Topic 7 Astronomy

Question 1

1 What is the nearest star to the Earth?

Answer 1

the Sun

Question 2

2 Name two types of body found in the Solar System.

Answer 2

two of: the Sun/star, planets, dwarf planets, asteroids, comets, moons/satellites

Question 3

3 What is the name for the path that a planet follows around the Sun?

Answer 3

orbit

Question 4

4 How many planets are there in the Solar System?

Answer 4

eight

Question 5

5 Apart from Earth, name two other planets in the Solar System.

Answer 5

any from Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune

Question 6

6 What is a moon?

Answer 6

a natural body that orbits a planet

Question 7

7 Name one type of body, other than a planet, that orbits the Sun.

Answer 7

comet, asteroid or dwarf planet

Question 8

8 Why can we see planets in the night sky?

Answer 8

They reflect light from the Sun.

Question 9

9 What shape is the orbit of a planet around the Sun?

Answer 9

elliptical, but almost circular

Question 10

10 Name an instrument that can be used to study the stars and planets from the Earth.

Answer 10

telescope

Question 11

11 What is the geocentric model of the Solar System?

Answer 11

the idea that the Sun and all the planets are moving around the Earth

Question 12

12 Who suggested the geocentric model?

Answer 12

Ptolemy

Question 13

13 What is the heliocentric model?

Answer 13

the idea that everything in the Solar System orbits the Sun

Question 14

14 Who is best known for suggesting the heliocentric model?

Answer 14

Copernicus

Question 15

15 Name the planets in order, starting with the one nearest the Sun.

Answer 15

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Question 16

16 Put these in order of size, starting with the smallest: dwarf planet, planet, asteroid

Answer 16

asteroid, dwarf planet, planet

Question 17

17 Why are some telescopes put onto satellites?

Answer 17

because the Earth’s atmosphere absorbs some wavelengths of EM radiation / to put them above the clouds or dust in atmosphere

Question 18

18 Name one factor that the weight of an object depends on.

Answer 18

mass or gravitational field strength

Question 19

19 What is an artificial satellite?

Answer 19

something made by humans in orbit around a planet or moon

Question 20

20 What shape is the orbit of a comet?

Answer 20

highly elliptical

Question 21

21 What does g stand for?

Answer 21

gravitational field strength

Question 22

22 What are the units for g?

Answer 22

N/kg

Question 23

23 Name two factors that affect the weight of an object.

Answer 23

mass and gravitational field strength

Question 24

24 Name two factors that affect the surface gravity of a planet.

Answer 24

mass and radius

Question 25

25 How does mass affect g?

Answer 25

greater mass, greater g

Question 26

26 What happens if a satellite speeds up in its orbit?

Answer 26

moves to a higher orbit

Question 27

27 Why is the velocity of a satellite always changing?

Answer 27

velocity is a vector

Question 28

28 Name a type of star

Answer 28

any from main sequence star, red giant, red supergiant, white/red/brown/black dwarf, black hole, neutron star, etc.

