2.5 - Stars and planets

Question 1

In which galaxy is our solar system?

Answer 1

The Milky Way galaxy

Question 2

What does our solar system consists of?

Answer 2

Four inner rocky planets and four outer gas giant planets as well as an asteroid belt, containing thousands of huge rocks, dwarf planets and comets.

Question 3

What do the planets in our solar system orbit around and what type of body is it?

Answer 3

The planets orbit around the sun

The sun is a star

Question 4

What type of force pulled together the cloud of dust and gas to form the sun?

Answer 4

Gravitational force of attraction

Question 5

What is the order of the planets in our solar system?

Answer 5

My            - Mercury
Very         - Venus 
Easy         - Earth
Method    - Mars 
Just           - Jupiter
Speeds     - Saturn 
Up             - Uranus 
Naming    - Neptune

Question 6

The planets go around the Sun in slightly squashed circular elliptical orbits. What is an elliptical orbit?

Answer 6

An orbit that is the shape of an ellipse. An ellipse is similar to a slightly stretched circle

Question 7

What are comets?

Answer 7

A high speed ball of ice and rock which as it melts leaves a trial of dust and gas behind it

Question 8

What are asteroids?

Answer 8

Lumps of rock which orbit the sun in the asteroid belt

Question 9

How does a solar system form?

A dense hydrogen-rich cloud of ___ and ___ contracts under gravity. As the gas gets compressed, its temperature ________ and the dust cloud begins to spin. A ______ begins to form at the centre of this spinning dust cloud. _____ _____ starts, and a star is born. The planets begin to form from the swirling dust clouds around the star.

Answer 9

gas and dust
increases
protostar
nuclear fusion

Question 10

What word is used to describe a cloud of dust and gas?

Answer 10

A nebula

Question 11

What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together

Answer 11

Fusion reactions

Question 12

Gravity is greater closer to the star. Most of the dense material in the dust cloud is attracted strongly and ends up here. The left over ____ (dust/ gas) created rocky planets near the sun and the left over ____ (dust/ gas) created gas giants further away from the sun

Answer 12

Dust

Gas

Question 13

What is a light year?

Answer 13

The distance light travels in one year

Question 14

What is an astronomical unit (AU)?

Answer 14

The mean distance from the Earth to the Sun

Question 15

What unit of measurement is used to measure distances between the sun and planets ?

Answer 15

The Astronomical Unit (AU)

Question 16

Alpha Centauri is 4.4 light years away from us. Can you work out this distance in metres?

Answer 16

4.4 ly × 9.46 × 10^15 m / ly

= 4.16 × 10^16 m

Question 17

What colour stars are the hottest? Blue or red?

Answer 17

Blue stars are the hottest stars

Red stars are the cooler stars

Question 18

Put these things into order from smallest to biggest:

Milky Way
Earth
Solar system 
Universe
Sun

Answer 18

1) Earth
2) Sun
3) Solar System
4) Milky Way
5) Universe

Question 19

What factor determines the type of lifecycle a star undergoes?

Answer 19

The size (and therefore mass) of the star

Question 20

What two stages do all stars of the same or greater size than the sun undergo?

Answer 20

1. Protostar phase

2. Main sequence phase

Question 21

What do stars like the sun become at the end of their life-cycle?

Answer 21

A black dwarf

Question 22

What two things can stars much bigger than our sun become at the end of their lifecycle?

Answer 22

1. Neutron star

2. Black hole

Question 23

What two phases do stars like the sun experience between being a main sequence star and a black dwarf

Answer 23

1. Red giant

2. White dwarf

Question 24

What two phases do stars of greater size than our sun go through between being a main sequence star and a neutron star/ black hole?

Answer 24

1. Red supergiant

2. Supernova

Question 25

What condition is required for fusion reactions to occur in a star?

Answer 25

Very high temperatures and pressures

Question 26

Where are elements heavier than iron produced?

Answer 26

In a supernova

Question 27

What type of nuclei fuse together to form heavier elements in a star?

Answer 27

Hydrogen nuclei fuse to form heavier elements

Question 28

How are elements distributed throughout the universe?

Answer 28

Through the explosion of a massive star (supernova)

Question 29

What allows planets and satellites to maintain circular orbits?

Answer 29

Gravity provides the gravitational force that acts as the object's centripetal force (a force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving) The presence of a centripetal force allows for the object to maintain its circular orbit

Question 30

What type of satellite can a planet's moon be described as?

Answer 30

A natural satellite

Question 31

What type of planet is Pluto classed as?

Answer 31

A dwarf planet

Question 32

What is the name given to the natural satellites that orbit planets?

Answer 32

Moons

Question 33

What term is given to the 4 outer planets of our solar system?

Answer 33

Gas giants

Question 34

What is the order of stages in the life cycle in a high mass star?

Answer 34

1) Protostar 2) Main sequence star 3) Red supergiant star 4) Supernova 5) Neutron star (If star not one of biggest) 6) Black hole ( If star is one of biggest)

Question 35

What is the order of stages in the life cycle in a low mass star?

Answer 35

1) Protostar 2) Main sequence star 3) Red giant star 4) White dwarf 5) Black dwarf

Question 36

What is a protostar?

Answer 36

A cloud of gas and dust collapses due to gravity to form a baby star known as a protostar

Question 37

What is a Main Sequence Star?

Answer 37

When the protostar is hot enough to fuse hydrogen into helium it becomes a main sequence star

Question 38

What is a red giant?

Answer 38

Once all the hydrogen has run out the star expands into a red giant where it can fuse heavier elements together up to iron

Question 39

What is a White Dwarf?

Answer 39

When the star can't fuse anything together it sheds its outer layers and collapses into a small dense white dwarf. Overtime this will cool down and get dimmer.

Question 40

What is a red super giant?

Answer 40

If the star is much bigger than the sun it will become a red super giant when it runs out of hydrogen

Question 41

What is a supernova?

Answer 41

A supernova is a huge explosion of the star which is where all the elements heavier than iron are formed

Question 42

What is a black hole?

Answer 42

If the star is one of the biggest in the universe once it has exploded in a supernova it will become a black hole. These have gravity so strong that nothing can escape them (not even light)

Question 43

What is a neutron star?

Answer 43

If the star is not one of the biggest stars, after it has exploded in a supernova it will become a neutron star which is very dense and filled with neutrons

Question 44

``` Where can you fine these elements? Hydrogen Helium Elements bigger than helium (up to Iron) Elements bigger than iron ```

Answer 44

Hydrogen - The Big Bang Helium - main sequence stars Elements bigger than helium (up to Iron) - red giant/ red super giant stars Elements bigger than iron - supernova

Question 45

What are the two forces acting on a star?

Answer 45

Gravity (inwards) | Gas and radiation pressure (outwards)

Question 46

In which stage of a stars life is the forces of gravity and gas and radiation pressure equal? Hence meaning the star is stable.

Answer 46

Main sequence star

Question 47

When the star runs out of hydrogen there is no more fusion. This means pressure ______ (increases/ decreases). Gravity is bigger than pressure so the star _____. This causes it to get hotter and more dense. This extra heat means fusion can kick start again and the star can start to fuse helium. This means pressure ______ (increases/decreases). Pressure is now bigger than gravity so the star expands and cools down. This continues throughout the star's life time as a red super giant. This causes layers to be created with lighter elements on the outside and heavy elements in the centre.

Answer 47

decreases shrinks increases

Question 48

What does the Hertzsprung-Russell Diagram show?

Answer 48

The luminosity of stars against there temperature