1. What’s in the Night Sky?

2. How are stars classified?
COLOR
TEMPERATURE
BRIGHTNESS
SIZE
COMPOSITION

3. COLOR AND TEMPERATURE
The color of a star helps determine its temperature
RED,ORANGE, & YELLOW stars have a COLD TEMPERATURE
BLUE, BLUE-WHITE, & WHITE stars have a WARM TEMPERATURE

4. BRIGHTNESS
The brightness of a star depends on its SIZE and TEMPERATURE.
Apparent Brightness – brightness as seen from Earth
Absolute Brightness – the brightness a star would have if it were at a standard distance from Earth.

5. CHEMICAL COMPOSITION
Stars are made up of mostly Hydrogen and other elements.
SPECTOGRAPHS are used to determine the elements found in stars.

6. MEASURING DISTANCE TO THE STARS
Light-Year: the distance that light travels in one year
Parallax: the apparent change in position of an object when you look at it from different places.

7. Stars – How are stars created?

8. MAIN SEQUENCE STARS
The 1st and longest phase of a star’s life cycle is called the MAIN SEQUENCE.
During this stage, the size of the star will change very little

9. RED GIANT & SUPER GIANTS
2nd Stage of a star
A large, reddish star late in its life cycle
It expands and cools once it uses all its hydrogen.
Loss of hydrogen causes the star to shrink
Red Giants can be 10 or more times bigger than the sun
Super Giants are 100 times bigger than the sun

10. White Dwarfs Final stage of a star
Eventually the outer parts expand and drift into space creating a PLANETARY NEBULA
The blue-white core of the star that is left is a WHITE DWARF
After billions of years, the white dwarf stops glowing and what is left is a BLACK DWARF

11. SUPERNOVAS: When stars get old
When a Super GiaNT star runs out of fuel it explodes suddenly. This is called a SUPERNOVA
SUPERNOVAS: When stars get old

12. NEUTRON STARS Formed after a supernova
Gravity collapses a star to the point at which The old stars particles form together to create a neutron star
NEUTRON STARS

13. BLACK HOLES
Occurs when the center of a star that has a very high mass collapses and causes the star to contract
The force of the contraction crushed the center of the star and leaves a black hole
It is so massive that light cannot escape