1. Starter: where are we?

2. The sun is one of billions of stars in our galaxy, the Milky Way

3. Objectives Learn the difference between a comet and an asteroid
Describe how stars are formed
Explain how the size of a star impacts the life cycle of a star

4. Comets and asteroids
Comets: have a frozen core of dust and gas. As they approach the sun the gases evaporate to form a tail making them easy to see
Asteroids: are a band of rock debris found between the orbits of Mars and Jupiter

5. The end... Many small asteroids collide with Earth each year
Although the chances are small, it is predicted that an asteroid between 1-10km could hit the Earth within the next million years
This could create devastating tidal waves and so much dust could be released into the atmosphere that light is prevented from reaching the Earth

6. Twinkle, Twinkle, Little Star ...
Hubble Heritage image of Sagittarius Star field. Note that along the horizontal axis, the image is 13.3 light-years across.
Ask audience what they notice by looking at this image. Hopefully they will notice the different colors. You can then ask them what the different colors mean [different temperatures]
Image from

7. How I wonder what you are!
Stars are all at different stages of their life cycles.
They do not last forever.
Some of the stars we see no longer exist!
Hubble Heritage image of Sagittarius Star field. Note that along the horizontal axis, the image is 13.3 light-years across.
Ask audience what they notice by looking at this image. Hopefully they will notice the different colors. You can then ask them what the different colors mean [different temperatures]
Image from

8. Star formation
Clouds of dust and gas called nebula are pulled together by strong gravitational forces
This increases the temperature and nuclear reactions start taking place
Massive amounts of energy are released and forms a star
Eventually the hydrogen gas runs out and the star gets colder and expands
What happens next depends on the size of the star

9. Put these stages of star formation in the correct order
Massive amounts of energy are released and forms a star
What happens next depends on the size of the star
Eventually the hydrogen gas runs out and the star gets colder and expands
Clouds of dust and gas called nebula are pulled together by strong gravitational forces
This increases the temperature and nuclear reactions start taking place

10. Check the order
Clouds of dust and gas called nebula are pulled together by strong gravitational forces
This increases the temperature and nuclear reactions start taking place
Massive amounts of energy are released and forms a star
Eventually the hydrogen gas runs out and the star gets colder and expands
What happens next depends on the size of the star

11. What happens next? If the star is about the size as the sun
The star cools and becomes a red giant
It continues to cool and then collapses under its own gravity to become a white dwarf
Eventually it becomes a black giant

12. What happens next? If the star is about the size as the sun
Label the flow chart

13. What happens next? If the star is about the size as the sun
Check your labels
Star
Red giant
White dwarf
Black dwarf

14. What happens next? If the star is much bigger than the sun
The star cools and becomes a red supergiant
It shrinks rapidly and explodes releasing energy dust and gas into space called a supernova
This dust and gas (nebula) forms new stars and the remains of the supernova will either be a neutron star or a black hole

15. What happens next? If the star is much bigger than the sun
Label the flowchart

16. What happens next? If the star is much bigger than the sun
Check your labels
Neutron star
Supernova
Star
Red supergiant
Black hole