P8

Question 1

What is the order of the planets?

Answer 1

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

Question 2

What is Mercury, Venus, Earth and Mars all examples of?

Answer 2

Relatively small, rocky planets

Question 3

What is beyond the orbit of Neptune?

Answer 3

A number of dwarf planets including Pluto

Question 4

What are three other objects found in space? (which are not planets or stars?

Answer 4

Moons, asteroids, comets

Question 5

What are moons?

Answer 5

Natural satellites which orbit planets

Question 6

What is our solar system part of?

Answer 6

The milky way galaxy

Question 7

What is a galaxy?

Answer 7

A massive group of stars

Question 8

How many stars does the milky way contain?

Answer 8

Hundreds of Billions

Question 9

How many galaxies does the universe contain?

Answer 9

Hundreds of Billions

Question 10

What are the steps that form a star?

Answer 10

1- A nebula collapses due to gravity forming a protostar
2- the temperature rises to millions of degrees celcius due to the dust particles moving faster
3- Nuclear fusion releases a huge amount of energy which is equal to the force of the gravity causing the star to collapse therefore the star is at equilibrium

Question 11

What is a nebula?

Answer 11

a cloud of dust and gas mainly consisting of hydrogen gas

Question 12

What is a protostar?

Answer 12

a collapsing nebula

Question 13

What is nuclear fusion?

Answer 13

When the temperature of the protostar gets high enough, the hydrogen nuclei join together to form hydrogen

Question 14

What does it mean when we say a star is at equilibrium?

Answer 14

There are 2 opposing forces in a star. Gravity acts inwards making the star collapse and the energy from nuclear fusion creates a force acting outwards to make the star expand. When these 2 forces are equal the star is at equilibrium.

Question 15

What is the only way elements heavier than iron can be produced?

Answer 15

In a supernova

Question 16

What happens to a star which is a similar size to our sun?

Answer 16

• hydrogen in the star begins to run out meaning the star is no longer at equilibrium
• star collapses inwards increasing the temperature
• helium nuclei fuse together creating heavier elements
• star expands to form a red giant
• when red giant stops fusing helium the star shrinks to form a white dwarf
• white dwarf cools down as it’s no longer carrying out fusion
• white dwarf stops releasing energy and forms a black dwarf

Question 17

What happens to a star which is bigger than our sun?

Answer 17

-hydrogen runs out, star is not at equilibrium
- stars collapses inwards increasing temperature
- helium nuclei fuse together creating heavier elements
- star expands to form a red giant
- when red giant stops carrying out nuclear fusion the star explodes (supernova)
- temperature of supernova is high enough to produce elements heavier than iron which are distributed throughout the universe
- remains of the star either form a neutron star or a black hole

Question 18

What does a neutron star consist of?

Answer 18

neutrons densely packed together

Question 19

What does a black hole have?

Answer 19

such a large gravity that not even light can escape

Question 20

What is the shape of the Earths orbit?

Answer 20

Virtually circular

Question 21

What orbits the sun?

Answer 21

Planets

Question 22

What holds objects in their orbits?

Answer 22

The force of gravity

Question 23

What is the name of man-made satellite?

Answer 23

Artificial satellite

Question 24

How often do geostationary satellites orbit the Earth and what does this mean?

Answer 24

They orbit once every 24 hours meaning they always point to the same part of the Earth

Question 25

In the case of circular orbits what does the force of gravity lead to?

Answer 25

A change in velocity but not a change in speed

Question 26

What must change if the speed of an object in space changes?

Answer 26

the radius of the orbit

Question 27

If the speed of an object in space increases what happens to the radius and why does this happen?

Answer 27

The radius decreases so the object remains in a stable orbit as at higher speeds the object needs a greater force of gravity to prevent it from flying out into space.

Question 28

What did astronomers in the 1900's discover from studying the light emitted from different galaxies?

Answer 28

That the light from distant galaxies has an increased wavelength compared to light from closer galaxies

Question 29

What is red-shift?

Answer 29

When the black lines have shifted slightly towards the red end of the spectrum

Question 30

How does red-shift provide evidence that the universe is expanding?

Answer 30

red-shift tells us that galaxies are moving away from each other and that galaxies that are further away have a larger red-shift meaning they are moving faster than galaxies which are closer

Question 31

What is the big bang theory?

Answer 31

Scientists believe that the universe began from an extremely hot and dense, very small region which expanded into the universe today

Question 32

What did scientists observe around 1998 which disproved the assumption that the expansion of the universe would gradually slow down due to gravity?

Answer 32

Observations of supernova show that the rate of expansion is increasing

Question 33

What could possibly explain why the expansion of the universe is speeding up?

Answer 33

The universe contains matter and energy we cannot detect called dark matter and dark energy