Topic 7 Astronomy Flashcards
1 What is the nearest star to the Earth?
the Sun
2 Name two types of body found in the Solar System.
two of: the Sun/star, planets, dwarf planets, asteroids, comets, moons/satellites
3 What is the name for the path that a planet follows around the Sun?
orbit
4 How many planets are there in the Solar System?
eight
5 Apart from Earth, name two other planets in the Solar System.
any from Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune
6 What is a moon?
a natural body that orbits a planet
7 Name one type of body, other than a planet, that orbits the Sun.
comet, asteroid or dwarf planet
8 Why can we see planets in the night sky?
They reflect light from the Sun.
9 What shape is the orbit of a planet around the Sun?
elliptical, but almost circular
10 Name an instrument that can be used to study the stars and planets from the Earth.
telescope
11 What is the geocentric model of the Solar System?
the idea that the Sun and all the planets are moving around the Earth
12 Who suggested the geocentric model?
Ptolemy
13 What is the heliocentric model?
the idea that everything in the Solar System orbits the Sun
14 Who is best known for suggesting the heliocentric model?
Copernicus
15 Name the planets in order, starting with the one nearest the Sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
16 Put these in order of size, starting with the smallest: dwarf planet, planet, asteroid
asteroid, dwarf planet, planet
17 Why are some telescopes put onto satellites?
because the Earth’s atmosphere absorbs some wavelengths of EM radiation / to put them above the clouds or dust in atmosphere
18 Name one factor that the weight of an object depends on.
mass or gravitational field strength
19 What is an artificial satellite?
something made by humans in orbit around a planet or moon
20 What shape is the orbit of a comet?
highly elliptical
21 What does g stand for?
gravitational field strength
22 What are the units for g?
N/kg
23 Name two factors that affect the weight of an object.
mass and gravitational field strength
24 Name two factors that affect the surface gravity of a planet.
mass and radius
25 How does mass affect g?
greater mass, greater g
26 What happens if a satellite speeds up in its orbit?
moves to a higher orbit
27 Why is the velocity of a satellite always changing?
velocity is a vector
28 Name a type of star
any from main sequence star, red giant, red supergiant, white/red/brown/black dwarf, black hole, neutron star, etc.
29 What reactions happen inside the Sun?
nuclear / fusion reactions
30 What is the main element that is used in the fusion reactions in the Sun?
hydrogen
31 What is a nebula?
a cloud of dust and gas
32 What is a protostar?
a contracting cloud of gas that is heating up
33 At what stage in its life cycle is the Sun?
main sequence
34 What is the next stage in the Sun’s life cycle?
red giant
35 How will the Sun end its life cycle?
white dwarf
36 What factor decides whether a star follows the same life cycle as the Sun?
its mass
37 For a high-mass star, what is formed after a supernova?
black hole or neutron star
38 What does the pitch of a sound describe?
how high or low the sound is
39 What determines the pitch of a sound?
frequency/wavelength of the waves
40 How does a sound change if the object is moving towards you?
higher pitch / shorter wavelength / higher frequency
41 What happens to the pitch of a sound if the source is moving away from you?
gets lower
42 What is the name for this effect?
Doppler effect
43 What happens to the frequency of light waves from a star moving towards us?
gets higher
44 What happens to the wavelength of light from a star moving away from us?
gets longer
45 What is the name for the change in wavelength in the light from a star moving away from us?
red-shift
46 How does the red-shift of a galaxy depend on its distance from us?
More distant galaxies have greater red-shifts.
47 What does the red-shift of galaxies tell us?
The Universe is expanding.
48 Name one theory about the origin of the Universe.
Big Bang or Steady State
49 Which theory explains the expansion of the Universe?
both of them
50 Which theory is the one accepted by scientists today?
Big Bang
What is the pneumonic to remember the order of the planets from the sun?
My Very Energetic Mother Just Swam Under a Narwhal.
What is a comet?
A comet is made from rocky material, dust and ice, and orbits the Sun. An object that orbits the Earth would be a natural satellite.
Which is true about polar orbits?
Polar orbits have a smaller radius than geostationary orbits, so are lower not higher.
What is red shift?
Red shift is the increase in wavelength of light from a distant galaxy moving away from Earth.
How many galaxies show a red shift?
Nearly all galaxies.
What does a larger red shift indicate?
Red shift is larger if the galaxy is moving away faster.
More distant galaxies show more red shift. Which major theory does this support?
This red shift evidence supports the Big Bang theory. Galaxy clusters can be observed directly.
Why do scientists believe in the Big Bang theory?
The Big Bang theory’s predictions are supported by observations so scientists believe it. Supernova explosions are not like the Big Bang.
What does the Steady State theory suggest?
The Steady State theory states that the Universe has always existed and is expanding, creating matter all the time.
What is NOT a problem for telescopes on satellites?
Satellite-based telescopes do not suffer bad weather. They are above the atmosphere so could detect all EM waves.
What is a main sequence star?
A stable stage in the life cycle of a star. There is a balance between the outwards radiation and the force of gravity pulling inwards.
How old is the sun?
The Sun (and Solar System) formed about 4.6 billion years ago. The Big Bang occurred about 13.8 billion years ago.
What did Edwin Hubble conclude about the Universe in 1925?
it is expanding
what happens to the amount of red-shift the further away the galaxy is?
Larger/more red-shift
what is the relationship between red-shift and the velocity of the source?
More red-shift = higher velocity
What is the doppler effect?
The Doppler effect describes the phenomenon of the observed wavelength and frequency of waves changing when the source of the waves is moving with respect to an observer.
What type of waves are effected by the doppler effect?
All types of waves.
what happens if the radius of an object in orbit decreases?
speed increases.
In our solar system, the only star is the Sun.
Briefly describe the Sun’s formation.
- The Sun started as a nebula (a cloud of dust).
- Gravity pulled the dust and particles together.
- Gravity between the particles increased until it was strong enough to allow hydrogen gas to undergo nuclear fusion to make helium. This formed a protostar.
- This process let out a lot of energy which brought it into equilibrium with the gravitational energy.
- This state of equilibrium means that the Sun is now in the main sequence stage.
Astronomers make observations of distant galaxies using telescopes on the Earth. The information that they obtain can tell us much about the nature of those galaxies and our universe.
These observations have led to discoveries about the distances and speeds of the galaxies and how our universe began and grew.
Suggest how the observations made from Earth have changed our understanding of how our universe was formed and developed.
- Red shift is a phenomenon where light moving towards us will have its wavelength altered based on the speed at which the emitter is moving away from us.
- By judging the red shift of light from certain celestial objects, we can tell how fast they are receding. This provides evidence for the fact that the universe is expanding.
- This expansion provides evidence for the Big Bang theory.
- Based on the relative speed of different galaxies and how far away they are, we can determine the age of the universe.
