TOPIC 7 Astronomy (Extra apart from School made) Flashcards
What is our solar system made of (name at least 3 features)?
- 8 planets (with some orbiting moons)
- The Sun
- 5 dwarf planets (eg: Pluto)
- Thousands of comets
- Millions of asteroids
What type of model did Ptolomy create about our Solar System?
Geocentric
All of the planets and the Sun were in small orbits around the Earth
What type of model did Copernicus create about the Solar System?
Heliocentric model- all of the planets orbit around the Sun.
What did Galileo discover and when?
By using a telescope, he discovered 4 of Jupiter’s moons.
By plotting their movement, he supported Copernicus (heliocentric model)
List 4 ways in which technology has helped scientists to discover more about the Solar System.
Any 4 from:
- Photographs have replaced drawings
- Computers can analyse photos and compare/analyse data
- Telescopes are both ground based and in orbit
- Telescopes in Space give clearer images + detect frequencies of EM waves absorbed by the atmosphere
- Modern telescopes detect a range of EM frequencies
What are the order of the planets in the Solar System? (Closest to further from Sun)
Mercury Venus Earth Mars Jupiter Saturn Neptune
What is the pneumonic to remember the order of the planets in the Solar System?
My Very Easy Method Just Speeds Up Naming
What is weight? Units?
The force of gravity acting on you.
Newtons, (N)
What affects the weight of an object on any body in space?
The greater the body in mass, the more weight
Why do some bodies have more gravitational field strength than others?
The more mass, the higher the gravitational field strength
Eg: the Earth has a larger GFS than the Moon because it has a larger mass
How is the weight of an object calculated?
mass (kg) x gravitational field strength (N/kg)
What is an orbit?
A regular and repeating path that one object in space takes around another object.
What is a satellite?
An object in orbit.
What are the two types of satellites, with examples?
1) Natural = eg: Moon to the Earth
2) Man-Made/Artifical = Hubble
What are the different types of orbit for artificial satellites?
- High elliptical orbit: communication in parts of the Earth, near the poles
- Circular geostationary orbit: remain over ONE POINT on Earth. Used for broadcasting and move at 3070m/s.
- Low Earth orbits-need little fuel and move at around 7500m/s
- Polar Orbit- Will eventually pass over all parts of the Earth
What kind of speed do satellites in a circular orbit move in?
Constant speed
Is the direction of a satellite in circular orbit changing or not?
What does this mean about the velocity?
Yes, the direction does change but the speed doesn’t. The gravitational force between the Earth and satellite is at right angles in the direction of movement.
The velocity is constantly changing.
How is the gravitational force in a lower orbit different to one in a higher orbit?
The gravitational force is greater in a lower orbit.
What happens to a low orbiting satellite, which isn’t moving at a high enough speed?
It will fall towards the Earth.
As it alls, it gains speed to stay in the much lower orbit.
If it falls low enough to the top of the atmosphere, contact with the air will slow it down and it’ll fall to Earth.
What type of star is the Sun?
What phase is the Sun in now?
Average star
The sun is a Main Sequence Star, which is undergoing nuclear fusion reactions from its core from hydrogen to helium
What are the different stages of an average star’s life cycle?
Nebula Protostar Main sequence star Red giant Shell of gas White dwarf
What are the stages of a massive star’s life cycle?
Nebula Protostar Massive main sequence star Red supergiant Supernova Neutron Star or Black Hole
Describe the stage of a star:
NEBULA
A cloud of dust and gas
Mainly hydrogen, small amounts of helium and dust
Contains GPE (gravitational potential energy)
Describe the stage of a star:
PROTOSTAR
Cloud of dust and gas (Nebula) contract and spiral in
Glowing
Hydrogen becomes hotter
Gravitational pull increases
Describe the stage of a star:
Main sequence star
Protostar continues to contract under its own gravity.
Hydrogen atoms accelerate and kinetic energy increases
Extra KE energy increase the temperature of hydrogen and atoms collide more frequently
FUSION BEGINS
Stable phase
Star is: contracting under gravity
expanding over heat. Balance for constant size
Do big star use up hydrogen quicker in fusion reactions?
What does this mean for the star?
