than iron due to the temp high that are ejected across the universe
- Supernova condenses into a neutron if star was big
- Or black hole if star was massive
What is a neutron star?
- Formed by a supernove if star was big
- Neutrons densely packed together
What is a black hole?
Lots of gravity that light cant escape
How does the Earth orbit the Sun?
In a circular orbit but striclty speaking scientists say they orbit as a elliptical orbit
What causes the Earth to be held in its orbit?
Force of gravity acting between sun and earth
How often do geostationary satellites orbit?
once every 24 hrs, this means they always point to the same part of the earth, however other artifical satellites orbit more freq
In circular orbits, what does the force of gravity lead to?
A change in velocity (speed w/ direction) but not in speed
If the satellite speed changes what also changes?
the radius of the orbit
If speed of satellite increases, what happens to radius? Why?
- radius of orbit decreases
- Because at a high speed, satellite needs greater force of gravity to prevent it flying off into space
- by moving closer, gf is greater and satellite remains in a stable orbit
What did scientists see in 1900 when looking at light emitted from diff galaxies?
- Light from v distant galaxies has an increased wavelength comapred to light from closer galaxies
What do nearby galaxies have and what does it mean?
- small redshift
- they are moving away
What do more distant galaxies have and what does it mean?
- larger red shift
- moving away faster
What do very distant galaxies have and what does it mean?
- very large redshift
- moving away v fast
Evidence for universe is expanding?
Distant galaxies are moving faster than nearby galaxies = expanding
2 types of satelites and explain what they are
- Natural - not man made
- Artificial - man made, communication, orbiting telescopes
What are asteroids
- made mostly of rock and metal
- found in asteroid belt (between mars and jupiter)
what are comets
- ice and dust
- have more of a elliptical orbit
- outskirts of solar system
What holds together the stars in a galaxy
gravity
What changes may happen in a protostar as it grows in size and attracts more particles?
- increase in temp
- increase in density
- nuclear fusion could intiate
What does a change in velocity mean in orbits?
accelerating
What is the asteroid belt and which 2 planets ist it found between?
- region in solar system that contains millions of asteroids
- Mars and Jupiter
As a protostar grows and attracts more particles from the surronding nebula, what changes happen?
- temp increases
- becomes more denser
- nuclear fusion could intiate
What allows for a long stable period for the main sequence star?
When the outward pressure caused by nuclear fusion is perfectly balanced with inward pressure caused by gravity
What law is applicable to how orbits at a certain velocity
- Newtons 1st Law
- continue to travel at that velocity unless acted upon by a resultant force
What is required for the object to stay in orbit?
magnitude of the velocity must increase
Why does red shift happen?
- Because light emitted by an object moving away from us will be stretched
- stretching = lights wavelength to increase
- faster an object moves away from us - larger red shift
- It is the space between the galaxy and Earth thats increasing, not the galaxy moving
Big Bang Theory
- Universe began from a very small region that was extremely hot and dense
- Giant explosion caused universe to expand
- still much about universe thats not understood like dark energy and dark mass
Since 1998 onwards, what did observations of supernovae suggest?
distance galaxies are receding ever faster
What is CMBR?
- (Cosmic microwave background radiation) is em radiation thats observed in all direction
- Initially, radiation from bb was hot
- as universe expanded and cooled, the background radiation has dropped in freuqency
Red shift equation
diff between observed wavelength and original wavelength
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original wavelength of light
= recessional velocity of galaxy
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speed of light in a vacuum, 300,000,000 m/s
Which side of the absorption spectra has the longer wavelength? Shortest?
- longest = left side thats red
- shortest = right side = violet
Describe the light absoroption spectra of the Sun
- star emits light of all wavelengths
- However, some wavelengths of light are absorbed by chemicals in sun’s atmosphere
- light that reaches earth has some wavelengths of light missing
What provides evidence for Big Bang?
red shift
What side has the absoption spectra pattern from distant galaxies shifted to?
red side of spectra
Strengths and weaknesses of using a balloon to represent expanding universe
+ = As the balloon expands the dots get further apart, which represents the galaxies moving apart
- = The dots are only on the surface of the balloon, whereas galaxies are throughout the universe
- = There is a limit to how far the balloon can expand before it bursts
Why may scientists start to believe in another theory instead of the old one?
new evidence that cant be explained by old theory
What info can we get if we measure the size of the red-shift the galaxy produces?
- Distance from Earth
- Speed its moving
Explain how the scientific evidence for the “big bang” theory of the origin of the Universe
- galaxies show a red-shift
- but more distant galaxies shower bigger red shift
- Universe is expanding
- but more distant galaxies moving away faster
- so all Universe once in one place
When are elements heavier than iron produced?
in a supernova
2 things a supernova can turn into
- neutron star
- black hole
