1. Stars and the Star life Cycle
How do stars live out their lives?
What is the difference between mass and size?
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2. What is a star?
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A Star is sphere of matter where nuclear fusion is occurring
Nuclear fusion is when the nuclei of two atoms are pressed together under such pressure that they combine into one nucleus
What is the difference between a star and a planet?
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3. What is electromagnetic radiation?
Electromagnetic radiation is energy that travels through space in waves
The light you see is just a part of the electromagnetic specrum
Objects in space give off all kinds of radiation
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What is electromagnetic radiation?

4. Electromagnetic spectrum
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The different labels refer to the different wavelengths of energy
Wavelength is the distance from the crest of one wave, to the crest of the next wave
Glue your copy of the electromagnetic spectrum into your journal now

5. Telescopes
Telescopes are instruments what collect and focus light and other forms of electromagnetic radiation
The Hubble telescope is constantly collecting images of space using all kinds of electromagnetic radiation
The pictures in this powerpoint are of several different types of electromagnetic radiation
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6. Lives of Stars A star is born in a nebula
They are born when this contracting cloud of gas and dust becomes so dense and hot that nuclear fusion occurs.
How long it lives depends on its mass
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Lives of Stars

7. Star Nursery
A nebula is a large could of gas and dust spread out in an immense volume
Remember all matter has mass, and all mass has gravity
The densest part of the nebula pulls the matter around it in
Once there is enough mass, nuclear fusion occurs
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8. Once nuclear fusion begins, the star is called a protostar
There is still matter in the form of gas and dust that will still add to the star’s mass
During nuclear fusion, enormous amounts of energy are released
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Early Stages

9. Lifetimes of Stars How long a star lives depends on it’s mass
The larger the mass of a star, the faster it suns out of fuel
The most massive stars are blue, like the hottest part of the flame in a fire
The coolest stars have the least mass and are red
Remember mass and size are not the same
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10. What happens when a star runs out of fuel?
After a star runs out of fuel, it becomes a white dwarf, a neutron star, or a black hole
Only the most massive stars become black holes
The Sun will grow to a red giant, engulf Mercury, Venus and Earth, then keep expanding its outer layer out into space
Only the core, a white dwarf will remain
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What happens when a star runs out of fuel?

11. Supernovas
When a massive star runs out of fuel, it will collapse to the core, and fuse heavier elements and expand back out
This will happen several times until the core of the star is fusing iron
Once iron is formed, a star cannot form any heavier elements
It will collapse and the in a final explosion, form all of the heavier elements we know today in what is called a supernova
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12. After a supernova There are two results of a supernova
Neutron stars – can also be pulsars
Black holes – we don’t know much
Black holes are not holes at all
Black holes are places where there is so much mass, and so much gravity in such a small space, that the gravity does not even let light (electromagnetic radiation) out
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