Yes
They will survive for less time than a smaller star
Describe the average star’s lifecycle:
RED GIANT
Hydrogen from fusion runs out
Core collapses
Outer layers expand to form a RED GIANT STAR
Fusion of helium produces heavier elements than iron for about 1 billion years
Describe the average star’s life cycle:
WHITE DWARF
Outer shell of huge red giant star drifts awa
Star collapses
Forms a WHITE DWARF- hot and not fusing
Describe the average stra’s life cycle:
BLACK DWARF
Cool, dead star
Describe a massive star’s life cycle:
RED SUPERGIANT
Hydrogen from fusion runs out to form recsupethiants
Fusion helium —> heavier elements happens first few thousand years (up to iron)
Describe a massive star’s life cycle:
SUPERNOVA
Core collapses and outer layers explode of a red super giant to form a SUPERNOVA
A giant explosion
Describe the life cycle of a massive star:
NEUTRON STAR
Gravity pulls the remain sof a supernova Explosion to forma small dense neutron star, with NO FUSION.
Describe the life cycle of a massive star:
BLACK HOLE
If it’s is bigger than our Sun (and remains are more than the Dun), gravity pulls the remains together to for a BLACK HOLE.
Gravitational pull is strong that even light cannot escape it.
What is the Doppler Effect?
The apparent change in the frequency/wavelength of a wave, due to the relative motion of the source and the observer.
What happens when a noisy object is close to you:
- frequency
- wavelength
- frequency ⬆️
- wavelength ⬇️
What happens when a noisy object is far away from you:
- frequency
- wavelength
- frequency ⬇️
- wavelength ⬆️
What are asteroids and where are they found?
Lumps of rock and metal
Found in the asteroid belt
How do asteroids orbit?
They orbit around the Sun.
What are comets and where are they found?
Lumps of ice and dust
Orbit the Sun
What kind of orbits do comets have?
Highly elliptical orbits (stretched out circles)
Some travel from near to the sun to the outskirts of the Solar System
What type of orbit do artificial satellites have? What do they orbit?
They orbit the Earth in fairly circular orbits.
How do planets orbit the Sun (shape)?
Almost circular ELLIPTICAL orbits (just like the Earth and Moon)
What is centripetal force?
The force that keeps an object in circular orbit at a constant speed.
However, it is constantly accelerating (instantaneous velocity) towards what it is orbiting, keeping it in a circle.
How does the distance change how strong the GFS is?
What does this mean about the speed needed to stay in a closer orbit?
Closer, stronger gravitational field strength
In a closer orbit, the instantaneous speed must be larger to balance the force- moving FASTER.
Faster moving objects will move in a stable orbit with a ? radius than slower moving ones.
? = smaller
What is the Steady State Theory and what does it mean?
1) Universe has always existed as it is now and always will do
2) As the Universe expands, new matter is constantly being created
3) Density of the Universe stays roughly the same
4) NO BEGINNING OR END TO UNIVERSE
What is the Big Bang Theory and what does it say about our universe?
1) Initially, all the matter in the Universe occupied a very small space.
2) Small spec was very DENSE and hot
3) It then EXPLODED
4) Space started EXPANDING and it still is expanding
5) The Universe is 13.8 billion year old (finite age).
Which 2 ideas support the Big Bang Theory?
- Red-shift
- CMBR (Cosmic Microwave Background Radiation)
How does red-shift support the Big Bang Theory?
- Different elements absorb different frequencies of visible light
- From distant galaxies, we see light that is at slightly lower frequencies on the visible light spectrum - red-shift
- Measurements of the red-shift suggest that all distant gallons are moving away from us very quickly
- More distant aviary is- the greater the red-shift (increased wavelength)
- Distant goalies are moving a way faster- UNIVERSE IS EXPANDING
How does CMBR support the Big Bang Theory?
- Scientists have detected low freq. EM radiation coming from all parts of the Universe, mostly in the microwave part of the EM spectrum
- It shows that the Universe has a beginning unlike red-shift (expansion of Universe) because huge amounts of radiation were released at the beginning of the Universe and continue to increase in wavelength.
How can you improve the quality of an image using a telescope?
1) Increase the aperture (diameter of objective lens, where light enters).
2) Use a higher quality objective lens.
Why are telescopes on Earth not as good as telescopes in Space?
1) Light pollution (eg: from Street lights)- hard to pick up dark objects
2) Air pollution - reflects and absorbs light coming from space.
