Unit 7 - Astronomy Flashcards
What was Ptolemy’s idea?
That Earth was in the centre and everything orbited it (geocentric model)
What was Copernicus’ idea?
That the sun was at the centre of the solar system (heliocentric model)
What are comets mostly made from
Ice
What does our current solar system model show?
8 planets, 5 dwarf planets, thousands of comets and millions of asteroids
What did the invention of photography allow astronomers
To make more detailed observations and measurements
What are computers used for by astronomers
To analyse the information from telescopes
Why do telescopes in orbit give clearer images?
Clouds and dust in the air do not interfere with the image
Why must telescopes deleting certain electromagnetic waves be places in orbit
The atmosphere absorbs some of the radiation they are designed to detect
What is weight
The force of gravity acting on you
What is the word equation for weight
Weight = mass x gfs
What makes surface gravity greater
A larger mass but smaller radius (denser)
What are artificial satellites used for
Communications and to observe the earth
Give 3 uses of satellites
Weather
Broadcasting
Photographs
What are the 3 types of orbits satellites can be put into
Geostationary (over the same point Polar orbit (over the Poles) Low earth
Why does an orbiting body have a constantly changing velocity
The direction is changing
Is the gravitational force Ona satellite in low orbit strong or weak
Strong
What will happen to the earth when our sun becomes a red giant?
It will get swallowed up
What is a nebula?
A cloud of dust and gases (mainly hydrogen)
How is a protostar formed from a nebula?
The material is pulled together by its own gravity, the hydrogen becomes hotter and starts to glow, as more mass is pulled, the gravity gets stronger and it gets hotter.
What happens during the main sequence of a star
The high pressures force the hydrogen nuclei to fuse spit form helium. Fusion reactions release a lot of energy.
What form of energy is released from fusion?
Electromagnetic radiation
What stops the start in main sequence from collapsing in on itself
The pressure from the hot gases balance the compression of gravity
How does a start become a red giant?
When most of the hydrogen has fused into helium, the core is not hot enough to withstand the gravity and collapses, th per outer layer expands to form the red giant
What stage is our current star in?
Main sequence
How long does a star remain a red giant
1 billion years
How is a white dwarf formed?
Fusion continues forming heavier elements, the star throws of a shell of gas and the rest of the star is pulled together by gravity and collapses to form a white dwarf.
How does a white dwarf become a black dwarf
No fusion happens so the star begins to cool.
What is the life cycle of stars like ours (6)
Nebula, protostar, main sequence, red giant, shell of gas, white dwarf
How is a red supergiant formed
If there is more mass, fusion of hydrogen happens much quicker
How does a supernova occur?
At the end of a red supergiant, it rapidly starts to co,,also and then explodes
How is a black hole formed
If the mass of the star is 4 times our star, gravity pulled the remains together, light cannot escape from the pull of gravity
How is a neutron start formed
If the star isn’t massive enough, gravity pulls it together to form a small, very dense star
What is the life cycle of a massive star? (6)
Nebula, protostar, main sequence, red supergiant, supernova, blackhole/ neutron star.
What is the Doppler effect
When the pitch of sounds change due to moving or becoming closer to you
How does the Doppler effect occur?
The sound waves behind the source become ‘stretched’ making the wavelength longer and the frequency lower so the pitch is lower. It is opposite if you are in front of the sound source
What must be happening for the Doppler effect to take place
If the observer is stationary
What is red-shift
When the patterns of the dark lines on a visible spectrum have been shifted to the red end of the spectrum due to the object moving away
When does red - shift occur
When an object is travelling further away from the observer
When does blue - shift occur?
When the object is moving closer to the observer
What does red-shift show about the universe
That it is expanding
Describe the speed of a large red-shift
Faster
What does the Big Band theory explain about the origin of the universe?
All matter started as a tiny point of concentrated energy, the universe expanded from this point and is still expanding, the gravity clumped matter to form stars
How is matter dispersed according to the Big Bang theory as it expands
Spreading away as it expands
What does the Steady State theory say
The universe has always existed, it is expanding
What is the main difference between the Steady State theory and the Big Bang theory
The BBt says matter is not created, the SSt theory says matter is created
Why is the energy released form the Big Band theory only detected as microwave radiation
The universe is expanding so the wavelengths are increasing
What is cosmic microwave background radiation?
The radiation that is detected from the universe
How was cosmic microwave background radiation discovered?
2 radio astronomers detected the microwave signals, thought it was a fault in their equipment but realised that they were real.
What evidence supports both the SSt and the BBt?
The universe is expanding due to red-shift
Why is the Big Bang theory preferred over the Steady State theory?
It can support the evidence of the CMB radiation
