Starter: where are we?

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

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

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

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

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 http://heritage.stsci.edu/public/Oct22/sgr1/sgrtable.html.

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 http://heritage.stsci.edu/public/Oct22/sgr1/sgrtable.html.

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

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

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

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

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

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

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

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

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