8 Space

Question 1

What is a light-year?

Answer 1

A unit of distance for astronomical scales. The distance light can travel in one earth year.

Question 2

How many stars are in our solar system?

Answer 2

One - the sun

Question 3

Name the planets in our Solar System in order of distance from the sun.

Answer 3

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

Question 4

What is a planet?

Answer 4

A non-luminous, spherical object that orbits a star. It must dominate its orbit.

Question 5

What is a moon?

Answer 5

A non-luminous, natural object that orbits a planet.

Question 6

What is a galaxy?

Answer 6

A large collection of dust, gas and stars (each a possible planetary system of its own) held together by gravity.

Question 7

What type of object is Pluto?

Answer 7

Dwarf planet

Question 8

What is a ‘dwarf planet’?

Answer 8

A planet-like object in space that orbits a star but doesn’t match all the rules of being a planet

Question 9

What is the name of our galaxy?

Answer 9

Milky Way

Question 10

What is found in the spaces between astronomical objects (such as planets, moons, asteroids)?

Answer 10

There is a small amount of dust but there?s no air (we think of it as a vacuum), so sound can?t travel, but there is still gravity due to all of the masses nearby.

Question 11

How was the Sun formed?

Answer 11

From clouds of dust and gas drawn together by gravity, which caused fusion reactions to occur.

Question 12

What is a nebula?

Answer 12

A cloud of dust and gas in space

Question 13

What is a protostar?

Answer 13

The earliest stage in the life cycle of a star. Formed when the force of gravity causes a nebula to collapse. The increased temperature and pressure allows fusion to begin.

Question 14

What is a main sequence star?

Answer 14

A star during the main part of its lifecycle. The radiation pressure outwards from nuclear fusion balances the force of gravity inwards.

Question 15

What is a red giant?

Answer 15

A star, about the same size as our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium

Question 16

What is a red supergiant?

Answer 16

A star, much larger than our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium

Question 17

What is a white dwarf?

Answer 17

The hot, dense solid core of a red giant once it has ejected its outer layer as a planetary nebula.

Question 18

What is a black dwarf?

Answer 18

A white dwarf that has cooled sufficiently that it no longer emits significant heat or light.

Question 19

What is a supernova?

Answer 19

An explosion produced when the core of a red supergiant collapses. Elements heavier than iron are formed and ejected into space.

Question 20

What is a neutron star?

Answer 20

The core of a red supergiant that has collapsed but can still be seen

Question 21

What is a black hole ?

Answer 21

The core of a red supergiant that has collapsed. These are formed if the remaining core has a mass of more than 3 times the mass of the Sun. It is so dense that light can not escape it.

Question 22

When the temperature within a protostar gets high enough, what process can begin?

Answer 22

Nuclear fusion (of Hydrogen into Helium)

Question 23

What force brings the dust and gas inside a nebula together to form a star?

Answer 23

Gravitational force

Question 24

Describe what happens to stars the size of the sun or smaller after the main cycle

Answer 24

Hydrogen runs out, Hydrogen fusion stops, Helium nuclei fuse to form larger nuclei (up to iron), star expands to be become red giant, eventually outer layers drift away leaving a white dwarf, then black dwarf

Question 25

Describe what happens to stars much larger the sun after the main cycle

Answer 25

Hydrogen runs out, Hydrogen fusion stops, Helium nuclei fuse to form larger nuclei (up to iron), star expands to be become red giant, star collapses and explodes in supernova, forming heavier elements, leaving behind neutron star or black hole

Question 26

Why are main sequence stars in a state of equilibrium?

Answer 26

The force of gravity pulling the material inwards is balanced by an outwards force due radiation pressure (due to nuclear fusion).

Question 27

What is nuclear fusion?

Answer 27

When two small nuclei fuse together to form one larger nucleus, releasing energy in the reaction.

Question 28

How does nuclear fusion relate to stars?

Answer 28

The energy released by fusion reactions leads to the light that we see from stars. It causes an outward force that would cause the star to expand if it weren't in equilibrium with the force of the gravitational collapse.

Question 29

Which elements are produced in fusion in stars?

Answer 29

All naturally occurring elements, up to iron.

Question 30

Where are elements heavier than this produced?

Answer 30

In a supernova

Question 31

How are they distributed across the universe?

Answer 31

In the supernova explosion

Question 32

How do scientists know that our solar system is a second generation system ?

Answer 32

It contains heavy elements (such as gold, lead etc) which could only have been formed in a supernova and were then distributed throughout space by the explosion.

Question 33

What is the force that keeps planets and satellites in orbit?

Answer 33

Gravitational force

Question 34

What is an orbit?

Answer 34

The elliptical path that one object in space takes around another object. It is caused by the gravitational attraction between the two objects.

Question 35

What shape are the orbits of the planets?

Answer 35

Elliptical

Question 36

Name a natural satellite of the Earth.

Answer 36

The moon.

Question 37

What is an artificial satellite?

Answer 37

An object put into orbit around an astronomical object by humans e.g. the international space station around Earth, or the Pioneer probes around the Sun.

Question 38

In a circular orbit, how can there be changing velocity if the speed is constant?

Answer 38

As it is attracted by gravity, it is constantly changing direction to remain in the circular orbit. Velocity is a vector quantity.

Question 39

What quantity is defined as the rate of change of velocity?

Answer 39

Acceleration

Question 40

What is the name given to the resultant force that keeps objects moving in circles?

Answer 40

Centripetal force

Question 41

In what direction does a centripetal force act?

Answer 41

Towards the centre of the circle

Question 42

For a stable orbit, if the radius of the orbit decreases, what must happen to the speed?

Answer 42

The speed must increase.

Question 43

What factors affect the orbital speed of a satellite?

Answer 43

The mass of the planet or star, the mass of the satellite and the distance between the satellite and the object it is orbiting

Question 44

What is the Doppler Effect?

Answer 44

The observed frequency of waves emitted by a moving object appear changed.

Question 45

What is red-shift in observation of galaxies?

Answer 45

There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength.

Question 46

What is the Big Bang theory?

Answer 46

It suggests that the universe began from a very small region that was extremely hot and dense.

Question 47

How does observed red shift support the Big Bang theory?

Answer 47

It shows that the universe is expanding, so therefore must have once been much smaller.

Question 48

Since 1998 onwards, observations of supernovae suggest that?

Answer 48

The furthest away galaxies are moving away from us even faster.

Question 49

Explain what this image shows if the middle spectrum is from our Sun.

Answer 49

The top spectrum shows the absorption pattern (black lines) shifted towards the shorter, blue wavelengths of light - so this star must be moving towards us as the light is being compressed. The bottom spectrum shows the pattern shifted towards the longer, red wavelengths - so this star must be moving away from us as light is being stretched.

Question 50

Why is it important for scientists to observe?

Answer 50

Observations allow them to obtain data, which they use to arrive at theories like the Big Bang theory.

Question 51

There is still lots that scientists don't understand about the universe such as dark matter and dark energy. What are they an explanation for?

Answer 51

The expansion of the universe is slower than scientists would expect, so there must be something holding the universe together. We think about 68% of the universe is dark energy, 27% is dark matter and the rest is our known universe. We call them dark because we don't know much about them but believe that they must exist to make sense of observations.