Topic 5: Stars and Planets

Question 1

What is the order of the solar system?

Answer 1

Mercury 
Venus
Earth 
Mars
Jupiter
Saturn
Uranus
Neptune

Question 2

Group the planets that are rocky planets, gas giants and ice giants

Answer 2

Rocky planets = Mercury, Venus, Earth, Mars
Gas giants = Jupiter, Saturn
Ice giants = Uranus, Neptune

Question 3

Between which planets does the asteroid belt lie?

Answer 3

Mars and Jupiter. (Rocky and Gas)

Question 4

What are asteroids?

Answer 4

Lumps of rock (that orbit the Sun)

Question 5

What are comets?

Answer 5

lumps of ice and dust (which travel through the solar system)

Question 6

What is an astronomical unit (AU)?

Answer 6

The mean distance from the Earth to the Sun.

1 AU = 1.5 x 10¹¹

Question 7

What is a light year (ly)?

Answer 7

The distance light travels in one year.

1 ly = 9.5 x 10¹⁵

Question 8

If a main sequence star has a mass below/the same as the Sun, what happens to it?

Answer 8

Becomes a red giant, then a white dwarf.

Question 9

If a main sequence star has a mass way above the Sun, what happens to it?

Answer 9

It becomes a super red giant, then a supernova, then either a neutron star or black hole (takes a certain weight to become a black hole).

Question 10

What is a Nebula?

Answer 10

Large clouds of dust and gas (mainly hydrogen).

Begins a stars life.

Question 11

What is a Protostar?

Answer 11

A contracting cloud of gas and dust with enough mass to form a star.
Gravity forces the dust and gas to become more concentrated.
Nuclear fusion begins and produces energy.
The core gets brighter and hotter until the protostar is formed.

Question 12

What is a main sequence star?

Answer 12

A star which is stable, with balanced forces keeping it the same size all the time.
Much brighter and hotter than protostar.

Question 13

What is a red giant?

Answer 13

A star in which the Hydrogen has run out and energy is released from the fusion of Helium and other heavier elements.
Due to the energy created, the star expands.
Low mass star.
High radiation, lower temp.

Question 14

What is a white dwarf?

Answer 14

The hot and dense core of the red giant.

When the red giant runs out of its fuel it loses its outer layers

Question 15

What is a red super giant?

Answer 15

A high mass star that’s much larger than a red giant.
It therefore has more fuel, fuses heavier elements and has a lot more energy.
High radiation, lower temp.

Question 16

What is a supernova?

Answer 16

When a SUPER red giant runs out of fuel, it will collapse in on itself and causes a huge explosion. This is called a supernova.

Question 17

Where did we get all our heavier elements from?

Answer 17

Supernovas.

Any elements heavier than iron are made from supernovas.

Question 18

What is a black dwarf?

Answer 18

When a white dwarf cools down it becomes a black dwarf.

Question 19

What is a neutron star?

Answer 19

The core of a super red giant which is so compressed through the force of its own gravity that its protons and electrons have been squashed together and have finished up as neutrons.

Question 20

What is a black hole?

Answer 20

A celestial object that has a gravitational field so strong that light can’t escape from it.
Created after collapse of super red giant.

Question 21

What does it mean when a star is stable (in terms of forces)?

Answer 21

The inward force of gravity equals the outwards force of pressure.

Question 22

What happens when a star runs out of hydrogen? (a main sequence star commencing helium fusion)

Answer 22

There is no more fusion, the pressure decreases.
Gravity is bigger than pressure so the star shrinks and becomes more hot and dense.
Fusion stars again due to the extra heat; the star starts to fuse helium.
The pressure increases.
Pressure is now bigger than gravity so the star expands and cools down.

Question 23

Why are there no green stars?

Answer 23

Hydrogen absorbs green light.

Question 24

When a star is very hot , what colour is it?

Answer 24

Blue.

Question 25

When a star is colder, what colour is it?

Answer 25

red.