5.) Topic 5 Stars And Planets

Question 1

In which galaxy is our solar system

Answer 1

The Milky Way Galaxy

Question 2

How many planets make up our solar system?

Answer 2

8 (plus the dwarf planets)

Question 3

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

Answer 3

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

Gravity (Gravitational force of attraction)

Question 5

Name all the planets in our solar system in order

Answer 5

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune

Question 6

What type of planet is Pluto

Answer 6

Pluto is a dwarf planet

Question 7

What type of planets are Mercury, Venus, earth and mars?

Answer 7

Rocky planets

Question 8

What type of planets Jupiter, Saturn, Urnaus, Neptune and Pluto

Answer 8

Gas planets

Question 9

Where is the asteroid belt located?

Answer 9

In between Mars and Jupiter

Question 10

What are asteroids?

Answer 10

Asteroids are lumps of rock which are in orbit of the sun

Question 11

Give an example of a dwarf planet in the asteroid belt and what is its diameter?

Answer 11

Ceres - diameter of 587 miles

Question 12

What are comets?

Answer 12

Comets are lumps of ice and dust which are in highly elliptical orbit of the sun

Question 13

Give an example of a comet and what’s the orbital period of it

Answer 13

Halley’s comet - orbital period of about 75 years

Question 14

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

Answer 14

A nebula

Question 15

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

Answer 15

Fusion

Question 16

What factor determines the type of lifecycle a star undergoes?

Answer 16

The size (and therefore mass) of a star

Question 17

What is another word given to moons?

Answer 17

Natural satellites

Question 18

What is AU

What does 1 AU equal

Answer 18

The mean distance from the centre of the earth to the centre of the sun

1AU = 1.496 x 10 (power of 11) metres

Question 19

What is a light year

What does 1 light year equal

Answer 19

Light year is the distance light travels in a year

1 Light year = 9.46 x 10 (power of 15) metres

Question 20

What does SM stand for

Answer 20

Solar masses

Question 21

Which 2 planets have no moons

Answer 21

Mercury and venus

Question 22

How does a solar system form? [4]

Answer 22

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

Question 23

What do stars produce by nuclear fusion?

Answer 23

Energy

Question 24

What colour are hot, bright stars

Answer 24

Blue

Question 25

What colour are very small, colder or old dying stars?

Answer 25

Red

Question 26

What makes a star stable

Answer 26

When fusion energy and gravity are equal

Question 27

Describe the life cycle of a star for smaller stars like our sun

Answer 27

Stars begin their life cycle as a cloud of dust and gas called a nebula

Gravity causes the cloud of dust and gas to collapse

As the particles move faster, the temperature rises to millions of degrees celcius. This early stage is called a proto-star.

Eventually the pressure gets so great that the particles fuse together. This is nuclear fusion when hydrogen nuclei fuse together to form helium nuclei

In a main sequence star, at some stage the hydrogen in the star will start to run out.

At this point the outward force due to fusion energy is less than the inward force due to gravity. This causes the star to collapse inwards. The collapse cause its temperature to increase. Now helium nuclei fuse together to form heavier elements up to Iron.

This forms a red giant which expels its outer layers and stops using helium. This is a plenary nebula.

The star than shrinks and forms a white dwarf. After a while, the white dwarf becomes cooler and forms a black dwarf.

Question 28

Describe the life cycle of a star for bigger stars

Answer 28

Once bigger stars run out of hydrogen, they leave the main sequence stage and expand to form red super giants.

Helium nuclei fuse together to form heavier elements. At some point, the red super giants stops carrying out nuclear fusion and explodes. This is called a supernova.

The temp of a supernova is high enough to form elements heavier than iron. These elements are ejected across the universe. If the star mass was greater than 25, it forms a black hole. It has such a large gravity that not even light can escape. If it mass less than 25, it forms a neutron star

Question 29

Describe life cycle of star (summary)

Answer 29

Nebula - protostar - main sequence star (smaller like sun)- red giant - plenetary nebula - white dwarf - black dwarf

Nebula - protostar - main sequence star (bigger stars) - red super giant- supernova - either black hole or neutron star

Question 30

Which 2 phases do stars like our sun experience between being a main sequence star and a black dwarf

Answer 30

Red giant

White dwarf

Question 31

Which 2 phases do bigger stars experience between being a main sequence star and a neutron star/black hole

Answer 31

Red super giant

Supernova

Question 32

What condition is required or fusion reactions to occur in star

Answer 32

Very high temps and pressures

Question 33

Where are elements heavier than iron produced

Answer 33

Supernova

Question 34

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

Answer 34

Hydrogen nuclei fuse to form heavier elements

Question 35

What allows planets and satellites to maintain circular orbits? x2

Answer 35

Gravity

Presence of a centripetal force

Question 36

Give 2 examples of artificial satellites

Answer 36

TV satellites

Satellites used for satellite imaging

Question 37

What does a Hertzsprung - Russell diagram show?

Answer 37

The luminosity of stars against their temperature

Question 38

What are brown dwarfs

Answer 38

Failed stars that don’t have enough mass in order to get hot enough to achieve nuclear fusion

Question 39

What are red dwarfs

Answer 39

Low mass stars that do achieve nuclear fusion. They are not very bright and have very long life times. They are main sequence stars

Question 40

At the end of a main sequence stage of our sun, what happens? (7)

Answer 40

. Light elements fuse in the centre
. Centre is exhausted of light elements - nuclear reactions top, causing pressure to drop
. Star nucleus shrinks, making density and temp to go up, allowing heavier elements to fuse
. Meanwhile the lighter elements continue fusing in a shell around the nucleus
. Stars like our sun never reach sufficient temps to fuse elements heavier than oxygen
. The outer layers of the star are pushed off by the radiation pressure of the core - enriching the interstellar medium with heavier elements
. A very dense core remains known as a white dwarf

Question 41

How is a new star born (6)

Answer 41

Material from supernova mixes up with interstellar dust and gas. Shockwave from supernova and kickstart collapse of nebula. The effect then is the dust and gas in a nebula contracts over time. As nebula contracts, gravitational collapse converts gravitational potential energy into kinetic energy. Eventually temps of nebula reach high temps and density for fusion to start - star is born.

During formation rock tended to gather closer to the Sun and formed rocky planets whilst gaseous substances gathered together at distances further from sun to form gas planets