Question 29

29 What reactions happen inside the Sun?

Answer 29

nuclear / fusion reactions

Question 30

30 What is the main element that is used in the fusion reactions in the Sun?

Answer 30

hydrogen

Question 31

31 What is a nebula?

Answer 31

a cloud of dust and gas

Question 32

32 What is a protostar?

Answer 32

a contracting cloud of gas that is heating up

Question 33

33 At what stage in its life cycle is the Sun?

Answer 33

main sequence

Question 34

34 What is the next stage in the Sun's life cycle?

Answer 34

red giant

Question 35

35 How will the Sun end its life cycle?

Answer 35

white dwarf

Question 36

36 What factor decides whether a star follows the same life cycle as the Sun?

Answer 36

its mass

Question 37

37 For a high-mass star, what is formed after a supernova?

Answer 37

black hole or neutron star

Question 38

38 What does the pitch of a sound describe?

Answer 38

how high or low the sound is

Question 39

39 What determines the pitch of a sound?

Answer 39

frequency/wavelength of the waves

Question 40

40 How does a sound change if the object is moving towards you?

Answer 40

higher pitch / shorter wavelength / higher frequency

Question 41

41 What happens to the pitch of a sound if the source is moving away from you?

Answer 41

gets lower

Question 42

42 What is the name for this effect?

Answer 42

Doppler effect

Question 43

43 What happens to the frequency of light waves from a star moving towards us?

Answer 43

gets higher

Question 44

44 What happens to the wavelength of light from a star moving away from us?

Answer 44

gets longer

Question 45

45 What is the name for the change in wavelength in the light from a star moving away from us?

Answer 45

red-shift

Question 46

46 How does the red-shift of a galaxy depend on its distance from us?

Answer 46

More distant galaxies have greater red-shifts.

Question 47

47 What does the red-shift of galaxies tell us?

Answer 47

The Universe is expanding.

Question 48

48 Name one theory about the origin of the Universe.

Answer 48

Big Bang or Steady State

Question 49

49 Which theory explains the expansion of the Universe?

Answer 49

both of them

Question 50

50 Which theory is the one accepted by scientists today?

Answer 50

Big Bang

Question 51

What is the pneumonic to remember the order of the planets from the sun?

Answer 51

``` My Very Energetic Mother Just Swam Under a Narwhal. ```

Question 52

What is a comet?

Answer 52

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.

Question 53

Which is true about polar orbits?

Answer 53

Polar orbits have a smaller radius than geostationary orbits, so are lower not higher.

Question 54

What is red shift?

Answer 54

Red shift is the increase in wavelength of light from a distant galaxy moving away from Earth.

Question 55

How many galaxies show a red shift?

Answer 55

Nearly all galaxies.

Question 56

What does a larger red shift indicate?

Answer 56

Red shift is larger if the galaxy is moving away faster.

Question 57

More distant galaxies show more red shift. Which major theory does this support?

Answer 57

This red shift evidence supports the Big Bang theory. Galaxy clusters can be observed directly.

Question 58

Why do scientists believe in the Big Bang theory?

Answer 58

The Big Bang theory's predictions are supported by observations so scientists believe it. Supernova explosions are not like the Big Bang.

Question 59

What does the Steady State theory suggest?

Answer 59

The Steady State theory states that the Universe has always existed and is expanding, creating matter all the time.

Question 60

What is NOT a problem for telescopes on satellites?

Answer 60

Satellite-based telescopes do not suffer bad weather. They are above the atmosphere so could detect all EM waves.

Question 61

What is a main sequence star?

Answer 61

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.

Question 62

How old is the sun?

Answer 62

The Sun (and Solar System) formed about 4.6 billion years ago. The Big Bang occurred about 13.8 billion years ago.

Question 63

What did Edwin Hubble conclude about the Universe in 1925?

Answer 63

it is expanding

Question 64

what happens to the amount of red-shift the further away the galaxy is?

Answer 64

Larger/more red-shift

Question 65

what is the relationship between red-shift and the velocity of the source?

Answer 65

More red-shift = higher velocity

Question 66

What is the doppler effect?

Answer 66

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.

Question 67

What type of waves are effected by the doppler effect?

Answer 67

All types of waves.

Question 68

what happens if the radius of an object in orbit decreases?

Answer 68

speed increases.

Question 69

In our solar system, the only star is the Sun. Briefly describe the Sun's formation.

Answer 69

1. The Sun started as a nebula (a cloud of dust). 2. Gravity pulled the dust and particles together. 3. 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. 4. This process let out a lot of energy which brought it into equilibrium with the gravitational energy. 5. This state of equilibrium means that the Sun is now in the main sequence stage.

Question 70

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.

Answer 70

1. 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. 2. 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. 3. This expansion provides evidence for the Big Bang theory. 4. Based on the relative speed of different galaxies and how far away they are, we can determine the age of the universe.