Space

Question 1

What is the order of the planets?

Answer 1

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

Question 2

What is a nebula?

Answer 2

A cloud of gas and dust

Question 3

What is a satellite?

Answer 3

An object that orbits a more massive object

Question 4

What are natural satellites?

Answer 4

Moons

Question 5

What are artificial satellites?

Answer 5

Man made satellites for communication, weather, military purposes and navigation

Question 6

What is an orbit?

Answer 6

The path of a celestial body or an artificial satellite as it revolves around another body; it is one complete revolution of such a body around such a path

Question 7

How do orbits work?

Answer 7

The force of gravity from the sun pulls the earth towards the centre of the sun, providing a centripetal force - the direction of the earth’s velocity is always perpendicular to the centripetal force resulting in a resultant force of the earth’s orbit

Question 8

Why is no work done to an object in orbit?

Answer 8

Because the distance moved by the object and direction of the force are always perpendicular to each other and equal

Question 9

What are geostationary orbits and what satellites are placed in these orbits?

Answer 9

Geostationary orbits mean that a satellite will appear to ‘sit still’ above a particular position of the earth’s surface as it has the same time period as the earth’s rotation
Communication satellites are placed in this orbit

Question 10

What is a polar orbit and what satellites are placed in these orbits?

Answer 10

When we need an object to ‘move’ and cover distance around the earth’s surface we can use a polar orbit where they orbit vertically, orbiting over the north and south poles three or four times a day
Weather and spying satellites are placed in this orbit

Question 11

What happens if a satellite in orbit is too slow?

Answer 11

It will eventually fall to the earth’s surface

Question 12

What happens if a satellite in orbit is too fast?

Answer 12

It will continue along its fixed path as it travels around the earth and then leave the earth’s orbit

Question 13

When will a satellite need a lower speed?

Answer 13

If the satellite is further away from the object it’s orbiting then it needs a lower speed to stay in circular orbit because there is a lesser force of gravity

Question 14

When will a satellite need a greater speed?

Answer 14

If the satellite is closer to the object it’s orbiting it must have a greater speed to match the greater force of gravity and stay in orbit

Question 15

Why might the orbit of a satellite become too slow?

Answer 15

Because it was too close to the earth and gradually lost speed due to atmospheric drag before falling towards earth

Question 16

How are stars formed?

Answer 16

1) Starts as a massive cloud of dust and gas in space called a nebula
2) Gravity then pulls the gas and dust together to form protostars and the leftover gas and dust slowly clumps together due to gravity to form the planets
3) As the protostar becomes denser it gets very hot, causing lighter nuclei to join together and energy is released from nuclear fusion and it gets even hotter
4) After this comes the main sequence or the stable stage of a star in which it enters a long period where the outward force created by nuclear fusion balances the inward force of gravity

Question 17

When does the main sequence of a star end?

Answer 17

When the star has run out of hydrogen

Question 18

What does the length of the main sequence depend on and why?

Answer 18

The mass of the star; the larger the mass, the shorter the main sequence period because there are more hydrogen molecules available for nuclear fusion and it will run out faster

Question 19

What is the life cycle of red giant stars?

Answer 19

1) When all of the helium in the core is converted into carbon, the star expands and then collapses to form a white dwarf
2) The outer layers are blown off as a planetary nebula
3) After cooling, the star becomes a black dwarf

Question 20

What is the life cycle of red super giant stars?

Answer 20

1) Once fusion stops, the star expands and then the core collapses inwards, the resulting shock wave forming a supernova which becomes another nebula
2) The stars’ core then compresses and becomes a neutron star which is an extremely dense object composed only of neutrons (one teaspoon of a neutron star would weigh 10 billion tons)
3) If the star is big enough, it will form a black hole rather than a neutron star

Question 21

What elements are formed from fusion in red super giants?

Answer 21

Heavy elements up to iron are formed from fusion in red super giants, that’s why they become so large

Question 22

What is a black hole?

Answer 22

A super dense point in space with an immense gravitational force - its attraction is so strong that not even light can escape from it, hence the name

Question 23

What is the doppler effect?

Answer 23

The apparent change in wavelength and frequency of a wave due to the motion of the source

Question 24

What is blue shift?

Answer 24

If the source of the wave is moving towards the observer then the wavelength appears to decrease and the frequency increases (makes a higher pitched sound)

Question 25

What is red shift?

Answer 25

If the source of the wave is moving away from the observer then the wavelength appears to increase and the frequency decreases (makes a lower pitched sound)

Question 26

What does hubble’s law state?

Answer 26

The further away the galaxy, the larger the red shift

Question 27

What can red shift tell us about the universe?

Answer 27

There is an increase in the wavelength of light from most distant galaxies and they are shifted towards the red part of the spectrum; this means that the galaxies are moving away from us (receding) and the universe is expanding

Question 28

How old is the universe and how do we know?

Answer 28

The furthest galaxies are 14 billion light years away which is the approximate age of the universe